ISSN 0853–8980

INDONESIAN FISHERIES RESEARCH JOURNAL Volume 18 Number 2 Desember 2012 Acreditation Number: 503/AU2/P2MI-LIPI/10/2012 (Period: October 2012-October 2015) Indonesian Fisheries Research Journal is the English version of fisheries research journal. The first edition was published in 1994 with once a year in 1994. Since 2005, this journal has been published twice a year on JUNE and DECEMBER. Head of Editor Board: Prof. Ir. Badrudin, M.Sc. Members of Editor Board: Prof. Dr. Ir. Subhat Nurhakim, M.S. Prof. Dr. Ir. Ngurah Nyoman Wiadnyana, DEA Prof. Dr. Ir. Hari Eko Irianto Dr. Purwito Martosubroto Dr. Ir. Dede Irving Hartoto, M.Sc. Refrees for this Number: Prof. Dr. Ir. Ari Purbayanto, M.Sc. Prof. Dr. Ir. Setyo Budi Susilo, M.Sc. Dr. Ir. Augy Syahailatua Dr. Sonny Koeshendrajana Dr. Sudarto Dr. Estu Nugroho Managing Editors: Eko Prianto, S.Pi., M.Si. Arief Gunawan, S.Kom. Graphic Design: Kharisma Citra Partadinata, S.Sn. Published by: Agency for Marine and Fisheries Research Manuscript send to the publisher: Indonesian Fisheries Research Journal Research Center for Fisheries Management and Conservation Jl. Pasir Putih I Ancol Timur Jakarta 14430 Indonesia Phone (021) 64711940; Fax.: (021) 6402640 Email: [email protected], [email protected] Indonesian Fisheries Research Journal is printed by Research Center for Fisheries Management and Conservation Budgeting F.Y. 2012.

ISSN 0853 - 5884 INDONESIAN FISHERIES RESEARCH JOURNAL Volume 18 Nomor 2 December 2012 CONTENS Halaman PREFACE ………………………………………………………………………………………................

i

CONTENTS ………………………………………………………………………………………………….

ii

Stomach Content of Three Tuna Species in the Eastern Indian Ocean By: Bram Setyadji, Andi Bahtiar, and Dian Novianto…………………………………………………………

57-62

Exploitation and CPUE Trend of the Small Pelagic Fisheries in the Sulawesi Sea, Indonesia By: Lilis Sadiyah, Purwanto, and Andhika Prima Prasetyo…………………………………………………

63-69

Is There any Relationship Between Fluctuating Asymmetry and Reproductive Investment in Giant Featherback (Chitala lopis, Notopteridae) By: Arif Wibowo…………………………………………………………………………………………………

71-77

Performance of A Fishery Harvesting Different Minimum Shrimp Sizes in the Arafura Sea By: Purwanto...............................................................................................................................

79-89

Stock Enhancement in Indonesian Lakes and Reservoirs Fisheries By: Endi Setiadi Kartamihardja………………………………………………………...........................

91-100

Size and Fishing Ground of Wahoo (Acanthocybium solandri Cuvier, 1832) from Catch Data of Tuna Longline Operated in Indian Ocean By: Agustinus Anung Widodo, Fayakun Satria, and Budi Nugraha ………………………………………

101-106

iii

PREFACE Indonesian Fisheries Research Journal Volume 18 Number 2 December 2012 is the second publication of English journal of the Research Center for Fisheries Management and Conservation in 2012. The journal is expected to be a source of newest science and technology for all scientists and researchers in Indonesia and other countries. The financial for publication is provided by the Research Center for Fisheries Management and Conservation budget in the fiscal year of 2012. This volume contain the Stomach Content of Three Tuna Species in The Eastern Indian Ocean, Exploitation and CPUE Trend of The Small Pelagic Fisheries in The Sulawesi Sea, Indonesia, Is There Any Relationship Between Fluctuating Asymmetry and Reproductive Investment in Giant Featherback (Chitala lopis, Notopteridae), Performance of A Fishery Harvesting Different Minimum Shrimp Sizes in The Arafura Sea, Stock Enhancement in Indonesian Lakes and Reservoirs Fisheries, Size and Fishing Ground of Wahoo (Acanthocybium solandri Cuvier, 1832) from Catch Data of Tuna Longline Operated in Indian Ocean. We hope that all the articles on this volume may contribute significantly to the development of fishery science and technology in Indonesia. We are grateful to the editorial board for their improvement and suggestion on reviews of the manuscripts.

Editor

i

Stomach Content of Three Tuna Species in The Eastern Indian Ocean (Setyadji, B. et al.)

STOMACH CONTENT OF THREE TUNA SPECIES IN THE EASTERN INDIAN OCEAN Bram Setyadji, Andi Bahtiar, and Dian Novianto Reseach Station for Tuna Fisheries Received June 20-2011; Received in revised form December 6-2012; Accepted December 7-2012 E-Mail : [email protected]

ABSTRACT Feeding habit of tuna in Indian Ocean has been described around Sri Lanka, Indian Waters, Andaman Sea, western Indian Ocean (Seychelles Islands), western equatorial Indian Ocean whereas the tunas feeding habit study in Eastern Indian Oceanis merely in existence. The purpose of this study is to investigate the stomach content of three tuna species (bigeye tuna, yellowfin tuna, and skipjack tuna), apex predator in the southern part of Eastern Indian Ocean. The study was conducted in March – April, 2010 on the basis of catches of commercial tuna longline vessel based in Port of Benoa. A total of 53 individual fishes were collected, consisting of bigeye tuna (Thunnusobesus), yellowfin tuna (Thunnus albacores), and skipjack tuna (Katsuwonuspelamis). Stomach specimens were collected and analyzed.Analysis was conducted on the basis of index of preponderance method. The diet of the three tuna species showed fishes as the main diet (56–82%), followed by cephalopods (squids) as the complementary diet (0–8%), and crustaceans (shrimps) as the additional diet (2–4%). Fish prey composed of 6 families i.e. Alepisauridae, Bramidae, Carangidae, Clupeidae, Engraulidae, and Scombridae. Keywords: Stomach content, bigeye tuna, yellowfin tuna, skipjack tuna, Eastern Indian Ocean.

INTRODUCTION Fish diets are frequently characterised by great diversity of prey species, which can be related to opportunistic predation (i.e. non-selective) (Menard et al., 2006). Information related to food and feeding habit is important in understanding the life history of the species concerned, including growth, migration, and potentially useful for fisheries management (Effendie, 2002). The predator-prey interactions play an important part in the structure and the dynamics of multispecies communities (Notmoorn et al., 2008). Considering the fast increase of tuna catches and related species in the Indian Ocean, especially in the southern Indian Ocean, it becomes necessary to assess the impact of such kind of fisheries in the pelagic ecosystems. Research activitiesof such kind leading to a better knowledge of thropic ecology of apex predators is important nowadays in the context of ecosystem in fisheries management. Stomach content analyses are commonly used to study both fish feeding behavior and thropic conditions (Bertrand, 2002). However, the interpretation of such data depends on fish foraging behavior for a given environment and how representative the stomach contents are to the prey

_________________ Corresponding author: Research Station for Tuna Fihseries Benoa, Jl. Raya Pelabuhan Benoa, Denpasar Selatan, Bali.

distribution. The feeding habit of tuna in Indian Ocean has been described around Sri Lanka (Maldeniya, 1996; Dissanayake et al., 2008), Indian Waters (John, 1998; Nootmorn et al., 2008, Sivadas & Anasukoya, 1999; Rohit et al., 2010), Andaman Sea (Panjarat, 2006), Western Indian Ocean (Seychelles Islands) (Potier et al., 2004), Western Equatorial Indian Ocean (Potier et al., 2007) whereas hardly any study has been conducted in Eastern Indian Ocean. The purpose of this study is to analyse the stomach content of three tuna species (bigeye tuna, yellowfin tuna, and skipjack tuna) collected from fishing vessels operating in Eastern Indian Ocean. MATERIALS AND METHODS The study was done during March – April, 2010 on boardtwo commercial tuna longline vesselsbased in Port of Benoa. A total of 272 large pelagic fishes caught,53 of themwere sampled for observation, consisting of 32 bigeye tuna (Thunnusobesus) with size of 50 – 165 cm (FLT/Fork Length Tape), 10yellowfin tuna (Thunnus albacores) of 43 – 165 cm (FLT), and 11 skipjack tuna (Katsuwonuspelamis) of 30 – 96 cm (FLT). Samples were taken during fishing operation in Eastern Indian Oceanas shown in Fig. 1.

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Ind.Fish.Res.J. Vol.18 No. 2 Desember 2012 : 57-62 -8

Java Bali -10

East Timor INDIAN OCEAN

-12

-14

-16

Australia -18 109

111

113

115

117

119

121

123

125

Figure 1. Station distribution of samples collection (+ :bigeye tuna; “ : yellowfin tuna; : skipjack tuna) in Eastern Indian Ocean Stomach Analysis Procedures Where: Stomach analysis were conducted following this procedure: 1) the entire stomach was removed from the freshly caught fish when hauled on board; 2) size of the predator (fork length) and sex were recorded for each fish; 3) then a three-step activities were conducted: (a) total weight of the stomach contents was measured; (b) the stomach content was sorted by large categories (fish, mollusks, crustaceans); and (c) the weight of each category was recorded and; 4) classification was made to the lowest possible taxon using keys and descriptions of Nakabo (2002), FAO (1998) and Gloerfelt-Tarp and Kailola (1984).

FO : Frequency of Occurrence (%) A : Degree of occurrence to one particular type of diet in organism B : Total number of organism with non-empty stomach The calculation of IP was modified by replacing vior percentage of coverage of particular type of diet with percentage of weight, so the result expected to be more accurate. Based on index of preponderance the result can be classified into three categories (Nikolsky, 1963):

Data Analysis Index of Preponderance was used in order to analyze the main diet of an organism, developed by Natarjan & Jingran, (1962) after Mardlijah, (2008) with equation:

IP > 40% : Categorised as main diet. 4% > IP > 40% : Categorised as complementary diet. IP < 4% : Categorised as additional diet. RESULTS

IP =

(vi x oi) Σ (vi x oi)

x 100% .............................(1

Where: IP : Index of preponderance for specific type of diet vi : Percentage of weight of one particular type of diet (%) oi : Frequency of Occurrence (FO) (%) The value of oior FO was obtained throughthe following equation (Mardlijah, 2008): FO =

58

A B

x 100% ................................(2

Bigeye Tuna (Thunnus obesus) Of the total number of stomachs examined, 6 (11.5%) were empty. Out of 26 remaining stomachs (88.46%), 31.10% prey were digested and the rest (68.9%)as shown in Table 1. On a mass basis, undigested prey were recorded consisting of mackerel scad (family Carangidae) (29.0%), lancetfish (family Alepisauridae) (10.0%), sardines (family Clupeidae) (9.9%), sickle pomfret(family Bramidae) (3.3%), anchovy (family Engraulidae) (1.5%), unidentified fishes (2.6%), followed by squids (8.7%) and shrimps

Stomach Content of Three Tuna Species in The Eastern Indian Ocean (Setyadji, B. et al.)

(3.9%)(Fig. 2). Based on group of prey, fishes were likely favorable for main diet (48.31%), while

cephalopods as the complementary diet (4.18%) and crustacean as the additional diet (2.57%).

Table 1. Number of bigeye, yellowfin, and skipjack stomachs sample with percentage of empty and nonempty stomachs.

Species

Number of sample

Length (FLT)

Empty stomach

Non-empty stomach

n

%

n

%

Bigeye tuna

52

50 - 165

6

11.5

46

88.5

Yellowfin tuna

16

43 - 165

-

-

16

100.0

Skipjack tuna

9

30 - 96

-

-

9

100.0

shrimps 3.9% others

squids 8.7%

lancet fish

31.1%

10.0%

sickle pomfret

3.3%

unidentified fish 2.6% 1.5%

anchovy

mackerel scad

9.9% sardines

29.0%

Figure 2. Diet composition of bigeye tuna (Thunnusobesus). Yellowfin tuna (Thunnusalbacares)

Skipjack Tuna (Katsuwonuspelamis)

Disregarding the digested prey (15.5%), the diet proportion of yellowfin tunas showed a domination ofmackerel scad (53.9%), followed by lancetfish (7.9%), sardines (7.5%), mackerel (3.8%), anchovy (1.0%), sickle pomfret (0.2%), and finally followed by shrimps (2.1%) and squids (8.1%). (Fig. 3).Fishes placed as main diet for yellowfin tuna (67.7%),while cephalopods (1.5%) and crustacean (0.3%) as additional diet.

Only 9 skipjack tunas were observed. Less varied composition which probably due to small number of samples. Unidentified fishes (39.74%) dominated the diet composition, followed by mackerel scad (27.95%), sardines (7.42%), lancetfish (6.99%), and shrimps (3.93%), while the rest was filled by group of digested prey(Fig. 4). Fishes were likely as main diet (71.17%) and crustacean as additional diet (0.97%).

shrimps 2,08% 15,54%

others 3,80%

mackerel 1,04%

anchovy

13,97%

8,09%

others

squids

shrimps 3,93%

6,99%

lancet fish

7,86%

lancet fish mackerel scad

0,18%

27,95%

sickle pomfret

7,50%

sardines

unidentified fishes 39,74%

sardines 53,91%

7,42%

mackerel scad

Figure 3. Diet composition of yellowfin tuna (Thunnusalbacares).

Figure 4. Diet composition of skipjack tuna (Katsuwonuspelamis).

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DISCUSSION Disregarding the proportion of digested food, the diet proportion of the three tuna species were dominated by group of fishes category as the main diet (56–82%), cephalopods (squids) as the complementary diet (0–8%), and crustaceans (shrimps) as the additional diet (2–4%).Similar result reported by Allain (2005a) in Western and Central Pacific for albacore, bluefin, yellowfin and skipjack tuna where the important prey groups found in the stomachs (measured by weight) were fish (64–88%), mollusks (6–25%) and crustaceans (0.2–9%). While in the Bay of Bengal (Notmoorn et al., 2008) group of cephalopods were dominant in the diet composition for frigate tuna, skipjack tuna, bigeye, yellowfin and swordfish (60.7%), followed by group of fishes (38.8%). Observing stomach content on structure-associated aggregation conducted by Grubbs et al.(2001) found that bigeye tuna preyed on vertically migrating fishes rather than crustaceans on FAD-associated environment, while on seamount-associated environment, crustacean were likely became the main diet rather than teleost fishes. Basically tunas are opportunistic predators (Menard et al., 2006) feeding on a great variety of suitably sized forage fishes,crustaceans and squids (Collete & Nauen, 1983; Rohit et al., 2010, Vaske & Castello, 1998; Blunt, 1960; Nakamura, 1965).In the western tropical Indian Ocean, crustaceans were almost the exclusive food source of surface-swimming bigeye tuna,in the meantime bigeyetuna fed predominantly on cephalopods and mesopelagic fish, for which this predator appeared to be the most active chaser (Potier, 2004). Among three tuna species in this study, the yellowfin tuna showed to have the most diverse prey (Fig 2,3, & 4 for comparison). Percentage occurrence of major prey items from the previous research in Indian Ocean presented: a) Arabian Sea (Southern) – The prey items identified in 42 specimens in the order of preference are teleost fish (42.9%), squids (88.8%), crab (14.3%) and cuttle fish (4%); b) Bay of Bengal - The dominant prey items identified in 58 specimens are squids (39%), teleost fish (26.8%), crab (22%), shrimps (12.2%); c) Andaman and Nicobar waters – The important food items in 368 specimensidentified are squids 45.1%), teleost fish (33.5%), crabs (17.8%), Octopus (2.1%), Cuttle fish (1.2%) and Stomatopods (0.3%) and; d) Arabian Sea (Northern) - The gut content studies of 850 specimens from Arabian Sea (Northern), method indicates preponderence of squids (52.8%) and fin-fishes (40.7%). The other components observed were Cuttle fish (3.1%), Crabs (2.4%) and

60

Octopus (1%) 1 .W ith few exceptions, previous stomach content studies concluded that yellowfin tuna are opportunistic predators (Collete & Nauen, 1983; Menard et al., 2006) that feed on a tremendously diverse forage base, although the majority of the diet often comprises only a few families of epipelagic teleosts and crustaceans (Graham et al., 2006). Crustaceans also became the main diet for yellowfin tuna, which is higher than fishes or cephalopods according to percentage index of relative importantance for each food (IRI) as reported by Dissanayake et al. (2008) but by weight, fish prey was the most important prey with mackerel and lancetfish were likely became its main, ignoring sardines as bait. The diversity in food consumption in different sectors is indicative of the non-selective feeding nature of the species whereas the difference in the percentage composition of food items could be inferred as the availability of particular prey species rather than selection of preferred food items (Somvanshi, 2002). Skipjack tuna landed in Bitung, North Sulawesi had Mackerel scad (57%) as the main prey item, followed by sardines and mackerel (Mardlijah, 2008). In Lakshadweep, Pakistan, the percentage composition by volume of the stomach contents excluding live baits show that fishes formed 70%, crustaceans 11 % and cephalopod 19% with Decapterussp as one of the main prey (Sivadas & Anasukoya, 1999). While in Canary Islands Chub mackerel was the main prey, either as live bait or natural food (Ramos et al., 1995) because of the abundance of this species in the area. Similar result appeared in this study, with lancetfish, anchovy, and sickle pomfret also found. The presence of lancetfish in all three tuna species’ stomachs wasinteresting because itbecame bycatch in almost every longline fisheries in Indonesia (Nugraha & Wagiyo, 2006; Barata & Prisantoso, 2009; Prisantoso et al., 2010; Nugraha & Triharyuni, 2009; Nugraha & Nurdin, 2006). This happened because lancetfish plays an important role on pelagic food chain i.e. as predator on micronekton organisms(Romanov et al., 2008) alongside tunas (Bertrand et al., 2001)and as prey for billfshes and tunas (Potier et al., 2007). The multiplicity of prey found in this or previous studies indicate that perhaps skipjack or tunas in general are non-selective feeders and that stomach contents are probably determined by prey availability (Ramos et al., 1995). Diet studies provide information on basic biology and behaviour of the fish but they are also an important part of the parameterization of ecosystem models (Allain, 2005b); and information such as prey diversity,

Stomach Content of Three Tuna Species in The Eastern Indian Ocean (Setyadji, B. et al.)

size of the prey, composition of diet can be used as ecosystem indicators in conjunction with other indicators to detect changes in the ecosystem (Kirby et al., 2005).

Blunt, C. E. 1960. Observations on the food habits of longline caught bigeye and yellowfin tuna from the tropical eastern Pacific. California Fish and Game 1960. 46. p. 69-80.

CONCLUSION

Collette, B. B. & C. E. Nauen. FAO species 1983, catalogue. Vol. 2.Scombrids of the world. An annotated and illustrated c a t a l o g u e o f tunas, mackerels, bonitos and related species known to date. FAO Fish.Synop. 125 (2): 137 p.

The diet proportion of three tuna species were dominated by group of fishes as the main diet (56– 82%), followed by cephalopods (squids) as the complementary diet (0–8%), and crustaceans (shrimps) as the additional diet (2–4%). Fish prey composed of 6 families i.e. Alepisauridae, Bramidae, Carangidae, Clupeidae, Engraulidae, and Scombridae. Tunas in general are non-selective feeders and that stomach contents indicate by prey availability.

Dissanayake, D.C.T., Samaraweera, E.K.V. & C. Amarasiri. 2008. Fishery and feeding habits of yellowfin tuna (Thunnusalbacares) targeted by coastal tuna longlining in the north western and north eastern coasts of Sri Lanka. Sri Lanka J. Aquat. sci. 13. p. 1-21.

ACKNOWLEDGEMENTS This paper is part of authors’ contribution in research on study of genetic diversity and reproductive biology of large pelagic (bigeye, Thunnusobesus, scombrids family) in the Indian Ocean conducted during 2010 under Research Institute for Marine Fisheries. Authors would also like to thank to all of scientific observers for their contribution in collecting onboard data throughout the years.

REFERENCES Allain, V. 2005a.Diet of four tuna species of the Western and Central Pacific Ocean.SPC Fisheries Newsletter #114 – July/September 2005. 20 p. Allain V. 2005b. Ecopath model of the pelagic ecosystem of the WCPO.WCPFC-SC1, EBWP10.Noumea, New Caledonia, 9–18 August 2005. p. 30-33.

Effendie, M. I. 2002. Biologi perikanan.Yayasan Pustaka Nusatama. Yogyakarta.157 p. Graham, B.S., Grubbs, D., Holland, K. & B.N. Popp. 2006. A rapid ontogenic shift in the diet of juvenile yellowfintuna from Hawaii. Mar Biol 150. p. 647658. Grubbs, R.D., Holland, K.N. & D.G. Itano. 2001. Food habits and trophic dynamics of structureassociated aggregations of yellowfin and bigeye tuna (Thunnusalbacares and Thunnusobesus) in the Hawaiian Islands: Projectdescription, rationale and preliminary results. Yellowfin Research Group – SCTB 14. Noumea, New Caledonia, 9 – 16th August 2001. 5 p. John, M.E. 1998. A synoptic review of the biological studies on yellowfin tuna (Thunnusalbacares) in the Indian Seas. 7thExpert Consultation on Indian Ocean Tunas, Victoria, Seychelles, 9-14 November, 1998. p. 211-215.

Barata, A & B.I. Prisantoso. 2009. Beberapa jenis ikan bawal (Angel fish, Bramidae) yang tertangkap dengan rawai tuna (tuna long line) di Samudera Hindia dan aspek penangkapannya. BAWAL: 2 (5): 223-227.

Kirby, D., Allain, V & B. Molony. 2005. Potential ecosystem indicators for the WCPO. WCPFCSC1, EB-WP5.Noumea, New Caledonia, 9–18 August 2005.10 p.

Bertrand, A., Josse, E., Bach, P & F. Gerlotto. 2001. Tuna catchability with a longline related to trophic and tuna habitat characteristics. CM 2001/ Q:03ICES Annual Science Conference Oslo, 2629 September, 2001. 11 p.

Mardlijah, S. 2008. Analisis isi lambung ikan cakalang (Katsuwonuspelamis) dan ikan madidihang (Thunnusalbacares) yang didaratkan di Bitung, Sulawesi Utara.J. Lit. Perikan. Ind. 14. p. 227 – 235.

Bertrand, A., Bard, F.-X.& E. Josse. 2002. Tuna food habits related to the micronekton distribution in French Polynesia. Marine Biology 140. p. 10231037.

Maldeniya, R. 1996. Food consumption of yellowfin tuna, Thunnusalbacares, in Sri Lankan waters.Environmental Biology of Fishes 47. p. 101 – 107.

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Ménard, F., Labrune, C., Shin, Y.J., Ah-Soy Asine, A.S. & F.X. Bard. 2006. Opportunistic predation in tuna: a size-based approach. Mar. Ecol. Proc. Ser. 323.p. 223-231. Nakamura, E. L. 1965. Food and feeding habits of skipjack tuna (Katsuwonuspelamis) from the Marquesas and Tuamotu Islands.Transactions of the American Fisheries Society.Vol. 94, Issue 3, p. 236 – 242. Nikolsky, G. V. 1963. The ecology of fishes.Academic Press. New York. xv+352 p. Nootmorn, P., Sumontha, M., Keereerut, P., Jayasinghe, R.P.P.K., Jagannath, N. & M. K. Sinha. 2008. Stomach content of the three large pelagic fishes in Bay of Bengal. IOTC-2008WPEB-11. p. 1-13. Nugraha, B & E. Nurdin. 2006. Penangkapan tuna dengan menggunakan kapal riset M.V. SEAFDEC di perairan Samudera Hindia. BAWAL: 1(3). p.95 – 105. Nugraha, B & K. Wagiyo. 2006. Hasil tangkapan sampingan (by-catch) tuna long line di perairan Laut Banda. BAWAL: 1 (2). p. 71 -75. Nugraha, B & S. Triharyuni. 2009. Pengaruh suhu dan kedalaman mata pancing rawai tuna (tuna long line) terhadap hasil tangkapan tuna di Samudera Hindia. J. Lit. Perikan.Ind. 15 (3).p. 239 – 247. Panjarat, S. 2006. Preliminary study on the stomach content of yellowfin tuna in the Andaman Sea.In Preliminary results on the large pelagic fisheries resources survey in the Andaman Sea.SEAFDEC TD/RES/99. p. 114-122. Potier, M., Marsac, F., Lucas, V., Sabatié, R., Hallier, J-P.& F. Ménard. 2004. Feeding Partitioning among Tuna Taken in Surface and Mid-water Layers: The Case of Yellowfin (Thunnusalbacares) and Bigeye (T. obesus) in the Western Tropical Indian Ocean. Western Indian Ocean J. Mar. Sci.3(1).p. 51–62.

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Potier, M., Marsac, F., Cherel, Y., Lucas, V., Sabati´e, R., Mauryb, O & F. M´enard. 2007. Forage fauna in the diet of three large pelagic fishes (lancetfish, swordfish and yellowfin tuna) in the western equatorial Indian Ocean. Fisheries Research 83. p. 60–72. Prisantoso, B.I., Widodo, A.A., Mahiswara. & L. Sadiyah. 2010. Beberapa jenis hasil tangkap sampingan (by-catch) kapal rawai tuna di Samudera Hindia yang berbasis di Cilacap. J. Lit. Perikan.Ind. 16 (3).2010.p. 185 – 194. Ramos, A.G., Lorenzo, J.M. & J.G. Pajuelo. 1995. Food habits of bait-caught skipjack tuna Katuwonuspelamis off the Canary Islands. SCI. MAR., 59(3-4).p. 365 – 369. Rohit, P., Rao, G. S. & K. Rammohan. 2010. Feeding strategies and diet composition of yellowfin tuna Thunnusalbacares (Bonnaterre, 1788) caught along Andhra Pradesh, east coast of India. Indian J. Fish., 57(4).p. 13-19. Romanov, E.V., Ménard,F., Zamorov, V.V & M. Potier. 2008. Variability in conspecific predation among longnoselancetfishAlepisaurusferox in the western Indian Ocean. Fisheries Science; 74. p. 62–68. Sivadas, M. & A. Anasukoya. 1999. Observations on the food and feeding habits of the skipjack tuna, Katsuwonuspelamis (Linnaeus) from Minicoy, Lakshadweep. The fourth Indian Fisheries Forum Proceedings, 24-28 November, 1996.Konchi p. 57. Somvanshi, V.S. 2002. Review of biological aspects of yellowfin tuna (Thunnusalbacares) from the Indian Ocean. IOTC Proceedings no. 5. p. 420426. VaskeJr, T & J. P. Castello. 1998. Stomach contents of yellowfin tuna, Thunnusalbacares, during winter and spring in Southern Brazil. Rev. Bras. Biol. [online]. 58 (4), p. 639-647.

Exploitation and CPUE Trend ..... Fisheries in The Sulawesi Sea, Indonesia (Sadiyah, L. et al.)

EXPLOITATION AND CPUE TREND OF THE SMALL PELAGIC FISHERIES IN THE SULAWESI SEA, INDONESIA Lilis Sadiyah, Purwanto, and Andhika Prima Prasetyo Research Center for Fisheries Management and Conservation Received February 10-2012; Received in revised form December 10-2012; Accepted December 11-2012 E-Mail: [email protected]

ABSTRACT One of the expected benefits of the Sulu-Celebes Sea Project during its implementation is to have increased fish stocks at demonstration sites, as indicated by the Catch per Unit of Effort (CPUE). Analysis of catch and effort data of the small pelagic fisheries by using the surplus yield model was done to obtain information on the likely trend of CPUE for the last ten years. By using the pajeko as the standardized fishing gear the trend of CPUE has been calculated. Between 2000-2005, the trend of production (catch), effort and CPUE followed the general pattern of the exploited fisheries that already fully exploited, where the increasing trend of effort was not followed by the increasing catch. On the other hand, the trend of CPUE is decreased. In the following years, the trend of both catch and CPUE do not follow the general pattern of the exploited fisheries. The trend of catch, effort and CPUE has likely been stable, indicating that the fishery in this period has been leveled-off. The status of exploitation of the small pelagic fish resources in the Indonesian Sulawesi Sea is demermined by the MSY level that has likely been surpassed during the period 2003-2004. Therefore with the increasing effort in the following year the trend of catch was relatively stable. It is likely that the small pelagic fish stock in the Indonesian Sulawesi Sea might be ‘fully exploited’. Keywords : Exploitation, CPUE, Small Pelagic Fisheries, Sulawesi Sea

INTRODUCTION Different with some terrestrial resources consisted of relatively sedentary species and visible, the fish resources are invisible as they occupy habitat in the form of water body. But the fish resources provide living animal that are always moving and migrating in the effort of adjustment to fulfill their metabolic requirement suitable to the dynamic of biophysical environment. Most of the fish resources available in the waters around the districts located in the northern part of East Kalimantan Province or western part the Sulawesi Sea carry out their movement and migration from one place to another following the oceanographic conditions. Because the fish resource provides living animal, therefore they are belong to that so called renewable resources. Although, these resources could sustainably exploit when exploitation or fishing activities carry out do not exceed their ability to recover. The classical method of monitoring changes in fish stock abundance has been the use of catch and effort statistics from the commercial fishery. This has two big advantages as it can be cheap, since the basic data may be collected for other purposes, and because it may be based on the operations of hundreds of vessels, and tens of thousands or more fishing operations, the sample variance can be very small (Ulltang, 1977).

The fish resources in the waters around the districts and City of Tarakan have been exploited for years. Unfortunately, data and information especially basic data of catch and effort as well as some biological aspects related to the life history and population dynamics needed for stock assessment purposes, are considered inappropriate. In line with the increasing demand on the fish commodities either local, domestic and export, most of effort in increasing fish production are likely required research support regarding fish stock and its methodologies for rational exploitation so that the catches obtained could be maintained optimally and sustainably. It is therefore for rational and sustainable exploitation some management measures would be needed, otherwise the resources might be overfished and in turn the fisheries could be collapsed. This paper attempts to assess the present status of the small pelagic fish resources exploitation in the waters of the Sulawesi Sea Fisheries Management Area in the framework of the Sulu-Celebes Sea Sustainable Fisheries Management Project of the United Nation Office for Project Services (UNOPS) Project No.: 72595. One of the expected benefits of the Sulu-Celebes Project during its implementation from 2010-2014 is to have “increased fish stocks at demonstration sites (5-10 percent increase)”, as indicated by the Catch per Unit of Effort (CPUE). Trend of CPUE presented in this paper will provide one of the baselines data.

_________________ Corresponding author: Research Center for Fisheries Management and Conservation Jakarta Jl. Pasir Putih I Ancol Timur, Jakarta Utara

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MATERIALS AND METHODS In relation with the availability of statistical catch and effort data, data analysis carried out cover serial data of 2000-2009. Analysis of catch and effort data was focused to the small pelagic fish resources and its fishing gears used. As it is known that the fish resources in the waters of the Indonesian Sulawesi Sea has been exploited using a number of difference fishing gear with difference catchability. For the application of the surplus yield model, based on the available data a standardization of fishing gears need to be carried out through the estimation of fishing power index (FPI). With this work, the calculated annual fishing effort unit is presented in the form of equivalent with the standardized fishing gear.

The estimated FPI were calculated based on the production per unit gear, a sort of data available in the book of provincial fisheries statistics. Fishing gear with highest catch per gear having the FPI = 1.000 and assumed as a standard gear or standard effort. The FPI of other fishing gear were obtained by comparing catch per gear of a certain gear with the catch per gear that having FPI = 1.000. The annual total fishing effort was obtained through the addition of the multiplication between the number of fishing unit in a certain year and the FPI of that gear. Based on the appropriate provincial statistical data, the calculated FPI of each fishing gear for the small pelagic fisheries are presented in Table 1. The standard fishing gear for the small pelagic fishery in this analysis was mini purse seine or locally called as pajeko.

Table 1. Fishing gears and the estimated Fishing Power Index (FPI) in the waters of Indonesian Sulawesi Sea. Fishing gear Pajeko (mini purse seine) Drift gill net Encircling net Beach seine

FPI 1.00 0.01 0.16 0.05

The estimated FPI was based on the assumption that the same fishing gear in the period of 2000-2009 having the same catchability, same size or constant catchability which is needed for the application of the model (Pitcher & Hart, 1982). The final data resulted from the analysis provide basic data for the application of the Surplus Production Model (Sparre & Venema, 1999) that lead to the identification the trend of catch, effort and catch perunit effort (CPUE) that provide indicators for sustainable development. One of the indicators for sustainable development of fish resources is the time series of stock abundance index as one of the index of abundance or catch per-unit of effort (CPUE). RESULTS Sulu-Celebes Sea, with its terrestrial, coastal and marine ecosystems, were located in the global center of tropical biodiversity, exemplified by more than 500 species of reef-building corals and 2500 species of marine fishes (Chou, 1997; Veron, 2000). Five species of sea turtles (Green, Hawksbill, Olive Ridley, Loggerhead & Leatherback) and at least 22 species of marine mammals occur (GIWA, 2003). The marine fishery contributes significantly to the economies of Indonesia. Indonesia fisheries statistics indicate that North Sulawesi and East Kalimantan provide some

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Fishing gear Raft lift net Fixed lift net Other lift net

FPI 0.31 0.13 0.02

11% of the total national marine fishery landings (1997) (Khan & Fauzi, 2001). The fishery, although multispecies, is comprised predominantly by pelagic and to a lesser extent reef species. In this study it is defined that the pelagic resources consist of large and small pelagic groups. The large pelagic species include tuna, skipjack, tuna like/ frigate mackerel and spanish mackerel, while the small pelagic include scads, chub mackerel, sardines, anchovies, trevallies and big-eye trevally. Unit Stock Identification From taxonomical aspect, the fish resources in the waters around Districts and City of Tarakan are diverse in species, so that for the management and optimal as well as sustainable exploitation will need a number of assessment activities in relation with life history and population dynamics of the fish resource in more detail. The ability to identify fish species and unit stock provides a first step in fish stock assessment and these will determine the following studies. If the first step is not accurate, the level of accuracy in the following steps will be diverted and will lead to under or over estimated results and these will further affect the identification of optimal level of exploitation and their management measures.

Exploitation and CPUE Trend ..... Fisheries in The Sulawesi Sea, Indonesia (Sadiyah, L. et al.)

Due to the large fishing area and high diversity of fisheries economic scales on one side, while information obtained from research results are still very limited, so that for the implementation of research activities it needs to consider the limits of unit stocks, such as geographical barrier and stock parameters such as rates of growth and mortality. Beside the stock parameters estimation that can only be carried out after a number of data and information been collected in a relatively longer time, from the distribution of fishing activities and the existing geographical barrier will lead to the identification of unit stock. In case otherwise, assumption should be made that data analyzed are originated from one unit stock. This assumption is likely valid as this is supported by the genetic analysis reported by Borsa, (2003). It is further stated that the data presented in his study failed to support Hardenberg’s, (1937) hypothesis of three stocks in the western part of the Indo-Malay archipelago. Rohfritsch & Borsa, (2005) reported that at the scale of the entire Indo-Malay archipelago, however, at least three distinct populations of D. russelli were identified by the present study: (i) Arafura Sea, (ii) Sulawesi Sea and Makassar Strait and (iii) the rest of the Indo-Malay archipelago. A broadscale genetic homogeneity from the South China Sea to the Sulawesi Sea via the Java Sea and Makassar Strait have been reported byArnaud et al. (1999), while Perrin & Borsa, (2001) stated that the distinction of two clades within D. russelli is compatible with Pleistocene events that isolated the Sulawesi sea region from other areas in the Indo-Malay archipelago. Status of Small Pelagic Fisheries The present-day important of the maximum sustainable yield (MSY) is not so much as an objective to be rigidly followed in reaching decisions, but as a very convenient concept for use in discussing general management problems. This convenience arises because MSY serves, at least three distinct functions – a description of the facts of life regarding fish stocks in relation to exploitation, a clearly definable objective of management, and a measure of the success with which a stock is being managed (Gulland, 1983). Fishing grounds of the small pelagic fish in the waters of the Indonesian Sulawesi Sea are relatively large. This is due to the fact that beside the pajeko fishing gear operation with their high mobility, it is known that the small pelagic fish resources available in the waters are diverse with their wide distribution. From the information obtained during the survey period it was informed that some pajeko fishers operate their

gear in relatively far away from the Tarakan Bay as they carry out fishing in the bordering waters area with Sabah, Malaysia. The recorded small pelagic fish and analyzed based on the available catch and effort data were scads, trevallies, hard-tail scad, flying fish, mullets, sardine, rainbow sardines, chub mackerel, barracuda and gar-fish. Trend of production, effort and CPUE for the small pelagic fish group recorded in the book of fisheries statistics are presented in the Table 2. From that table it is appeared that during 1999-2006, the highest production of about 30,500 tonnes was recorded in 2003 while the lowest production of around 17,000 tonnes was recorded in 2000. Different with the production, the highest annual efforts of 3,194 equivalent pajeko units (mini purse seine) occurred in 2005 and the lowest efforts of 574 units were recorded in 2000. The fluctuation of CPUE in that period were likely followed the pattern of catch, where the highest CPUE of approximately 32 tonnes/pajeko units/year was occurred in 2003, while the lowest CPUE of only 8.6 tonnes/pajeko unit/year occurred in 2005. Based on data in Table 2, the trends of production, effort and CPUE are presented in Figure 1. From the figure it is appeared that between 2000 – 2005 the trend of production (catch), effort and CPUE followed the general pattern of the exploited fisheries that already fully exploited. This is shown in the figure where the increasing trend of effort was not followed by the increasing catch. On the other hand, the CPUE decreased (Figure 1). In the following years, the trend of both catch and CPUE do not follow the general pattern of the exploited fisheries. The trends of catch, effort and CPUE have likely been stable, indicating that the fishery in this period has been level-off. What is the recent status of exploitation of the small pelagic fish resources in the Indonesian Sulawesi Sea, it is appeared that the MSY level has likely been surpassed during the period 2003-2004. Therefore, with the increasing effort in the following year the trend of catch is likely relatively stable. It seems that the distribution of annual production points since 20052008 has already in the right hand side of the yield curve. It is likely that the present status of exploitation of the small pelagic fish is already in the state of ‘fully exploited’.

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Table 2. Production (catch), effort and catch per unit of effort (CPUE) of the small pelagic fisheries in the waters of the Indonesian Sulawesi Sea Fisheries Management Area. Year 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 *

Catch (tonnes) 17,166 25,696 22,055 30,534 24,002 27,325 26,179 26217 26,561 26,565

) Equivalent pajeko unit;

Effort *) 574 758 956 956 1,470 3,194 2,918 2,550 2,888 2,920

CPUE **) 29.9 33.9 23.1 31.9 16.3 8.6 9.0 10.3 9.2 9.1

**) Tonnes/pajeko unit/year

35.000 30.000 25.000 20.000 15.000 10.000 5.000 0 2000

2001

2002

Catch (tons)

2003

2004

2005

Effort*0.2

2006

2007

2008

2009

CPUE*0.002

Figure 1. Trend of Production (catch), effort (pajeko unit) and catch per-unit of effort (CPUE) of the small pelagic fisheries in the waters of the Indonesian Sulawesi Sea Fisheries Management Area. With regard to the transboundary aspects it is likely that the small pelagic fish stock (especially roundscads, Decapterus spp.) in the waters of Indonesian Sulawesi Sea forming one unit stock. As it is known that the roundscads, the most abundance and economically important small pelagic fish provide a relatively higher migratory species compare with the demersal fish. This phenomenon indicates that their exploitation forming a shared stock and consequently this resource has to be collaboratively managed. Information that has to be available will include their spawning ground, migratory pathway and some other population parameters. Trend of Catch Composition of the Small Pelagic Fisheries The occurring changes in species composition of fish caught in a certain waters reflecting a picture of

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the arising interactions that happening in a dynamic community as a result of the existence of fish population and a very dynamic nature of marine environment. These interactions can occur in form of predator-prey relationship or food competition. From the result of the small pelagic resources data analysis in the waters of the Indonesian Sulawesi Sea it was found that the annual catch of the species group shows a slightly different trend. With the assumption that these production (catch) data were proportional with the abundance of the fish resource in the sea, the occurring catch fluctuation is likely a response from the small pelagic fish community on the disturbing factors from outside. The main disturbing outside factors in the context of the exploited fisheries are fishing activities.

Exploitation and CPUE Trend ..... Fisheries in The Sulawesi Sea, Indonesia (Sadiyah, L. et al.)

20.000

Catch (tonnes)

16.000 12.000 8.000 4.000 0 2000 Scads

2001

2002 Trevallies

2003

2004

2005

Anchovies

2006

2007

Mackerel

2008

2009

Sardines

Figure 2. Trend of catch composition of the five species group of the small pelagic in the waters of the Indonesian Sulawesi Sea. The five species groups of the most economically important fish include scads and trevallies (Carangidae), anchovies (Engraulidae), chub mackerel (Scombridae), and sardines (Clupeidae). Other three dominant species groups with a little lower level of abundance include, flying fish (Exocoetidae), mullets (Mugillidae) and gar-fish (Hemirhampidae). The eight groups of the small pelagic fish are likely forming some species interaction among them, especially in the form of food competition. As be already acknowledged that feeding behaviour of most small pelagic species is plankton feeder. The most vulnerable species from the five groups of the small pelagic fish are likely the sardines group (Sardinella spp.), the mackerels and the trevallies. This was indicated by the relatively low level of the trend of annual production. Between 20002004 the trend of annual production was fluctuated, while in the following year was relatively stable (Figure 2). From the figure it is implied that the small pelagic fish production is dominated by scads, that reflecting the highest level of abundance of the species groups.

units/year was occurred in 2003 of where total catch and effort was 30,500 tonnes and 956 equivalent pajeko units, respectively. Between 2000 – 2005, the trend followed the general pattern of the exploited fisheries that already fully exploited, where the increasing trend of effort was not followed by the increasing catch. On the other hand, the trends of catch, effort and CPUE have likely been stable, indicating that the fishery in this period has been level-off.

DISCUSSION

With regard to the transboundary aspects it is likely that the small pelagic fish stock (especially roundscads, Decapterus spp.) in the waters of Indonesian Sulawesi Sea forming one unit stock. As it is known that the roundscads, shared stock, the most abundance and economically important small pelagic fish. Consequently, this resource has to be collaboratively managed.

Pajeko is the dominant fishing gears used in western part of Sulawesi, away from the Tarakan Bay as they carry out fishing in the bordering waters area with Sabah, Malaysia. There are five species groups of the most economically important fish include scads and trevallies (Carangidae), anchovies (Engraulidae), chub mackerel (Scombridae), and sardines (Clupeidae). From catch composition analysis was implied that the small pelagic fish production is dominated by scads, that reflecting the highest level of abundance of the species groups. CPUE trend between 2000 - 2009 showed that the highest CPUE of approximately 32 tonnes/pajeko

According to Borsa, (2003) that failed to support Hardenberg’s, (1937) hypothesis of three stocks of scad (Decapterus sp.) in the western part of the IndoMalay archipelago. There are three unit stocks of D. russelli rested in the Indo-Malay waters, namely: (i) Arafura Sea, (ii) Sulawesi Sea and Makassar Strait and (iii) the rest of the Indo-Malay archipelago. This is the important assumption for assessment of life history and population dynamics of the fish resource in Tarakan Waters.

Exploitation of pelagic and reef fisheries is also expected to increase, with a shift from local (subsistence) forms of fishing towards commercial, high capital investment forms. The expectation is will provide significant future deterioration, with likely severe socioeconomic hardship, particularly for the majority of the poor rural population (Abdullah et al.,

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2003; Licuanan & Gomez, 2000; Ingles, 2000). It is caused by the rapidly increasing coastal population, level of poverty, greater commercialization, decline in resources, lack of effective regulation and poor– nonexistent enforcement.

Arnaud, S., F. Bonhomme & P. Borsa. 1999. Mitochondrial DNA analysis of the genetic relationships among populations of scad mackerel (Decapterus macarellus, D. macrosoma, and D. russelli) in South-East Asia. Marine Biology. 135: 699-707.

CONCLUSION From the analysis of catch and effort data of the small pelagic fisheries by using the surplus yield it revealed that the trend of production (catch), effort and CPUE followed the general pattern of the exploited fisheries that already fully exploited, where the increasing trend of effort was not followed by the increasing catch. On the other hand, the CPUE decreased. In the following years the trends of catch, effort and CPUE have likely been stable, indicating that the fishery in this period has been level-off. It is likely that the present status of exploitation of the small pelagic fish might be already in the state of ‘fully exploited’. The most important aspect that needs to be considered is that the minimum level of CPUE of the gear (pajeko) that fishing activity is still economically profitable. Other aspect that also need to pay attention is that how to maintain optimum level of CPUE. This is due to the fact that if the effort tends to increase it can be expected that CPUE will decrease. The decrease of CPUE will certainly deduct the return of every operated fishing gear unit that finally leads to the bigger loss for every individual fisher. ACKNOWLEDGEMENTS The authors wish to thank the GEF (Sulu-Celebes Sea Sustainable Fisheries Management Project) has funded the research. We also would like to thank the Project Manager Office, the Sulu-Celebes Sea Sustainable Fisheries Management Project and Dr. Annadel S. Cabanban for her invaluable suggestions to this paper. REFERENCES Abdullah, A., Augustina, H., Alcala, A., Alino, P., Bachtiar, I., Bonifacio, R. Cabanban, A., Cheung, C., et al. 2003. Global International Waters Assessment Sulu-Celebes (Sulawesi) Sea Subregion 56 Scaling, Scoping, Causal Chain and Policy Options Analysis. Final Report to GIWA Secretariat, Kalmar University, Sweden. 183 p. Anonymous., 2001-2011. Capture fisheries statistics of Indonesia. Directorate General of Capture Fisheries. Ministry of Marine Affairs and Fisheries.

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Borsa, P., 2003. Genetic structure of round scad mackerel Decapterus macrosoma (Carangidae) in the Indo-Malay archipelago. Marine Biology: 142, 575-581. Chou, L.M. 1997. Southeast Asia as the global center of marine biodiversity. Tropical Coasts. 4: 4-8. GIWA 2003. http//:www.GIWA.net and http:// www.edc.uri.edu/lme/text Gulland, J.A, 1983. Fish stock assessment. A manual of basic methods. Vol. 1. John Wiley & Sons. 223 p. Ingles, J. 2000. Fisheries of the Calamianes Islands, Palawan Province, Philippines. In: A Rapid Marine Biodiversity Assessment of the Calamianes Islands, Palawan Province, Philippines. Werner, T.B. and Allen, G.R. RAP Bulletin of Biological Assessment 17. Washington DC. Conservation International. p. 45-64. Kahn, B. & Fauzi, A. 2001. Fisheries in the Sulu Sulawesi Seas - Indonesian Country Report. Assessment of the State of Biophysical, Socioeconomic, and Institutional Aspects of Coastal and Pelagic Fisheries in the Indonesian Part of the Sulu-Sulawesi Seas. WWF SuluSulawesi Marine Ecoregion Fisheries Project. 166 p. Licuanan, W.Y. & Gomez, E.D. 2000. Philippine Coral Reefs, and Associated Fisheries Status and Recommendations to Improve Their Management. Global Coral Reef Monitoring Network. Australia Institute of Marine Science. 44 p. Nurhakim, S., V.P.H.Nikijuluw, D.Nugroho & B.I.Prisantoso. 2007. Fisheries status in Fisheries Management Areas. Basic information for sustainable exploitation. Research Center for Capture Fisheries. MMAF. 47 p (In Indonesian). Perrin, C., Borsa, P. 2001. Mitochondrial DNA analysis of the geographic structure of Indian scad mackerel, Decapterus russelli (Carangidae) in the Indo-Malay archipelago. Journal of Fish Biology. 59, 1421-1426.

Exploitation and CPUE Trend ..... Fisheries in The Sulawesi Sea, Indonesia (Sadiyah, L. et al.)

Pitcher, T.J. & P.J.B. Hart, 1982. Fisheries Ecology. Croom Helm. London. 414 p. Rohfritsch, A. & P. Borsa. 2005. Genetic structure of Indian scad mackerel Decapterus russelli : Pleistocene vicariance and secondary contact in the Central Indo-West Pacific Seas. Heredity (2005) 95, 315–326.

Ulltang, O., 1977. Methods of measuring stock abundance other than by the use of commercial catch and effort data. FAO Fish. Tech. Pap. No. 176. FAO-UN. Rome. 23 p. Veron, J.E.N. 2000. Corals of the World. 3 Vols. Australian Institute of Marine Science. 1382 p.

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Is There Any Relationship Between … ……Featherback (Chitala lopis, Notopteridae) (Wibowo,A.)

IS THERE ANY RELATIONSHIP BETWEEN FLUCTUATING ASYMMETRY AND REPRODUCTIVE INVESTMENT IN GIANT FEATHERBACK (CHITALA LOPIS, NOTOPTERIDAE) Arif Wibowo Research Institute for Inland Fisheries, Mariana, Palembang, Indonesia. Received June 1-2012; Received in revised form December 17-2012; Accepted December 18-2012 E-Mail: [email protected]

ABSTRACT: Fluctuating asymmetry (FA) is often used as an indicator of perturbed development. As organisms placed under greater stress, less energy is available to buffer their development compared to unstressed individuals and increasing levels of asymmetry. Therefore, individual asymmetry scores within a population can be used as a measure of an organism’s ability to buffer its development and can be considered as an indirect measurement of individual fitness. In this study a test was conducted to know any correlation among FA and four fitness traits in giant featherback (Chitala lopis) inhabiting non acidified and acidified region along the Kampar River. Three bilateral meristic characters were counted on each side of the fish: number of gill rakers on the lower first branchial arch, eyes diameter, and number of pectoral-fin rays and four traits related to the fitness were measured: egg diameter, size of first maturity, gonad somatic index, and fecundity. Results show that FA (both number and magnitude) levels are differerent, giant featherback inhabiting more acidic station were slightly more asymmetric than those from less acidic one except to those inhabiting alkali station. However, the reproductive investment of giant featherback in the five sampling stations studied here gave no indication that the populations strongly affected by acidification. In this study it did not find any significant negative correlation between FA and any of the measured fitness traits. Therefore it can be concluded that FA is not a useful measure of fitness in this species. Keywords: Fluctuating asymmetry, chitala, reproductive investment

INTRODUCTION Fluctuating asymmetry (FA) is a population parameter that measures random deviation from perfect symmetry in bilaterally symmetric traits. Fluctuating asymmetry is important to population biologists because it reflects a population’s state of adaptation and co adaptation. FA is often used as a measure of developmental stability (Van Valen, 1962). In an ideal, stress-free environment, bilaterally symmetric characters (e.g. right vs. left arms in humans) would be produced that are morphometrically identical. In reality, no such system exists, as there will always be some elements of randomness in an organism’s development, resulting in asymmetry (Moller & Swaddle, 1997). Developmental stability therefore relates to the capacity of an organism’s developmental pathways to resist accidents and perturbations during the growth process (Moller & Swaddle, 1997). Normally, small perturbations during development are corrected by stability mechanisms, however when stressed, developmental mechanisms that buffer against the expression of asymmetric characters may break down, leading to the production of deviant phenotypes (Clarke, 1995). _________________ Corresponding author: Research Institute for Inland Fisheries Palembang. Jl. Mariana 308 Mariana-Palembang

In using FA, the underlying assumption is that development of the two sides of a bilaterally symmetric organism are controlled by an identical set of genes and therefore any non directional differences between the sides must be environmental in origin (Waddington, 1942). It has been argued that individuals with a high level of developmental stability have a selective advantage over individuals with lower developmental stability, and therefore developmental stability has been viewed as an integral component of individual fitness (Møller & Swaddle, 1997). The relationship between asymmetry and fitness has been extensively reviewed (Clarke, 1998; Møller, 1999), and several studies have reported a correlation between individual symmetry and fitness components such as fecundity and growth. Positive correlations between FA and environmental stresses have also been observed in various aquatic studies (Alados et al., 2001). In fish, individual and population levels of bilateral asymmetry have been shown to relate positively to a wide range of abiotic, biotic and genetic stresses. Abiotic factors such as acidification, toxic chemicals or heavy metals are common stressors which produce elevated levels of FA (Allenbach et al., 1999; Estes et al., 2006). The individual fitness of freshwater fish exposed to acidification (reduced pH and increased level of inorganic monomeric aluminium) is weaked

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because of reduced growth and decreased survival probability. When acidification is sufficiently strong, population effects are evident (Hesthagen et al. 1999). Asymmetry usually increases under environmental stresses because of the failure of the homeostatic regulatory mechanism (Bengtsson & Hindberg, 1985). However, at lower intensities it may be difficult to detect these population responses. FA may be an early indicator of such an acidification process, as well as of a number of other environmental disturbances (Leary & Allendorf, 1989; Sommer, 1996). In general, it suggests that giant featherback inhabiting acidified river are more asymmetric than those from non-acidified lakes. However, to use this variation in morphological asymmetry as a tool for conservation biological purposes it is necessary to document the association of morphological characters with individual fitness. If FA is correlated with fitness in giant featherback, it expect this correlation to be more pronounced and more easily detected in acidified river than in those in non-acidified river, owing to the larger expected variation in FA in giant featherback from acidified river. In this study, therefore, a test was conducted to know if FA is correlated with a number of fitness related traits (reproductive investment) in giant fetaherback from variety acidification status. MATERIALS AND METHODS Five sampling stations selected in Kampar River, Riau Province, which are vary in the level of acidification and there are no known local sources of pollution The water pH was checked in each sampling station using portable pH meter. These five sampling stations are: : Kutopanjang (GPS 00 019’5,39" N, 100044’3,79" E). Station II : Teso (GPS 00003’2,34" N, 101023’2,71" E). Station III : Langgam (GPS 00 0 15’4,69" N, 101042’4,55" E). Station I

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Station IV : Rantau Baru (GPS 00 0 17’1,06" N, 101048’1,22" E). Station V : Kuala Tolam (GPS 00 019’3,10" N, 102011’2,60" E). Giant featherbacks were sampled from late May 2009 until early November 2010 using some kind scope nets, fish traps and fishing line. In total, 84 individuals were captured (Table 1). Table 1. The number of individual for each sampling station No 1 2 3 4 5

Sampling Station Kutopanjang Reservoir Teso Langgam Rantau Baru Kuala Tolam Total samples

Number individual 16 14 12 25 17 84

The calculation of gonad somatic index was estimated as 100 (gonad mass/somatic mass). Gonad wet mass was measured with an accuracy of 0.01 g. For estimating fecundity, three subsamples (anterior, posterior and middle) of gonad were taken from each fish. Each subsample was weighed and then preserved in 70% ethanol. The eggs in each of the three subsamples were then counted per gram of wet gonad mass was used to estimate absolute fecundity (Effendie, 1979). A sample of 100 eggs was subjected to diameter measurement. Sperman Karber methods were used (King, 1985) to estimate the fish’s size of first maturity. Pectoral fins and first gill branchial arches were dissected from the fish, cleaned and dried, and examined using a dissecting microscope. Three characters were counted on each side of the fish: number of gill rakers on the lower first branchial arch, eyes diameter and number of pectoral-fin rays (Figure 1).

Is There Any Relationship Between … ……Featherback (Chitala lopis, Notopteridae) (Wibowo,A.)

Note : 1. Number of gill rakers on the lower first branchial arch 2. umber of pectoral-fin rays 3. Eye diameter

Figure 1. Observed fluctuation asymmetry characters Paired measurements were entered for each individual and transformed into signed asymmetry values according to the formula right–left. All the calculation were subject to estimate both the value of fluctuation asymmetry magnitude and number according to formulation by Leary et al. (1983):

FAm

(L R)

RESULTS The pH of sampling station in this study exhibit variation, Figure 2, showed a gradual decreasing of water pH from upstream to downstream in Kampar River.

.................................. 1)

8

N Z ...........................................2)

N Where : FAm = Fluctuation asymmetry magnitude Fan = Fluctuation asymmetry number L = Number of left’s organ R = Number of right’s organ Z = Number of asymmetry for certain characters. N = Sample number Multiple linear regressions were applied in STATISTICA 6.0 Package to test correlations between FA and fitness traits as described by øxnevald et al. (2002). The fitness parameters were fecundity, GSI, egg diameter, and gonad mass.

pH

FAn

7 6 5 4 Kutopanjang

Teso

Langgam

Rantau Baru Kuala Tolam

Observation

Figure 2. The value of water pH of sampling stations There were differences in total FA among giant featherback from five sampling stations both for number and magnitude (Figure 3).

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1.33

1.40 1.20 1.00

1.00

1.00

1.12

1.07

0.88

0.79 0.81

0.80

0.96

1.07

0.60

The giant featherback in this study also exhibit variation in fitness trait examined (Figure 4). Egg diameter and gonad somatic index characters found that the fish from Kuala Tolam showed the highest level in fecundity than those fish in Teso and Langgam. This population also has the smallest size of the first maturity.

0.40 0.20 0.00 Number

Magnitude KT

LG

RB

ST

WD

Gonad Somatic Index (%)

Figure 3. The value of overall Index of fluactuating asymmetry

1.4 Egg Diameter (mm)

There was a correlation between FA and the minimum size of fish maturity and there was no correlation among FA and gonad mass, egg diameter or fecundity (Table 2). However, when it performed 40 individual multiple regressions (5 sampling stations x 2 charcaters FA x 4 fitness parameters) using fitness trait as the dependent variable and FA estimate as independent variables, in non of the multiple regressions was find a significant FA effect (all P > 0.05).

1.2 1 0.8 0.6 0.4

0.20 0.15 0.10 0.05 0.00 Kutopanjang Teso

Langgam Rantau

0.2 Kutopanj ang

Teso

Langgam

Rantau Bar u

Baru

Kual a Tolam

Sampling Station

12000 11000 10000 9000 8000 7000 6000 5000 4000 3000 2000 1000

First M aturity (mm)

Fecundity

Sam pling Station

Kut opanjang

Teso

Langgam

Rant au Baru

Kuala Tolam

900 880 860 840 820 800 780 760 740 720 700 680 660 640 620 600

Male Female

Kutopanjang

Kuala Tolam

Teso

Langgam

Rantau Baru

Kuala Tolam

Sampling Station

Sampling Station

Figure 4. Reproductive investments of giant featherback Table 2. Correlation between FA and fitness trait

Number Magnitude Number (FA index) Magnitude (FA index) Gonad somatic index Egg diameter Fecundity Size of the first maturity

74

1.000 0.920 0.049 -0.082 0.399 -0.827

0.920 1.000 0.111 0.225 0.761 -0.585

Gonad Egg Size of the Fecundity somatic index diameter first maturity 0.049 -0.082 0.399 -0.827 0.111 0.225 0.761 -0.585 1.000 0.788 0.213 -0.237 0.788 1.000 0.769 0.072 0.213 0.769 1.000 0.003 -0.237 0.072 0.003 1.000

Is There Any Relationship Between … ……Featherback (Chitala lopis, Notopteridae) (Wibowo,A.)

DISCUSSION This work shows that FA (both number and magnitude) levels differ between giant featherback populations inhabiting vary acidified environment, the sampling stations were either non-acidified or affected differently by acidification. The result of the study was that giant featherbacks inhabiting more acidic sampling site were slightly more asymmetric than those from less acidified sampling, an exception made on those inhabiting alkali environment. However, studies on the reproductive investment of the fish in the five sampling station studied here give no indication that the populations are strongly affected by acidification. This study confirms øxnevald et al. (2002) opinion’s that there is no connection between FA and reproductive investment in animal organism. Since FA was higher in the more acidic sampling station than in the less acidic one, FA might function as an early-warning signal. However, to be a reliable estimator of population viability, FA needs to be correlated with some fitness trait such as reproductive investment, fecundity, or egg size, but it found no such correlation. It almost found the possibility such as relationship in acidified station, where the possibility is better, it was find a non significant negative relationship between FA and fitness-related traits. There are at least two possible explanations for this. The first is that there is a nonlinear relationship between FA and fitness-related traits, which is only evident at high asymmetry values. The second explanation is that there is, in fact, no relation between FA and the fitness related traits measured (øxnevald et al., 2002). In general, giant featherback living in more acidic station were more asymmetric than those living in less acidic station. A few other studies have reported on the relationship between FA and fitness in fish. Sasal & Pampoulie, (2000) studied FA and fecundity in the gobid species Pomatoschistus microps. They correlated pectoral-fin asymmetry in nesting males with the number of eggs in the nest and the density of eggs. They found no significant correlation between FA and male fitness. Downhower et al. (1990) measured otolith asymmetry and fecundity in the sculpin Cottus bairdi at eight localities in Montana and Ohio, USA. They found that otolith asymmetry was negatively correlated with egg number and egg mass. However, the power of this analysis is questionable, since no details of the statistical treatment are given. In this study, although there was a negative correlation between the size of first maturity and FA,

however the result it self was not significant. Thus it might be that the environmental stress experienced in the acidified station studied here is insufficient to produce strong asymmetry, and that the relationships between asymmetry and fitness traits are only evident at such higher stress levels. Further, it also seems that acidification stress has to be strong to induce strongly asymmetric morphology in fish (øxnevald et al., 2002). It is apparent from the literature that organismal developmental stability can be impaired through exposure to chemical pollutants and these stressors can result in an increase in fluctuating asymmetry. For example, some authors (Ames et al. (1979); Zakharov (1981); Jagoe and Haines (1985)) all found increased levels of fluctuating asymmetry in fish species inhabiting ponds with high concentrations of mercury and/or low pH. A number of studies do report only weak or no effects of relatively strong acidification on asymmetry (Wiener & Rago, 1987; Vøllestad & Hindar 1997, 2001). It may also be the case that asymmetry in general is not correlated with fitness traits (øxnevald et al. 2002). In a literature survey, Møller, (1999) presented the estimates of the magnitude and robustness of the relationship between asymmetry and three fitness components: growth, fecundity, and survival. However, the mean correlation coefficients were relatively small and accounted only for 12.3% of the variance in fecundity. The conclusion from Møller’s study is that asymmetry is generally negatively correlated with fitness components. However, earlier reviews and commentaries were contradictory (Clarke, 1995, 1998; Møller, 1997, 1999). What is evident, however, is that in order to use asymmetry as an indicator of the viability of a population or the fitness of an individual, the causal relationship between asymmetry and the fitness trait has to be documented. In this study on giant featherback it did not find a negative correlation between FA and any of the measured fitness traits. It therefore concluded that FA is not a useful measure of fitness in this species. These results do not imply that FA is an unreliable technique in assessing population stress, but speak to the difficulty in selecting traits that are not highly canalized, and are also under development when the stressor(s) affecting the population is being applied. Therefore, the usefulness of fluctuating asymmetry as a conservation tool is dependent upon the identification of such traits, and should be limited to cases where the agent causing the stress or reduction in population numbers has the opportunity of affecting a species’ physiology during development of the trait under study so it can be manifested in the organism’s morphology. However, under the right circumstances,

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fluctuating asymmetry monitoring techniques may prove to be very reliable.

Effendie, M.I. 1979. Fisheries Biology Methods. Yayasan Dewi Sri. Bogor. (in Bahasa Indonesia). 112 p.

CONCLUSION There are FA (both number and magnitude) levels differerence, giant featherback inhabiting more acidic sampling site were slightly more asymmetric than those from less acidified sampling. However, it did find any non significant negative relationship between FA and fitness-related traits. It is therefore concluded that FA is not a useful measure of fitness in this species.

Estes, E.C.J., C.R. Katholi & R.A. Angus. 2006. Elevated fluctuating asymmetry in eastern mosquitofish (Gambusia holbrooki) from a river receiving paper mill effluent. Environ. Toxicol. Chem. 25: 1026–1033. Hesthagen, T., I.H. Sevaldrud & H.M. Berger. 1999. Assessment of damage to fish populations in Norwegian lakes due to acidification. Ambio, 28: 112–117.

ACKNOWLEDGEMENTS Thanks to Subagja and Dwi Atminarso for their kind help during the field and laboratory work. The study was supported financially by a grant from the Research Institute for Inland Fisheries Fy 2009 and 2010 budgets.

Jagoe, C. H. & T. A. Haines 1985. Fluctuating asymmetry in fishes inhabiting acidified and unacidified lakes. Canadian Journal of Zoology. 63: 130-138.

REFERENCES

King, M. 1995. Fisheries Biology. Assesment and Management. Fishing News Books, Blackwell Science Ltd. 341 p.

Alados, C.L. T. Navarro, J. Escós, B. Cabezudo & J.M. 2001. Translational and fluctuating asymmetry as tools to detect stress in stress-adapted and nonadapted plants. Int. J. Plant Sci. 162: 607-616.

Leary, R.F., F.W. Allendorf & K.L. Knudsen. 1983. Developmental stability and enzyme heterozygosity in rainbow trout. Nature (Lond.). 301: 71–72.

Allenbach, D.M., K.B. Sullivan & M.J. Lydy. 1999. Higher fluctuating asymmetry as a measure of susceptibility to pesticides in fishes. Environ. Toxicol. Chem. 18: 899–905.

Leary, R.F., & F.W. Allendorf. 1989. Fluctuating asymmetry as an indicator of stress: implications for conservation biology. Trends Ecol. Evol. 4: 214–217.

Ames, L. J., J. D. Felley, & M. H. Smith. 1979. Amounts of asymmetry in centrarchid fish inhabiting heated and nonheated reservoirs. Transactions of the American Fisheries Society.108: 489-495. Bengtsson B.E & M. Hindberg. 1985. Fish deformities and pollution in some Swedish waters. Ambio. 14: 32-35. Clarke, G.M. 1995. Relationships between fluctuating asymmetry and fitness: how good is the evidence? Pac. Conserv. Biol. 2: 146–149. Clarke, G.M. 1998. Developmental stability and fitness: the evidence is not quite so clear. Am. Nat. 152: 762–766. Downhower, J.F., L.S. Blumer, P. Lejeune, P. Gaudin, A. Marconato & A. Bisazza. 1990. Otolith asymmetry in Cottus bairdi and C. gobio. Pol. Arch. Hydrobiol. 37: 209–220.

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Møller, A.P. 1997. Developmental stability and fitness: a review. Am. Nat. 149: 916–932. Møller, A.P. 1999. Asymmetry as a predictor of growth, fecundity and survival. Ecol. Lett. 1: 149–156. Møller, A.P., & Swaddle, J.P. 1997. Asymmetry, developmental stability, and evolution. Oxford University Press, Oxford. 291 p. Øxnevad, S.A., E. Heibo, & L.A. Vøllestad. 2002. Is there a relationship between fluctuating asymmetry and reproductive investment in perch (Perca fluviatilis)?. Can. J. Zool. 80: 120–125. Sasal, P & C. Pampoulie. 2000. Asymmetry, reproductive success and parasitism of Pomatoschistus microps in a French lagoon. J. Fish Biol. 57: 382–390. Sommer, C. 1996. Ecotoxicology and developmental stability as an in situ monitor of adaptation. Ambio. 25: 375–376.

Is There Any Relationship Between … ……Featherback (Chitala lopis, Notopteridae) (Wibowo,A.)

Van Valen, L. 1962. A study of fluctuating asymmetry. Evolution, 16: 125–142. Vøllestad, L.A., & K. Hindar. 1997. Developmental instability and environmental stress in Salmo salar (Atlantic salmon). Heredity. 78: 125–222. Vøllestad, L.A., & K. Hindar. 2001. Developmental stability in brown trout: are there any effects of heterozygosity or environmental stress? Biol. J. Linn. Soc. 74: 351–364.

Waddington, C.H. 1942. Canalization of development and the inheritance of acquired characters. Nature (Lond.). 150: 563–565. Wiener, J.G., & P.J. Rago. 1987. A test of fluctuating asymmetry in bluegills (Lepomis macrochirus Rafinesque) as a measure of pH-related stress. Environ. Pollut. 44: 27–36. Zakharov, V. M., E. Pankakoski, B. I. Sheftel, A. Peltonen & I. Hanski. 1991. Developmental stability and population dynamics in the common shrew, Sorex araneus. The American Naturalist. 138: 797810.

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Performance of A Fishery Harvesting Different Minimum Shrimp Sizesi in The Arafura Sea (Purwanto)

PERFORMANCE OF A FISHERY HARVESTING DIFFERENT MINIMUM SHRIMP SIZES IN THE ARAFURA SEA Purwanto Research Center for Fisheries Management and Conservation Received August 7-2012; Received in revised form December 19-2012; Accepted December 20-2012 E-mail : [email protected]

ABSTRACT Avoiding overfishing and ensuring the sustainability of the shrimp stock in the Arafura Sea are of prime importance for fishery management. Exploited shrimp stock consists of several cohorts, and grows considerably with age. When the shrimps are caught before the cohort has had the opportunity to achieve its optimum biomass level, the fishery will lose much of the potential benefit that could be achieved by catching them in the near future. Therefore, a bio-economic approach was developed, on the basis of the length-based Thompson & Bell model, to evaluate the impact of harvesting different size of shrimps on fishery performance. The result of analysis shows that the fishery achieved the optimal total profit when the shrimp size at first-capture and fishing mortality were 29 mm CL and 0.50, respectively. The total profit to the fishery would be sub-optimal when the shrimp size at-first-capture was smaller or larger than the optimal size. Further, it was more economical to harvest shrimps at the larger size and higher fishing mortality, and resulting in higher total profit, when natural mortality decreased. KEYWORDS: Bio-economic, Thompson & Bell model, shrimp fishery, optimum size at first capture.

INTRODUCTION Arafura Sea is one of the most productive fishing grounds for shrimp fishery in Indonesia. This fishing ground is highly productive (Bailey et al., 1987), as this area is shrimp habitat that is regularly enriched by nutrient rich upwelling and nutrient inputs from river flow, and supported by nursery sites in the coastal area. The Arafura Sea is one of the few areas within the Indonesian EEZ where nutrient rich upwelling occurs. In the Banda and Arafura Seas, upwelling develops under the influence of the southeast monsoon (Wyrtki, 1961). The upwelling increases nutrient (Wetsteyn et al., 1990), organic carbon (Cadee, 1988), which in turn increases phytoplankton biomass. Then, this increases oxygen production (Tijssen et al., 1990), and zooplakton abundance (Baars et al., 1990). Meanwhile, water mass flowing in the large rivers carries nutrient from the dense forest in the hinterland of Papua into the Arafura Sea during rainy season. Nutrient is also transported to the Arafura Sea from the dense mangrove area along the west coast of Papua (Sadhotomo et al., 2003). However, High primary productivity in the Arafura Sea during the southeast monsoon were not due to river runoff but by vertical mixing with the nutrient rich deeper water (Wetsteyn et al., 1990). The mangrove area also contributes to the productivity of the fishing ground in the Arafura Sea from its function as nursery site of shrimps. The association of post-larvae and juvenile of shrimps with mangroves are reported e.g. by

Robertson & Duke (1987), Vance et al. (1990, 1996, 2002), Primavera (1997, 1998), and Nagelkerken et al. (2008). Based on the estimates of potential yield of Indonesian marine fisheries (Indonesia’s Ministerial Decree of Marine Affairs and Fisheries no. 45 year 2011), the shrimp stock in the Arafura Sea can sustainably produce about 45% of the total potential yield of shrimps of Indonesia. The trawlable area for shrimp fishing in the Arafura Sea was about 74,000 km2, for water depths ranging from 10-50 m (Naamin, 1984; Sadhotomo et al., 2003). The commercial fishing operation targeting shrimps in the Arafura Sea was started in the early 1970s after the findings rich shrimp stocks and the introduction of the double rigged shrimp trawl in that fishing area during the late 1960s, prompted by strong international demand for shrimp (Bailey et al., 1987). Trawl became one of the main fishing gears in Indonesia as it was the most productive fishing gear for demersal fisheries. The fishing capacity of trawl fleet in the Arafura Sea was continuously developed. Fishing pressure to the shrimp stock further increased with the operation of fish trawlers in Arafura Sea since mid1980. The development of fishing fleet targeting shrimp stock has substantially reduced the abundance of demersal stocks in this area. Naamin, (1984), Badrudin et al. (2002) estimated optimal effort required to produce optimal yield from the utilisation of the shrimp

_________________ Corresponding author: Research Center for Fisheries Management and Conservation Jakarta Jl. Pasir Putih I Ancol Timur, Jakarta Utara

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stock in the Arafura Sea. Meanwhile, Widodo et al. (2001) evaluated the development of demersal fishery, including shrimp fishery, in the Arafura Sea and concluded that the stocks of demersal fishes and shrimps in this area were over-exploited. The overexploitation of shrimp stock in the Arafura Sea has threatened sustainability of these resources (Widodo et al., 2001).

The objective of this paper is to develop a bioeconomic analysis of shrimp fishery in the Arafura Sea facilitating the evaluation of impact of harvesting different size of shrimps on the performance of fishery. The model then is used to evaluate at-first-capturesize of shrimps and fishing mortality level that result in optimum profit. The evaluation is also undertaken at different natural mortality levels.

The area of shrimping in the Arafura Sea covered not only offshore but also inshore areas, which was nursery site of shrimps. Those fishing activities using net with mesh sizes that were not wide enough for small-size shrimps, including juveniles, to escape could result in growth overfishing. Growth overfishing in the shrimp fishery happens when shrimps caught before they have time to realise their growth potential, this occurs when fishing effort is higher and size of shrimp harvested is smaller than levels of effort and size of shrimps that produce maximum sustainable yield (MSY) or maximum yield-per-recruit in a fishery (Pauly, 1994; Caillouet et al., 2008). The non-targeted catches in the form of juveniles are disadvantageous, as this would reduce future yield and possible subsequent recruitment to the fishery. When the shrimps are caught before the cohort has had the opportunity to achieve its optimum biomass level, the fishery will lose much of the potential yield that could be achieved by catching them in the near future (Najmudeen & Sathiadhas, 2008). Results of the study in India conducted by Najmudeen & Sathiadhas, (2008) show that the current profit to the fishery from harvesting juvenile shrimps is smaller than forgone future profit from gaining larger size and higher price if the juveniles are not caught so having chance to grow before captured. However, Najmudeen & Sathiadhas, (2008) do not present the minimum size of a cohort resulting in optimum profit to fishery.

MATERIALS AND METHODS

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A bioeconomic approach was used in the analysis, covering bio-physical and economic aspects, of the Arafura shrimp fishery. The method in the bio-physical analysis, that was used to estimate the catch weight, catch rate, mean individual weight of the shrimps in the catch and the biomass for each level of annual fishing efforts, is based on a yield analysis introduced and used by Thompson & Bell, (1934). The lengthbased Thompson & Bell model (Sanders, 1995; Sparre & Venema, 1998) was used in this paper. A spreadsheet was used in the calculation. The step of calculation was very similar to the steps described by Sanders (1993, 1995). The difference is the use of a fixed fish price by Sanders (1993, 1995), while in this paper price varies with shrimp size. The equations used in the analyses that can be categorised as biophysical and economic components are presented in Table 1. The majority of the input parameters used in this paper are from Naamin, (1984) and Purwanto, (2008, 2011). These input parameters are presented in Table 2. Other input parameters that are not available consist of annual natural mortality coefficient, recruit number at zero age, and shrimp price at different length classes. Therefore, these parameters were estimated in this study.

Performance of A Fishery Harvesting Different Minimum Shrimp Sizesi in The Arafura Sea (Purwanto)

Table 1. Variables & parameters of the equations used in the analysis Variables & parameters

Symbols

Equation number

Equations

Bio-physical component: Start length (cm) at k End length (cm) at k Start age (year) at k End age (year) at k Mean individual weight (gm) at k

L1 L2 t1 t2 w

Fishing mortality coefficient at k Natural mortality coefficient at k End population no. (million) at k Mean population no. (million) at k Catch no. (million) at class k Natural death no. (million) at k Catch weight (t) at k Number of shrimps per kg at k Total catch no. (million) Total catch weight (t) Catch rate (kg/vessel) Mean individual weight (gm)

F M N2 N Cn D Cw n Cn' Cw' CR w'

L1 = Linf *{1 – e [–K(t1–t0)]} [–K(t –t )] L2 = Linf *{1 – e 2 0 } t1 = t0 – [ln(1 – L 1/Linf)]/K t2 = t0 – [ln(1 – L 2/Linf)]/K w = [1/(L 2 – L1)]*[a/(b+1)] (b+1) (b+1) – L1 ] *[L2 F = (t 2 – t1).S.q.X M = (t 2 – t1).M' [–(F+M)] N2 = N1.e N = (N 1 – N2)/(F+M) Cn = F.N D = M.N Cw = Cn.w n = 1000/w Cn' = sum(Cn) Cw' = sum(Cw) CR = Cw'/X w' = Cw'/Cn'

Economic component: Shrimp price (US$ 1000/ton) Catch value (USD 1000) Gross revenue Fishery cost Fishery profit

Pr Gr GR FC PR

Pr = u.e Gr = Cw'.Pr GR = sum(Gr) FC = X.C PR = GR – FC

(v.n)

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16) (17)

(18) (19) (20) (21) (22)

Remarks: k = length class of shrimp size (cm); S = selection ogive at length class k; M’ = annual natural mortality; N1 = start population number (million) at length class k; X = annual fishing effort (no. of vessels); Equations (1) – (12), (14) – (17) and (19) – (22) are from Sanders (1993, 1995).

Table 2. The value of input parameters used in the analysis Input parameters Asymptotic length (cm) -1 Curvature coefficient (yr ) Age at zero length (yr) Length at recruitment (cm) Length at first capture (cm) Length-weight equation constants Catchability coefficient Intrinsic growth rate 3 maximum (virgin) population (10 tonnes) Annual fishing effort (no. of vessels) 3 total fishing costs (US$ 10 /vessel/yr)

Symbols L inf K to Lr Lc a b q r Binf X C

Values 5.02 1.625 -0.083 1.60 2.45 0.646 2.945 0.001383 1.7021 107.8 421 303.7

Sources Naamin (1984) Naamin (1984) Naamin (1984) Sumiono (pers. comm.) Naamin (1984) Naamin (1984) recalculated Naamin (1984) Purwanto (2008, 2011) Purwanto (2008, 2011) Purwanto (2008, 2011) Purwanto (2011) Purwanto (2008, 2011)

The coefficient of annual natural mortality (M’) was estimated by using an equation formulated by Pauly’s empirical formula (Sparre & Venema, 1998) as follows:

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Ln M’ = – 0.0152 – 0.279*ln Linf + 0.6543*ln K + 0.463*ln T ................................... (23) Where T is the annual mean habitat temperature (oC) of the water in which the shrimp stock lives. The T in the Arafura Sea was about 280C (Sumiono, pers. comm.). The annual recruitment was assumed to be constant. Therefore, the estimates of yields, etc. are equilibrium values. The recruit number of shrimp stock at zero age (R) was estimated on the basis of yield (Y) and yield per recruit (Y/R) as follows: R = Y/(Y/R) ............................................ (24)

Yield of shrimps can be estimated by using a fishery production model (Anderson & Seijo, 2010) as follows: Y = F’*B .................................................. (25) Where: F’ B F’ Q Binf

= q.X = Binf * (1 – F’/r) = annual fishing mortality; = catchability coefficient; = maximum population which the living space and food supply support; = intrinsic growth rate.

r

Meanwhile, yield per recruit can be estimated by using a model developed by Beverton & Holt (1957). A length-based version of the yield per recruit model (Sparre & Venema, 1998) was used in the analysis as follows: Y/R = F*A*W inf * [1/Z – 3U/(Z+K) + 3U2/ (Z+2K) – U3/(Z+3K)] ................. (26)

Where: A W inf U Z

= [(Linf – Lc)/(Linf – Lr)]M/K = a.Linf b = 1 – Lc/Linf = M’ + F’.

The price of shrimps is a function of shrimp size (equation 18). The parameters of the price equation were estimated by ordinary least square using data from Indonesian Shrimp Fishery Association.

82

RESULTS The annual natural mortality of the shrimp stock was estimated to be about 1.9566. The recruitment of shrimp stock in Arafura Sea in 2008 was estimated to be about 9359 million individual shrimps. Meanwhile, the price of shrimps was statistically affected by the shrimp size. The relationship between price and size of shrimps was represented by the following equation: Pr = 11.2098*e–0.0205*n

(18.1)

The peformance of fishery harvesting shrimps with the shortest carapace length (CL) of 16 mm in year 2008, when the number of fishing vessels was 421 units creating fishing mortality of about 0.58, is presented in Table 3. The estimated number of shrimps harvested was about 1577 million, with the mean length and weight of 29 mm CL and 20 grams respectively. Meanwhile, the estimated number of shrimps died caused by natural mortality was about 7780 million. The estimates of total catch weight and value were about 30.8 thousand tonnes and US$ 162 million per year, respectively. As the cost of fishing was US$ 128 million per year, the estimate of total profit was about US$ 34 million per year (Tables 3 & 4). Comparing the estimates of fishery performance for a range of annual fishing mortality, as presented in Table 4, vessel productivity decreased with increasing fishing mortality. Similarly, shrimp size decreased, which in turn decreasing shrimp price, when fishing mortality increased. Profit per vessel also decreased with increasing fishing mortality even at the low level of shrimp stock utilisation (Fig. 1). Further increase in fishing mortality could result in economic loss. Meanwhile, the total profit to the shrimp fishery in the Arafura Sea increased with increasing fishing mortality when the utilisation of shrimp stock was at the low level. The fishery resulted in the optimum profit (US$ 44.5 million/yr) when fishing mortality was about 0.36 and the size at first capture of shrimps was 16 mm CL (Table 4, Fig. 1). The estimated catch of shrimps at the optimum total profit was about 22.4 thousand tonnes/year with the mean length of 30 mm CL and weight of 21 grams. After achieving the optimum total profit, increases in fishing mortality decreased total profit. Further increase in the fishing mortality could also result in economic loss.

Table 3. Estimates of population, catch, exploited biomass, price and value of shrimps in the Arafura Sea

Performance of A Fishery Harvesting Different Minimum Shrimp Sizesi in The Arafura Sea (Purwanto)

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Table 4. Estimates of fishery performance for a range of annual fishing mortality Catch weight (103 t /yr)

Fishing mortality

Total revenue and total cost (US$ million/yr)

F 0.06 0.11 0.17 0.22 0.28 0.33 0.36 0.39 0.44 0.50 0.55 0.58 0.61 0.66 0.72 0.77 0.83 0.89 0.94

Catch rate (t/vessel /yr)

Cw' 4.4 8.4 12.1 15.4 18.4 21.1 22.4 23.6 25.9 28.0 29.8 30.8 31.6 33.1 34.5 35.8 37.0 38.1 39.0

Mean caparace length (mm)

Mean shrimp weight (gm)

Gross revenue (USD 6 10 /yr)

Fishery cost (USD 6 10 /yr)

cl 31.3 31.0 30.8 30.6 30.4 30.2 30.1 30.0 29.8 29.6 29.5 29.4 29.3 29.1 28.9 28.8 28.6 28.4 28.3

w' 23.4 23.0 22.5 22.1 21.6 21.2 21.1 20.8 20.4 20.1 19.7 19.6 19.4 19.0 18.7 18.4 18.1 17.8 17.5

GR 25.8 48.6 68.9 86.9 102.8 116.8 123.4 129.2 140.1 149.6 158.0 162.2 165.2 171.5 176.9 181.5 185.5 188.7 191.4

FC 12.1 24.3 36.4 48.6 60.7 72.9 79.0 85.0 97.2 109.3 121.5 127.9 133.6 145.8 157.9 170.1 182.2 194.4 206.5

Cw'/X 110.5 105.4 100.7 96.2 92.0 88.1 86.3 84.4 80.9 77.7 74.6 73.2 71.7 69.0 66.4 64.0 61.7 59.5 57.4

200 160 120 80 40 0 -40

0,0

0,2

0,4

0,6

0,8

Fishing mortality

-80 Total revenue Total profit

Total cost Profit per vessel

Figure 1. Total revenue, total cost and total profit to shrimp fishery in the Arafura Sea, when recruitment, length at first capture of shrimp stock and natural mortality were 9359 million recruits, 16 mm CL and 1.96 respectively.

84

Fishery profit (USD 106/yr) PR 13.6 24.3 32.5 38.3 42.1 43.9 44.5 44.2 42.9 40.3 36.5 34.4 31.6 25.7 19.0 11.5 3.2 -5.6 -15.1

The impact of different minimum shrimp sizes, as indicated by the carapace length at first capture, on vessel productivity and production of shrimps from the Arafura fishery can be estimated and presented in Figure 2 a&b, respectively. The relationships between vessel productivity and fishing effort at different sizes at first capture of shrimps were not different, the productivity declined with increasing fishing effort. Comparing productivity of vessels harvesting different first capture sizes at the fishing effort of year 2008, the highest productivity of fishing vessels was achieved when the smallest size of shrimps harvested was about 22 mm CL. Further, the highest shrimp production at the fishing mortality of year 2008 was also achieved when the shortest size of shrimps harvested was about 22 mm CL. Similar to the vessel productivity, profit per vessel of shrimp fishery in the Arafura Sea also declined with increasing number of fishing vessels, but the amounts of per vessel profit were different depending on the first capture sizes of shrimps. Comparing the estimated profit gained by fishery from operating 421 vessels harvesting different first capture sizes, the

Performance of A Fishery Harvesting Different Minimum Shrimp Sizesi in The Arafura Sea (Purwanto)

highest profit per vessel (i.e. US$ 131 thousand/yr) resulted from harvesting shrimps when the smallest size was about 28 mm CL (Figure 3). When natural mortality decreased to 1.65, the estimated profit per vessel increased to US$ 173 thousand per year although the number of fishing vessels operated and

(a)

Production (1000 tonnes/yr)

Vessel productivity (tonnes/yr)

115 105 95

X 2008

85

the smallest size of shrimps harvested didnot change, namely 421 units and 28 mm respectively. If natural mortality increased to 2.45, the estimated profit per vessel decreased to US$ 70 thousand/yr when the number of fishing vessels operated and the smallest size of shrimps harvested didnot change.

75 65 55 45

(b)

40

F’2008

35 30 25 20 15 10

0

200 400 600 Fishing effort (No. of vessels) LC-10mm LC-22mm LC-28mm LC-32mm

LC-16mm LC-26mm LC-30mm LC-37mm

0,2

0,4 0,6 0,8 Fishing mortality LC-10mm LC-22mm LC-28mm LC-32mm

1,0

LC-16mm LC-26mm LC-30mm LC-37mm

400

(M’=1.96)

320 240 160

400

(M’=1.65)

320 240 160 80

80 0 200 400 600 Number of vessels

LC-10mm LC-22mm LC-28mm LC-32mm

LC-16mm LC-26mm LC-30mm LC-37mm

400 320

(M’=2.45)

240 160

0 0

-80

480

80

0 0

-80

480

Profit per vessel (US$ 1000/yr)

480

Profit per vessel (US$ 1000/yr)

Profit per vessel (US$ 1000/yr)

Figure 2. Impacts of different minimum shrimp sizes (LC-...) harvested by fishery in the Arafura Sea on: (a) the vessel productivity at different fishing effort levels, and (b) the production at different fishing mortality levels. (Remark: X2008 & F’2008 = level of fishing effort & fishing mortality in year 2008).

200 400 600 Number of vessels

LC-10mm LC-22mm LC-28mm LC-32mm

LC-16mm LC-26mm LC-30mm LC-37mm

0 -80

200 400 600 Number of vessels

LC-10mm LC-22mm LC-28mm LC-32mm

LC-16mm LC-26mm LC-30mm LC-37mm

Figure 3. Impacts of different minimum shrimp (LC-...) sizes harvested by fishery in the Arafura Sea on the profit per vessel at different fishing effort levels (number of vessels), when natural mortality (M’=...) was 1.96, 1.65, and 2.45.

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As presented in Figure 1, there was an optimal fishing mortality, i.e. a certain level of fishing mortality that resulted in the optimum total profits. The optimal fishing mortality of shrimp fishery in the Arafura Sea varied with the first-capture sizes of shrimps. When natural mortality was 1.96, the fishery would result in the optimum total profit, amounting to about US$ 56.3 million/yr, if the first-capture size of shrimps was 29 mm CL harvested at fishing mortality 0.50 (Figure 4). At the first-capture size of shrimps of 29 mm CL and fishing mortality 0.50, decreasing natural mortality from 1.96 to 1.65 resulted in higher total profit, amounting to US$ 74.0 million/yr. When natural mortality decreased, it was more economical to harvest shrimps at the larger size. At natural mortality 1.65, the optimum total profit would be about US$ 74.7 million/yr when the smallest size of shrimps caught and fishing mortality were 30 mm and 0.55 respectively (Figure 4). On the contrary, it was more economical to harvest shrimps at the smaller size when natural mortality increased. If natural mortality increased to 2.45, the optimum total profit would be about US$ 32.5 million/yr when fishery harvested shrimps at the first-capture size of 26 mm CL and fishing mortality 0.41 (Figure 4). DISCUSSION This paper demonstrates the impact of harvesting different minimum sizes of shrimps at various fishing and natural mortalities on the performance of a fishery in the Arafura Sea. Fishing is basically an economic activity, that is conducted to gain profits. The optimal total profit to fishery resulted from harvesting a certain first-capture size of shrimps at a certain fishing mortality. As the estimates of recruitment and natural mortality in 2008 were 9359 million recruits and 1.96 respectively, the optimum total profit would be achieved if the first-capture size of shrimps and fishing mortality were 29 mm CL and 0.50 respectively. The total profit to the fishery would be sub-optimal when the size of shrimps at first-capture was smaller than that optimal size. Similarly, the total profit was also sub-optimal when the size of shrimps at first-capture was larger than that optimal size. The size at first capture and the smallest size of shrimps caught by shrimp trawlers in the Arafura Sea in 1982 were 24.5 and 21.5 mm CL, respectively (Naamin, 1984). Meanwhile Sumiono and Hargiyanto (pers. comm), from their observation in 2011, informed that the smallest size of shrimps harvested by trawlers in the Arafura Sea were 16 - 17 mm CL. Further, fishing

86

pressures to the shrimp stock in the Arafura Sea resulted not only from the operation of trawlers but also from the operation of small scale fishery in coastal areas harvesting juvenile and pre-adult cohorts. These data and information indicated the possibility of the first capture size of shrimps harvested from the Arafura Sea in 2011 to be smaller than that in 1982. These also indicated that shrimp fishery in the Arafura Sea was economically in a sub-optimal condition. From an economic point of view, the fishing activity targeting shrimp stock should be controlled to ensure that fishery gains optimum profit. Furthermore, from a biological point of view, it would be beneficial to the sustainability of stock when a cohort of shrimps has chance to grow to the optimal size and to produce offsprings before harvested. Therefore, effort should also be undertaken to make sure that the size at first capture is larger than the size at maturity. The optimum first capture size estimated in this study (29 mm CL) is larger than the estimate of the size at maturity, i.e about 25.9 mm CL (Naamin, 1984). Therefore, a fishery management policy that controls fishing activity to harvest shrimps at the first capture size of 29 mm CL and the fishing mortality of 0.50 would ensure the optimum level of shrimp fishery. This study also demonstrated that variation in the natural mortality resulted in different optimum levels of first capture size of shrimps and total profit to the fishery. When natural mortality decreased, it was more economical to harvest shrimps at the larger size and higher fishing mortality, accommodating more vessels, and resulting in higher total profit. On the contrary, it was more economical to harvest shrimps at the smaller size when natural mortality increased (Fig. 4). In the last condition, the fishery could accommodate fewer vessels and gain lower total profit. The natural mortality is caused by all other factors than fishing, for example predation, diseases, spawning stress, starvation, and old age The rate of natural mortality rate, caused by predation and starvation for example, are linked to the ambient ecosystem (Sparre & Venema, 1998). The ecosystem, therefore, should be maintained, in conjunction with controlling fishing activity, to sustain shrimp stock and to optimise fishery profit. Further, improvement of the ecosystem would result in higher benefits. Mangroves in the coastal areas are the important part of the ecosystem functioning as nursery site of shrimps. Staples & Vance (1986), Pauly & Ingles (1986), Baran & Hambrey (1998) and Loneragan et al. (2005) reported the positive correlation between the size of mangrove areas and the quantity of shrimps harvested by commercial fishery.

(M’=1.96) 60

40

20

Total profit (US$ million/yr)

80

Total profit (US$ million/yr)

Total profit (US$ million/yr)

Performance of A Fishery Harvesting Different Minimum Shrimp Sizesi in The Arafura Sea (Purwanto)

80

60

40

20

80

60

(M’=2.45)

40

20

(M’=1.65) 0

0 0,1

0,3 0,5 0,7 Fishing mortality

0 0,1

0,9

0,3 0,5 0,7 0,9 Fishing mortality

-20

-20 LC-10mm LC-22mm LC-29mm LC-37mm

LC-16mm LC-26mm LC-32mm

0,1

0,3 0,5 0,7 Fishing mortality

0,9

-20 LC-10mm LC-22mm LC-28mm LC-32mm

LC-16mm LC-26mm LC-30mm LC-37mm

LC-10mm LC-22mm LC-28mm LC-32mm

LC-16mm LC-26mm LC-30mm LC-37mm

Figure 4. Impacts of different minimum shrimp sizes (LC-...) harvested by fishery in the Arafura Sea on the total profit gained at different fishing mortality levels, when natural mortality (M’=...) was 1.96, 1.65 and 2.45. CONCLUSION 1. The optimal total profit to fishery resulted from harvesting a certain first-capture size of shrimps at a certain fishing mortality. The total profit to the fishery would be sub-optimal when the size of shrimps at first-capture was smaller or larger than the optimal size; 2. In the bio-economic condition of year 2008, the fishery achieved the optimal total profit when the size of shrimps at first-capture and fishing mortality were 29 mm CL and 0.50 respectively; 3. The variation in the natural mortality resulted in different optimum levels of first capture size of shrimps and total profit to the fishery. When natural mortality decreased, it was more economical to harvest shrimps at the larger size and higher fishing mortality, accommodating more vessels, and resulting in higher total profit. On the contrary, it was more economical to harvest shrimps at the smaller size when natural mortality increased. REFERENCES Anderson, L.G. & J.C. Seijo. 2010. Bioeconomics of Fisheries Management. Wiley – Blackwell, Ames. 305 p.

Badrudin, B. Sumiono & N. Wirdaningsih. 2002. Laju tangkap, hasil tangkapan maksimum (MSY), dan upaya optimum perikanan udang di Laut Arafura. J. Penelitian Perikanan Indonesia, 8 (4): 23-29. Bailey, C., A. Dwiponggo, & F. Marahudin. 1987. Indonesian marine capture fisheries. ICLARM Studies and Reviews 10. Baars, M.A., A.B. Sutomo, S.S. Oosterhuis, & O.H. Arinardi. 1990. Zooplankton abundance in the eastern Banda Sea and northern arafura sea during and after the upwelling season, August 1984 and February 1985. Netherlands Journal of Sea Research, 25 (4): 527-543. Baran, E., & J. Hambrey, 1998. Mangrove Conservation and Coastal Management in Southeast Asia: W hat Impact on Fishery Resources? Marine Pollution Bulletin. 37 (8-12): 431-440. Cadee, G.C. 1988. Organic carbon in the upper 100 m and downward flux in the Banda Sea; monsoonal differences. Netherlands Journal of Sea Research. 22 (2): I09-121. Caillouet Jr., C.W., R.A. Hart, & J.M. Nance, 2008. Growth overfishing in the brown shrimp fishery of Texas, Louisiana, and adjoining Gulf of Mexico EEZ. Fisheries Research. 92: 289–302.

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Loneragan, N.R., N. Ahmad Adnan, R.M. Connolly, & F.J. Manson, 2005. Prawn landings and their relationship with the extent of mangroves and shallow waters in western peninsular Malaysia. Estuarine, Coastal and Shelf Science. 63: 187– 200. Naamin, N. 1984. Dinamika populasi udang jerbung (Penaeus merguiensis de Man) di perairan Arafura dan alternatif pengelolaannya. Disertasi Doktor. Fakultas Pasca Sarjana. institut Pertanian Bogor. 281 p. Nagelkerken, I., S.J.M. Blaber, S. Bouillon, P. Green, M. Haywood, L.G. Kirton, J.-O. Meynecke, J. Pawlik, H.M. Penrose, A. Sasekumar, & P.J. Somerfield. 2008. The habitat function of mangroves for terrestrial and marine fauna:Areview. Aquatic Botany. 89: 155–185. Najmudeen, T.M., & R. Sathiadhas, 2008. Economic impact of juvenile fishing in a tropical multi-gear multi-species fishery. Fisheries Research. 92: 322– 332. Pauly, D. 1994. From growth to malthusian overfishing: Stages of fisheries resources misuse. SPC Traditional Marine Resource Management and Knowledge Information Bulletin. 3: 7-14. Pauly, D., & J. Ingles, 1986. The relationship between shrimp yields and intertidal vegetation (mangrove) area: a reassessment. In: Yanez-Arancibia, A., Pauly, D. (Eds.), IOC/FAO Workshop on Recruitment in Tropical Coastal Demersal Communities. UNESCO, Paris, p. 277–284. Primavera, J. H., 1997. Fish predation on mangroveassociated penaeids: The role of structures and substrate. Journal of Experimental Marine Biology and Ecology, 215: 205–216. Primavera, J. H., 1998. Mangroves as Nurseries: Shrimp Populations in Mangrove and Nonmangrove Habitats. Estuarine, Coastal and Shelf Science, 46: 457–464. Purwanto. 2008. Resource rent generated in the Arafura shrimp fishery. Final Draft. Prepared for the World Bank PROFISH Program. Washington. D.C. 29 p. Purwanto. 2011. A compromise solution to the conflicting objectives in the management of the Arafura shrimp fishery. Ind. Fish. Res. J., 17 (1): 37-44.

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Robertson, A.I. & N. C. Duke, 1987. Mangroves as nursery sites: comparisons of the abundance and species composition of fish and crustaceans in mangroves and other nearshore habitats in tropical Australia. Marine Biology 96: 193-205. Sadhotomo, B., P. Rahardjo & Wedjadmiko. 2003. Pengkajian kelimpahan dan distribusi sumberdaya demersal dan udang di perairan Laut Arafura. Prosiding Forum Pengkajian Stok Ikan Laut 2003. Pusat Riset Perikanan Tangkap, Departemen Kelautan dan Perikanan, Jakarta. Sanders, M.J. 1993. Fishery performance and the value of future entitlements under quota management: A case study of a handline fishery in the southwest Indian Ocean. Fish. Res., 18: 219-229. Sanders, M.J. 1995. Introduction to Thompson and Bell yield analysis using Excel spreadsheets. FAO Fisheries Circular, no. 895. Rome, FAO. 21p. Sparre, P. & S.C. Venema. 1998. Introduction to tropical fish stock assessment. Part 1. Manual. FAO Fisheries Technical Paper, no. 306.1, Rev. 2. Rome, FAO. 407p. Staples, J., & D. J. Vance, 1986. Emigration of juvenile banana prawns Penaeus merguiensis from a mangrove estuary and recruitment to offshore areas in the wet-dry tropics of the Gulf of Carpentaria, Australia. Mar. Ecol. Prog. Ser., 27: 239-252. Tijssen, S.B., M. Mulder, & EJ. Wetsteyn. 1990. Production and consumption rates of oxygen, and vertical oxygen structure in the upper 300 m in the eastern Banda Sea during and after the upwelling season, August 1984 and February/March 1985. Netherlands Journal of Sea Research, 25 (4): 485499. Thompson, W.F. & F.W., Bell, 1934. Biological statistics of the Pacific halibut fishery. 2. Effect of changes in intensity upon total yield and yield per unit of gear. Rep. Int. Fish. (Pacific Halibut) Comm., 8: 49pp. Vance, D. J., M. D. E. Haywood & D. J. Staples, 1990. Use of a Mangrove Estuary as a Nursery Area by Postlarval and Juvenile Banana Prawns, Penaeus merguiensis de Man, in Northern Australia. Estuarine, Coastal and Shelf Science, 31: 689-701.

Performance of A Fishery Harvesting Different Minimum Shrimp Sizesi in The Arafura Sea (Purwanto)

Vance, D. J., M. D. E. Haywood, D. S. Heales, R. A. Kenyon, N. R. Loneragan, & R. C. Pendrey. 1996. How far do prawns and fish move into mangroves? Distribution of juvenile banana prawns Penaeus merguiensis and fish in a tropical mangrove forest in northern Australia. Mar. Ecol. Prog. Ser., 131: 115-124. Vance, D. J., M. D. E. Haywood, D. S. Heales, R. A. Kenyon, N. R. Loneragan, & R. C. Pendrey. 2002. Distribution of juvenile penaeid prawns in mangrove forests in a tropical Australian estuary, with particular reference to Penaeus merguiensis. Mar. Ecol. Prog. Ser., 228: 165-177. Wetsteyn, F.J., A.G. Ilahude, & M.A. Baars. 1990. Nutrient distribution in the upper 300 m of the eastern Banda Sea and northern Arafura Sea

during and after the upwelling season, August 1984 and February 1985. Netherlands Journal of Sea Research, 25(4): 449-464. Widodo, J., Purwanto & S. Nurhakim. 2001. Evaluasi Penangkapan Ikan di Perairan ZEEI Arafura: Pengkajian sumberdaya ikan demersal. Direktorat Jenderal Perikanan, Departemen Kelautan dan Perikanan. Jakarta. Wyrtki, K. 1961. Physical Oceanography of the Southeast Asian Waters. NAGA Rep., 2: 195 pp. Keputusan Menteri Kelautan dan Perikanan nomor 45/Men/2011 tentang Estimasi Potensi Sumberdaya Ikan di W ilayah Pengelolaan Perikanan Negara Republik Indonesia.

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Stock Enhancement In Indonesian Lakes and Reservoirs Fisheries (Kartamihardja, E.S.)

STOCK ENHANCEMENT IN INDONESIAN LAKE AND RESERVOIRS FISHERIES Endi Setiadi Kartamihardja Research Center for Fisheries Management and Fish Resources Conservation Received March 27-2012; Received in revised form December 3-2012; Accepted December 4-2012 E-mail: [email protected]

ABSTRACT A total water surface area of lakes and reservoirs of Indonesia is 2.3 million hectares. To increase fish production in Indonesian lakes and reservoirs, fish stock enhancement were practiced. A review on fish stock enhancement in Indonesian lakes and reservoirs was conducted. Some species used in stock enhancement were reviewed, and the causes of program success or failure were analyzed in an attempt to determine the best approach for future stocking. Since 2000 the success of the project on fish stock enhancement were supported by basic research on diet, ecological niche, life cycle and behavior of the species stocked. Recent successes in fish stock enhancement are mainly determined by species which can be reproduced naturally in the water bodies. Nile tilapia (Oreochromis niloticus), Siamese cat fish (Pangasionodon hypophthalmus) and small carp (bilih, Mystacoleucus padangensis), an endemic species are the species have best performances in the increasing fish production significantly. Milk fish (Chanos chanos) stock enhancement can be used to mitigate the negative impact of cage culture in the reservoir. While grass carp (Ctenopharyngodon idellus) has been successful in controlling aquatic weed, Eichhornia crassipes in some lakes. Management of fish stock enhancement including providing quality and quantity of seeds, regulating of fish catch, developin g of market system, institution and fisheries co-management have supported a steady yearly increase in yield. The governments should take the initiative in protection of genetic diversity, especially in stock enhancement of lakes inhabited by endemic and or threatened species, such as lakes in Sulawesi and Papua Island. Key words: Stock enhancement, management, fisheries, lake, reservoir, Indonesia

INTRODUCTION A total water surface area of inland open waters of Indonesia is 14.3 million hectares; compose of rivers and flood plains 12 million hectares, lakes 1.8 million hectares and man-made lakes or reservoirs 0.5 million hectares. Indonesia has around 840 lakes and 735 “situ” (small lakes) and around 162 reservoirs (Kartamihardja, 2006). About 80% of the total area of reservoirs is located in Java Island, an island densely population, while the lakes were mostly distributed in large island, i.e., Sumatera, Kalimantan, Sulawesi, and Papua (Sukadi & Kartamihardja, 1995). The Indonesian lakes and reservoirs were utilized by multi-sectors such as source of water for industrial and household, agriculture irrigation, hydro-electric power generation, fisheries, and eco-tourism. Fisheries activities in lakes have been conducted for a long time ago, while reservoir fisheries have been developed since the reservoirs impounded. Stock enhancement activity in the mean of fish introduction has been conducted since Dutch colonization. Only some fish have been established and affected the fish yield (Sarnita, 1986).

In 2009, the Ministry of Marine Affairs and Fisheries of Republic of Indonesia has a vision: “Indonesia has become the biggest fisheries production by the year 2015”. As consequences the fish production in lakes and reservoirs should also be increased to support this vision. Increasing the fish production in lakes and reservoirs can be done through stock enhancement techniques. This paper aimed to review the fish stock enhancement practiced, and to analyze the causes of program success or failure in an attempt to determine the best approach for future stocking. MATERIALS AND METHODS Data and information on fish stock enhancement were collected based on literature review and research results conducted by the Agency for Marine and Fisheries Research and Development. Some cases of scientific bases on stock enhancement which affected significantly on the increasing fish yield as well as mitigating and rehabilitation of the waters environment were also analyzed. Secondary data on trend of fish production were collected from Indonesian Fisheries Statistical Data of Ministry of Marine Affairs and Fisheries, Republic of Indonesia. The data were

_________________ Corresponding author: Research Center for Fisheries Management and Conservation Jakarta Jl. Pasir Putih I Ancol Timur, Jakarta Utara

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tabulated and then analyzed descriptively using the Excel program. Some factors causing the stock enhancement program success or failure were identified and discussed in attempt to determine the best approach for future development. RESULTS Limnological Characteristics of Lakes and Reservoirs The latest limnological characteristics of major lakes and reservoirs has been reviewed through Expedition Indodanau in 1995 (Lehmusluoto & Machbub, 1997), after that there is no comprehensive research conducted, only sporadically done for some lakes and reservoirs when begin to support fisheries Kartamihardja et al., 1992). The morphometric and trophic level of major lakes is presented in Table 1.

The large and deep lake mostly classified into volcanic, tectonic or crater lake which are located in Sumatera, Sulawesi and Papua. Toba Lake is the largest lake with a surface water area of 112,000 hectares, while the Towuti Lake is the deepest lake (590 m) in Indonesia. Most of the tectonic, volcanic and crater lakes are low productive lakes which were classified into oligotrophic and mesotrophic lakes. On the contrary, the floodplain lakes, which mostly located in Kalimantan are shallow productive lakes and were classified into meso- to eutrophic waters. Trophic level of some lakes, such as Toba and Maninjau Lakes tend to increase as a result of waste loading from intensive cage fish culture. Generally, the reservoirs are more productive than the lakes. Morphometric characters and trophic level of man-made lakes or reservoirs is presented in Table 2.

Table 1. Morphometric and trophic level of major Indonesian Lakes (Kartamihardja, 2009; Lehmusluoto & Machbub, 1977; Sukadi & Kartamihardja, 1995) Island / Lake

Area (ha)

Depth (m)

Altitude (m asl)

Type

Trophic Level

SUMATERA: Laut Tawar Toba Maninjau Singkarak Diatas Dibawah

7,000

80

1100

112,000

500

905

Tectonic

Mesotrophic

Tecto-Volcanic

Mesotrophic

9,790

180

459

Caldera

Mesotrophic

10,780 3,600

80 36

360 1100

Tectonic Tectonic

Mesotrophic Oligotrophic

1,200

80

800

Tectonic

Mesotrophic

12,590

229

540

Tectonic

Mesotrophic

6,000

45

900

Tectonic

Mesotrophic

Luar

15,000

6

25

Floodplain

Mesotrophic

Genali

18,000

6

24

Floodplain

Eutrophic

7,600

10

15

Floodplain

Mesotrophic

Jempang

15,000

5

10

Floodplain

Eutrophic

Semayang Melintang SULAWESI:

12,000 9,000

5 5

10 10

Floodplain Floodplain

Eutrophic Eutrophic

Floodplain

Ranau Kerinci KALIMANTAN:

Sembuluh

Limboto

3,500

4

15

Tondano

6,000

30

600

Crater

Mesotrophic

Poso Lindu

32,300 3,150

450 100

485 9

Tectonic Tectonic

Oligotrophic Oligotrophic

Tempe

10,000

5

5

Towuti

56,100

203

382

Tectonic

Oligotrophic

Matana B A L I:

16,500

600

293

Tectonic

Oligotrophic

1,590

80

1031

Caldera

Oligotrophic

Batur IRIAN/PAPUA: Sentani

Eutrophic

9,360

50

70

Landslide

Mesotrophic

14,150

20

1742

Tectonic

Oligotrophic

Ayamaru Yamur

2,200 3,750

td td

250 90

Tectonic Tectonic

Oligotrophic Oligotrophic

Tage

2,400

td

1750

Tectonic

Oligotrophic

Tigi

3,000

td

1740

Tectonic

Oligotrophic

Paniai

92

Floodplain

Eutrophic

Stock Enhancement In Indonesian Lakes and Reservoirs Fisheries (Kartamihardja, E.S.)

Table 2. Morphometric and trophic level of major Indonesian reservoirs (Kartamihardja, 2009; Lehmusluoto&Machbub, 1977; Sukadi & Kartamihardja, 1995) Province/Reservoir

Area (ha)

Depth (m)

Altitude (m asl)

Trophic Level

Impounded Purposes

West Jawa: Saguling

5340

90

625

Hyper-eutrophic

1985 – FEI

Cirata

6200

106

250

Hyper-eutrophic

1987 – FEI

Jatiluhur

8300

95

110

Hyper-eutrophic

1965 – DFEI

Darma Central Jawa: Wonogiri

400

12

70

Meso-eutrophic

1962 – I

6480

28

140

Meso-eutrophic

1981 – IFE

Wadaslintang

1460

85

115

Mesotrophic

1987 – IFE

Kedungombo

6100

50

100

Mesotrophic

1989 – IFE

Mrica

1500

231

Mesotrophic

1989 – EFI

Sempor East Jawa: Karangkates

300

45

77

Mesotrophic

1978 – IEF

1500

70

270

Mesotrophic

1972 – IEF

400 260 380 570 290

46 50 28 10 24

600 300 163 11 296

Mesotrophic Mesotrophic Mesotrophic Mesotrophic Mesotrophic

1970 – IEF 1977 – IEF 1977 – IEF 1983 – IF 1987 – EI

Selorejo Lahor Wlingi Bening Sengguruh Nusa Tenggara Barat: Batujai South Kalimantan: Riam Kanan

890

14

4

Mesotrophic

1983 – I

9200

50

25

Mesotrophic

1983 – IEF

Lampung: Way Rarem

1400

25

60

Mesotrophic

1982 – IF

Way Jepara 220 ? 60 Mesotrophic Remarks: I = irrigation; F = flood control; E = electric power; D = drinking water

1976 – IF

Potential Yield And Fish Diversity Of Lakes And Reservoirs Potential yield of lakes and reservoirs of Indonesia has been estimated using primary productivity and or morpho-edaphic index (a ratio between conductivity and mean depth) approach (Moreau&DeSilva, 1991; Oglesby, 1982) (Kartamihardja, 2009). For that purposes, a total number of 27 lakes samples and 46 reservoirs samples were classified into three groups, i.e. large, medium and small water body. The large water body of lakes are lakes with a surface water area more than 10,000 ha; medium water body has a surface water area between >5000-10,000 ha; and small water body has a surface water area between >1000-5000 ha. The large, medium and small lakes has an average of estimated potential yield of 178.8±67.1; 207.6±62.2; and 71.6±36.4 kgs/ha/yr,

respectively. For the reservoir, the large water body has a surface water area >1000-10,000 ha, medium reservoir has a surface water area between >200-1000 ha, and small reservoir has a surface water area between 0.5-200 ha. The large, medium and small reservoirs have an average of estimated potential yield 683.5±229.1; 1328.8±485.7 and 2793.7±1022.9 kgs/ ha/yr, respectively. The relationship between potential yield and area of lakes and reservoirs are presented in Figure 1 and 2. The equations were used to estimate the potential fish of the individual lake and reservoir for fisheries development, especially in stock enhancement techniques. Based on these data and information, Kartamihardja, (2009) also estimated the total potential yield of the Indonesian lakes being 328,804 tones/year and reservoirs being 385,304 tones/year.

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Potenial Yield (kg/ha/yr)

1200

y = 485527x-0,775 R² = 0,5318; N=12

(a)

200

(a)

800 600 400 200

1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 Reservoir area (ha)

300 250

y = 15140x-0,384 R² = 0,8055; N=10

1000

0

Potenial Yield (kg/ha/yr)

Potential Yield (kg/ha/yr)

Indonesia divides into two ecological regions; western Indonesia is more influenced by Asian fauna, and the east is more influenced by Australasian. Zoogeographically, fish resources of inland waters of Indonesia are divided into fish inhabit the Sundaland, Wallacea zone and Sahulland which were inhabited by more than 1.000 fish species (Kottelat et al., 1995). In the Sunda land more than 358 species of the order Ostariophysi and Labyrinthici dominated inland open waters in Sumatera and Kalimantan (Ondara, 1982).

150 100

3000

y = 37794x-0,565 R² = 0,5046; N=13

2500

(b)

2000 1500 1000 500 0 0

50

200

400

600

800

1000

Reservoir Area (ha)

0 6000 Potential Yield (kg/ha/yr)

10.000 30.000 50.000 70.000 90.000 110.000 Lake area (ha) Potential Yield (kg/ha/yr)

350 y = 789202x-0,930 R² = 0,6372; N=7

300

(b)

250 200

3000 2000 1000 0

100

0

5.000

6.000

7.000

8.000

9.000

10.000

Lake Area (ha) 180 160

y = 35995x-0,806 R² = 0,5719; N=8

140

(c)

120 100 80 60 40 20 0 1.000

50

100

150

200

Reservoir Area (ha)

0

Potential Yield (kg/ha/yr)

4000

150

50

1.500

2.000

2.500

3.000

3.500

4.000

Lake Area (ha)

Figure 1. Relationship between lake area and estimated potential yield Remarks: (a) Large lakes, area: >10.000 ha; (b) Medium lakes, area: >5.000-10.000 ha; (c) small lakes, area: >1.000-5.000 ha

94

(c)

y = 3570,3x-0,126 R² = 0,5011; N=23

5000

Figure 2. Relationship between reservoir area and potential yield Remarks: (a) Large reservoirs, area: 1.000-1.000 ha; (b) Medium reservoirs, area: >200 – 1,000 ha; (c) Small reservoirs, area: 0.5 – 200 ha There are about 310 species of fishes recorded from the rivers and lakes of Wallacea, 75 species of them are endemic. Although little is still known about the fishes of the Moluccas and the Lesser Sunda Islands, 6 species are recorded as endemic. On Sulawesi, there are 69 known species, of which 53 are endemic. The Malili lakes in South Sulawesi, with its complex of deep lakes, rapids and rivers, have at least 15 endemic thelmatherinid fishes, two of them representing endemic genera, three endemic Oryzias, two endemic halfbeaks, and seven endemic gobies. Most of the species inhabit inlandwaters of Indonesia are riverine species and only some species are the lacustrine. Therefore, number of fish species inhabit the lakes and reservoirs generally less than

Stock Enhancement In Indonesian Lakes and Reservoirs Fisheries (Kartamihardja, E.S.)

the species inhabit the rivers. This condition is one of the factors caused fish production in lakes and reservoirs being relatively low due to large the pelagic area was not inhabited by fish. Some species dominated the lakes and reservoirs, generally of the cyprinids family such as genus Puntius/Barbonymus, Hampala, Mystacoleucus, Osteochilus; silurids family such as Mystus, Channa; and chiclids, Oreochromis mossambicus. Fish Stock Enhancement Stock enhancement in the meaning of fish introduction in Indonesian lakes has been conducted since Dutch colonization, since an ancient ago (Sarnita, 1986). More than 17 fish species has been stocked into lakes and reservoir of Indonesia (Sarnita, 1986; Sarnita, 1999). Snake head (Channa striata) is the first species introduced into Indonesia from Southern China in 1915, grass carp (Ctenopharyngodon idella) and mud carp (Cirrhinus chinensis) introduced from Malaysia. Common carp (Cyprinus carpio) now becomes one of culture species delivered from China and Japan in 1920. Fish species stocked in lakes and reservoirs were usually the cultured species such as common carp, Cyprinus carpio; java tilapia (Oreochromis mossambicus; Nille tilapia, O. niloticus; snakeskin gouramy, Thrichogaster pectoralis; and three spot gourami, T. trichopterus; java barb, Barbonymus gonionotus; Bitter dregs fish, Osteochilus hasselti; giant gouramy, Osphronemus gouramy; walking catfish, Clarias batrachus; and kissing gouramy, Helostoma temmincki (Sarnita, 1986). List of the fish species introduced and stocked in Indonesian lakes and reservoirs was presented in Table 3. Java tilapia, Oreochromis mossambicus was introduced to Toba Lake, an oligotrophic and the deep lake in North Sumatera in 1930. The tilapia growth and breed naturally and since 1958 become the dominant species in the total catch. Unfortunately, the java tilapia grow slowly with the body slimmer due to poor of natural food and limitted of littoral habitat (Kartamihardja, 1987). In Indonesian reservoirs, fish stock enhancement generally conducted since the reservoir impounded. The fish species used in the stock enhancement mostly the culture species, such as tilapia (O. mossambicus and O. niloticus), common carp (Cyprinus carpio), giant gouramy (Osphronemus

gouramy), java carp (Barbonymus gonionotus), kissing gouramy (Helostoma temminckii), snakeskin gouramy (Trichogaster pectorallis) and three spot gourami (T. trichopterus). Nile tilpia introduced in the reservoirs, generally showed good performance, spawn naturally and increased the total fish catch, such as its happened in Jatiluhur Reservoir, West Java (Kartamihardja & Hardjamulia, 1985). Between the introduced species, snake head, common carp, snake skin gouramy (Trichogaster trichopterus) and java tilapia (Oreochromis mossambicus) were species which can grow either in some lakes and reservoirs of Indonesia and dominates the fishers catch. In some lakes and reservoirs, fish introduction and restocking has prospected in increasing catch, but in a long term success of restocking practice in the context of environmental balance and its support to the poor is fail. Fish introduction which is not based on precautionary approach and limnological characteristics of the water body would negate impact on the degradation of local fish species. FAO, (1999) reported that through fish stocking and introduction adapted to limnological condition of the water body and ecological balance oriented has increased for about 20% of fish production of the world inland open waters. In Indonesia, some example of fish stocking and introduction being successful is as follows. Introduction of common carp to Lake Tondano in North Sulawesi in period 1985-1991, yielded 60% from total fish catch of 340 kg/ha (Sukadi& Kartamihardja, 1995). In 1937, java barb (B. gonionotus) introduced to lake Tempe in South Sulawesi and in 1940 and 1948 has yielded of 3,650 tonnes and 25,000 tones, respectively (Sarnita, 1986). Total fish production in that lake increasing from year to year and in 19631975, the average fish production reached 900 kgs/ ha/yr (Sarnita, 1999). After 1995, the fish production was dominated by Nile tilapia which was introduced in 1992. Since 1999, stock enhancement of Indonesian lakes and reservoirs was generally based on scientific data and information about productivity and ecological niche of the waters body, structure of fish community, life cycle and biology of the fish stocked (Kartamihardja, 2007). Some successful of fish stock enhancement in some lakes and reservoirs are as follows.

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Table 3. List of fish species introduced and stocked in Indonesian lakes and reservoirs No 1

Common Name Common carp

Scientific Name Cyprinus carpio

Lakes/ Reservoirs L. Toba L. Tempe R. Selorejo

L. Toba

Introduced naturally Introduced naturally Introduced naturally Early 1940

L. Limboto

introduced in 1944, established since 1950 introduced introduced introduced introduced introduced introduced

introduced in 1965, not established introduced in 1920. not established

R. Lahor R. Karangkates 2

Java Tilapia

Oreochromis mossambicus

Remarks In 1905, 1937 found in great number, early 1950 decreasing introduced in 1960-1970, established until 1995

3

Nile tilapia

Oreochromis niloticus

4

Giant gouramy

Osphronrmus gouramy

L. Lindu R. Karangkates R. Selorejo R. Lahor R. Jatiluhur L. Toba

5

Snake skin gourami

Trichogaster pectoralis

R. Jatiluhur L. Toba

in 1971-1980, growth well, not reproduced in 1971-1980, growth well, not reproduced in 1971-1980, growth well, not reproduced in L. Toba, established until 2003;

in early 1950, established in 1979, well established in 1979, well established in 1979, well established in 1965, well established in 1920. not established

L. Tempe

introduced in 1937 and 1940, well established introduced in 1965, not established introduced in 1925. established since 1935

6

Three spot gourami

Trichogaster trichopterus

R. Jatiluhur L. Tondano

7

Bitter dregs fish

Osteochilus hasselti

Crater Lake in Maluku

Introduced in 1929, not established

8

Kissing gouramy

Helostoma temminckii

L. Tempe

introduced in 1925. established since 1940

9

Java carp

Barbonymus gonionotus

L. Tempe

introduced in 1937, well established until 1995

Chanos chanos

R. Lahor R. Jatiluhur

introduced in 1978, established Introduced in 2008, to mitigate a negative impact of cage culture, fast growth

R. Cirata

Introduced in 2008, to mitigate a negative impact of cage culture, fast growth Introduced in 2009, slow growth introduced in 1995/96, succes to control aquatic weed, water hyacinth transflanted in 2003, well established since 2005 and dominated yield introduced in 1999-2003, well established, spawn naturally Introduced in 2007 to mitigate a negative impact of cage culture, fast growth but not prefered as food

10

Milk fish

11

Grass carp

Ctenopharyngodon idella

L. Batur L. Kerinci

12

Bilih fish

Mystacoleucus padangensis

L. Toba

13

Siamese catfish

Pangasionodon hypopthalmus

R. Wonogiri

14

Silver carp

Hypopthalmichthys molitrix

R. Cirata R. Jatiluhur

Giant freshwater prawn (Macrobrachium rosernbergii) introduced in Darma reservoir, West Java in 2003 yielded 337,65 kgs with the value of 13,5 million rupiahs in 2004 even though the seed prawn stocked was only 26,500 tails or 26,5% from the optimum amounts of stocking (Kartamihardja et al., 2004). If the prawn stocking is done optimally, it is estimated that the prawn value production of 70-140 million rupiahs per year would be achieved and be an additional income for 120 fishers. In the period 1999-2002, about 36,450 seeds of Siamese catfish (Pangasionodon hypopthalmus) have been introduced into Wonogiri reservoir in Central Java and since 2003 the catfish production increased gradually. In 2004, the Siamese caught were 112,215 tones which the value equal to 785.5 million rupiahs adding the fisher income for about 1.2 million rupiahs

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Introduced in 2007 to mitigate a negative impact of cage culture, fast growth but not prefered as food

per fisher per year (Kartamihardja and Purnomo, 2004). The Siamese catfish grow fast and this fecundity at the total length between 67.0-82.7 cm and the weight between 3000-5500 grams rranged between 271,700– 1,177,250 eggs (Adjie et al., 2006). The Siamese catfish can spawn naturally and the seed distributed in the mouth of Keduwang and Tirtomoyo River, one of the inlet river. In the period 2005-2010, the Siamese catfish production showed the leveling off, reached between 142.925–191.210 tones as presented in Figure 3. This is indicated that the rate of Siamese catfish recruitment from natural spawning lower than that the rate of Siamese catfish exploitation (Kartamihardja et al., 2011). The introducing bilih fish has been able to provide the positive impact on social and economic aspects of the society surrounding the Lake Toba (Koeshendrajana, 2011).

Siamese catfish catches (Tonnes)

Stock Enhancement In Indonesian Lakes and Reservoirs Fisheries (Kartamihardja, E.S.)

Mitigating the negative impact of intensive cage fish culture using milk fish, Chanos chanos has been conducted in Jatiluhur reservoir, West Java in 20082009. The milk fish fingerling with a total number of 2 millions (in 2008) and 4 millions (in 2009) were multiple stocked in the reservoir. The abundance and biomass of phytoplankton decreased significantly after one month of the stocking. The nutrient of nitrogen and phosphor content were also significantly decreased so that there is no blooming algae which frequently occurred and also the mass died of fish in the cage culture has not been occurred (Kartamihardja et al., 2010a).

200 180 160 140 120 100 80 60 40 20 0

DISCUSSION Figure 3. Siamese catfish (P. hypophthalmus) catches in Wonogiri Reservoir In 2003, bilih fish (Mystacoleucus padangensis), an endemic fish from Lake Singkarak in West Sumatra were introduced to lake Toba in North Sumatra. The species grow and breed naturally and inhabit the pelagic area (Kartamihardja & Purnomo, 2006). Since 2005 the bilih production fastly increases from 653,6 tonnes to be 30,000 tonnes in 2010 as shown in Figure 4 (Kartamihardja & Sarnita, 2010; Wijopriono et al., 2010).

Bilih Catch (Tonnes)

35000 30000 25000 20000 15000 10000 5000

2009

2008

2007

2006

2005

2004

2003

0

Figure 4. Bilih fish, M. padangensis catches in Toba Lake To control aquatic weed, Echhornia crassipes in Kerinci Lake, Jambi, a total number of 28,500 grass carp fingerlings with the total length ranged between 5-12 cm has been introduced in 1995-1996. After two years stocking, nearly 3.000 hectares of water hyacinth covering the lake is clear significantly of the weed (Hartoto & Sumantadinata, 1998).

Lakes and reservoirs of Indonesia has differed limnological characteristics between one water body and the other waters. Its mean that lake characteristics differs from reservoirs characteristics which resulted differences in productivity and potential fish yield. As a result, fish stock enhancement conducted should be adapted to the limnological characteristics of the lake or reservoir. In the deep lake where the area of littoral zone is limited, the fish species stock should be a lacustrine and plankton feeder species which can inhabit the limnetic zone and utilize the plankton abundance. Theoretically, small lake should be highest productivity than medium or large lake but in this case the small lake has lower productivity because the lake samples were crater or caldera lake and deep lakes. The small reservoirs including small shallow lakes, generally have high productivity (potential fish yield) compared to those bigger areas. Stock enhancement in those small water bodies, should be fish introduction and or development of culture based fisheries. The species introduced should be plankton feeder and or herbivore where the fish stocked can utilize the natural food, especially plankton. The bigger reservoirs which were multipurpose reservoir where fisheries placed in the secondary function, stock enhancement activity should include restocking and or introduction of fish species, rehabilitation of spawning habitat and conservation. As stated before, practice of fish stock enhancement through fish stocking and introduction have been done for long time ago. However, fish introduction done generally haves the ceremonial character, only gives the subsidy for fisher and have never been monitored and or was evaluated about the success or the failure (Kartamihardja, 2000). Fish stocking paradigm which only stocked fish without considering limnological condition of the water body,

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preference of the society for the fish and its economics value, possibility that stocking negatively impact on local fish population (Maskur et al., 2010). Until recently, study on the impact of fish introduction on the native fish population as well as on its genetics has not been conducted. For that purposes, the Government should push and support the sound environmentally program as well as study on that matter. For stock enhancement successful, the central management system needs to be changed to involve public participation so that technical management of the fisheries will increase the fish production, ecologically safe, and economically profitable. Some problems come up in the stock enhancement applied in Indonesian lakes and reservoirs are low understanding of stock enhancement by the stake holders; stock enhancement applied has not been based on scientific data and information; fish stocking was done ceremonially by government; number of fish seed stocked was not optimum; hatchery of local species was minimal; impact assessment, monitoring and evaluation have not been conducted; cost-benefit has not been calculated (Kartamihardja et al., 2010b). Campaign of the best practice of stock enhancement to the stakeholders should be conducted before fish stocking was done. The fishers group as a management unit and a key player in the management of the fisheries should be established and educated. In lakes and reservoirs with multipurpose, an integrated management should be applied and management of fishery is a part of management of lakes or reservoirs as a whole (Kartamihardja & Nurhakim, 2005). Management measures of the lakes or reservoirs fisheries should include management of fish population, management of fishery and management of habitat. To know management effectively, periodical monitoring and evaluation need to be done to all production process start from resource aspects, fishery, fish culture, fish harvest, handling, marketing, socio-economic and law enforcement and regulation (Kartamihardja et al., 2010b). Fisheries management developed should be co-management regime with participation of the society. The successful of fish stock enhancement in some lakes and reservoirs of Indonesia have been supported by some factors, i.e., the stocking program was done regularly or the fish stocked can spawn naturally; the seed stocked at an optimum level; regulating of fish catch, developing of market system, strengthen of management institution and implementation of fisheries co-management.

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CONCLUSION Indonesian lakes and reservoirs have different limnological characteristics and also the productivity (potential fish yield). In the future, therefore, the fish stock enhancement should be based on scientific evidence. The Government should facilitate and support in providing local fish seed for restocking purposes. Introduction of fish species should be done with precautionary approach especially in lakes of Sulawesi and Papua inhabited by endemic species. Basic research in lakes and reservoirs productivity, niche ecology, structure of fish community and its trophic level should be conducted. Co-management regime of the lake and reservoir fisheries should be developed. ACKNOWLEDGEMENTS This paper has been presented in the Worshop on Consultation on Development Trends in Fisheries and Aquaculture in Asian Lakes and Reservoirs, held at Wuhan, PR China on 20th-23rd September 2011. I would like to thanks to Prof. Sena S. deSilva, Director General of NACA for giving me opportunity to attend the workshop. REFERENCES Adjie, S., A. D. Utomo, N. Muflikhah & Krismono 2006. Studi Biologi Ikan Jambal Siam (Pangasius hypophthalmus) di Bengawan Solo Bagian Hulu (Study on biology of siamese catfish, P. hypophthalmus in Upper part of Solo River). Pros. Forum Perairan Umum Indonesia III. p. 75-84. FAO (Food and Agriculture Organisation). 1999. Review of the state of world fishery resources: inland fisheries. FAO Fisheries Circular. No. 942. Rome, FAO. 53 p. Hartoto, D.I. & K. Sumantadinata. 1998. Biomanipulation of water hyacinth (Eichhornia crassipes) in Lake Kerinci using grass carp (Ctenopharyngodon idella). 2nd Monograph. Research and Dev Center for Limnology, Indonesian Institute of Sciences. Bogor. 20 p. Kartamihardja, E.S., K. Purnomo, S. Koeshendrajana & C. Umar. 2011. Karakteristik Limnologis, Perkembangan Populasi Ikan Patin Siam (Pangasionodon hypophthalmus) introduksi dan perikanan di Waduk Wonogiri, Jawa Tengah (Limnological characteristics, population growth of stripped catfish, Pangasianodon hypophthalmus introduced and fisheries of Wonogiri Reservoir,

Stock Enhancement In Indonesian Lakes and Reservoirs Fisheries (Kartamihardja, E.S.)

Central Java). J. Kebijak. Perikan. Ind (Indonesian Fisheries Policies Journal). 3 (1): 37-50.

Demersal. Dari Laut untuk Pembangunan. Edisi Maret 2006. Pusdatin, DKP. 8 p.

Kartamihardja, E.S.& A.S. Sarnita. 2010. Populasi Ikan Bilih: Keberhasilan introduksi ikan, Implikasi pengelolaan dan prospek masa depan (Bilih Fish population in Toba Lake: Sucessful fish introduction, management implication and future prosfect). Research Center for Fisheries Management and Conservation, Agency Research and Development for Marine and Fisheries. MMAF Rep. Indonesia. 50 p. (in Indonesia).

Kartamihardja, E.S. 2006. Status Kondisi Lingkungan Perairan Umum Daratan Indonesia sebagai Habitat Ikan (Status of environmental condition of Indonesian Inland open waters as fish habitat). Paper presented in Limnology Forum, Research Center for Limnology, Indonesian Institute of Sciences. Jakarta 6th December 2006. (in Indonesia).14 p.

Kartamihardja E. S., M. Maskur, F. Sukadi, C. Umar, F. B. Davy, Sena S. & De Silva. 2010a. Mitigating Negative Environmental Impact from Intensive Cage Culture Using Stock Enhancement: Case Study on Djuanda Reservoir, West Java Indonesia (inpress). Kartamihardja, E.S., K. Purnomo, D.W.H. Tjahjo, C. Umar, M.T.D. Sunarno & S. Koeshendrajana. 2010b. Petunjuk Teknis, Pemacuan sumberdaya ikan di Perairan Umum Daratan Indonesia (Technical Guideline, Fisheries Enhancement at Inland open waters of Indonesia). Research Center for Fisheries Management and Conservation, Agency Research and Development for Marine and Fisheries. MMAF Rep. Indonesia. 72p. (in Indonesia). Kartamihardja, E.S. 2009. Pendugaan Potensi Produksi Ikan di Perairan Danau dan Waduk Indonesia untuk Pengembangan Perikanan Tangkap (Estimated Potential Fish Yield of Indonesian Lakes and Reservoirs for fisheries development). Technical Report. Research Center for Fisheries Management and Fish Resources Conservation. Agency Research and Development for Marine and Fisheries. MMAF Rep. Indonesia (in Indonesia). 20 p. Kartamihardja, E.S. 2007. Pemacuan stok ikan: Teknologi pilihan untuk meningkatkan produksi perikanan tangkap di Perairan Umum Daratan Indonesia (Fish stock enhancement: optional technology for increasing fisheries production in inland open waters of Indonesia). J. Kebijak. Perikan. Ind. (Indonesian Fisheries Policies Journal). 1 (1): 1-10. Kartamihardja, E.S. & K. Purnomo. 2006. Penyelamatan populasi ikan bilih ke habitatnya yang baru di Danau Toba (Sustaining bilih fish population to a new habitat at Toba Lake).

Kartamihardja, E.S. & S. Nurhakim. 2005. The Need For Integrated Fisheries Management Plan Of Cascade Reservoirs At Citarum River Basin. Paper Presented at the Seminar on Integrated Water Resources Management, January 20, 2005. DGA., Jakarta (unpublish). Kartamihardja, E.S. & K. Purnomo. 2004. Keberhasilan introduksi ikan patin siam (Pangasius hypopthalmus) dan dampaknya terhadap komposisi dan hasil tangkapan ikan di Waduk Wonogiri, Jawa Tengah (The successful of siamese catfish introduced and its impact on fish yield composition at Wonigiri Reservoir, Central Java). Pros. Forum Perairan Umum Ke-1. Balai Riset Perikanan Perairan Umum, PRPT, BRKP, DKP. Kartamihardja, E.S., K. Purnomo, H. Satria, D.W.H.Tjahjo, & S.E. Purnamaningtyas. 2004. Peningkatan stok ikan patin siam (Pangasius hypophthalmus) di Waduk Wonogiri, Ikan baung (Mystus nemurus) di Waduk Wadaslintang dan udang galah (Macrobrachium rosernbergii) di waduk Darma (Stock enhancement of Siamese catfish in Wonogiri reservoir, green catfish in Wadaslintang reservoir and Giant freshwater prawn in Darma reservoir). Pros. Hasil Penelitian Tahun 2004. Pusat Riset Perikanan Tangkap, BRKP, DKP. 159-172. (in Indonesia). Kartamihardja, E.S. 2000. Strategi peningkatan stok ikan di perairan danau dan waduk Indonesia (Strategy of fish stock enhancement in Indonesian lakes and reservoirs). Pros. Semiloka Nasional Pengelolaan dan Pemanfaatan Danau dan Waduk, Jurusan Perikanan Fak. Pertanian UNPAD, Bandung 7 Nopember 2000. 15 p. Kartamihardja, E.S., Krismono & K. Purnomo. 1992. Kondisi Ekologis dan potensi sumber daya perikanan danau dan waduk (Ecological condition and potential fish yield of lakes and reservoirs). Pros. Temu Karya Ilmiah Perikanan Perairan

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Umum, Pengkajian Potensi dan Prospek Pengembangan Perikanan Perairan Umum Sumatera Bagian Selatan, Palembang 12-13 Februari 1992. Puslitbang Perikanan No.26, 1992. Jakarta. p. 37-45. Kartamihardja, E.S. 1987. Potensi produksi ikan dan pengelolaan perikanan Danau Toba (Potential fish yield and fisheries management of Toba Lake). Bull. Penel. Perikanan Darat. 6 (1): 1-10. Kartamihardja, E.S. & A. Hardjamulia. 1985. Konstribusi penebaran ikan nila (O. niloticus) terhadap produksi ikan Waduk Jatiluhur, Jawa Barat (Contribution of Nile tilapia, O. niloticus) stocking to fish production of man-made lake Jatiluhur, West Java). Bull. Pen. Perikan. Darat, 4 (1): 37-40. Koeshendradjana, S. 2011. Kebijakan dan strategi pengelolaan perikanan tangkap di Danau Toba pasca introduksi ikan bilih (Policies and strategies for fishery management in the Toba Lake post introducing of Bilih fish). J. Kebijak. Perikan. Ind. 3 (1): 1-12. Kottelat, M, A.J. Whitten, S.R. Kartikasari & S. Wirjoatmojo. 1995. Freshwater Fishes Of Western Indonesia And Sulawesi, Ikan Air Tawar Indonesia Bagian Barat Dan Sulawesi. Periplus edition (HK) Ltd. 293p+84 plate. Lehmusluoto, P. & B. Machbub. 1977. National Inventory of the major lakes and reservoirs in Indonesia. General Limnology. Revised Ed. Expedition Indodanau Tech. Rep. Res. Inst. Water Resources Dev. Rep of Indonesia and Dept Limnology and Envi. Protect., Univ. Helsinki. Finland, 72 p. Maskur, M., E.S. Kartamihardja & S. Koeshendrajana. 2010. Inland Fisheries Resources Enhancement and Conservation in Indonesia. In M. Weimin, S.S. De Silva and B. Davy (eds). Inland Fisheries Enhancement and Conservation in Asia.

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RAP Publication 2010/22. FAO., UN, Regional Office for Asia and the Pacific, Bangkok. p. 61-76. Moreau, J. & S.S. DeSilva. 1991. Predictive fish yield models for lakes and reservoirs of the Philippines, Sri Lanka, and Thailand. FAO Fish. Tech. Pap. No.319, Rome. Oglesby, R.T. 1982. The mophoedaphic index and reservoir fish production. Trans. Am. Fish. Soc., 111:113-40. Ondara. 1982. Beberapa catatan tentang perairan tawar dan fauna ikannya di Indonesia (Some notes on freshwaters fish fauna of Indonesia). Pros. Seminar Perikanan Perairan Umum, Jakarta, 1921 Agustus 1981. Puslitbang Perikanan, Badan Litbang Pertanian. p. 46-56. Sarnita, A.S. 1986. Introduction and stocking of fish in lakes and reservoirs in Southeast Asian countries with special reference to Indonesia. Reports and Papers presented at the IPFC expert consultation on Inland Fisheries of the Larger IndoPacific Islands. Bangkok Thailand, 4-6 August 1986. FAO Fish. Rep. No. 371 Suppl. FIRI/R371. Sarnita, A.S. 1999. Introduction and stocking of freshwater fishes into inland waters of Indonesia. In: W.L.T. vanDensen & M.J. Morris (eds) Fish and fisheries of lakes and reservoirs in Southeast Asia and Africa. Westbury Pub., Otley, UK. p.143150. Sukadi, M. F. & E.S. Kartamihardja. 1995. Inland fisheries management of lakes and reservoirs with multiple uses in Indonesia. Regional Symposium on sustainable development of inland fisheries under environmental constrains, Bangkok, Thailand, 19-21 October 1994, FAO, UN. Wijopriono, K. Purnomo, E.S. Kartamihardja, & Z. Fahmi. 2010. Fishery resources and ecology of Toba Lake. Ind. Fish. Res, J. 16 (1):7-14.

Size And Fishing Ground Of ………….…… Operated In Indian Ocean (Widodo, A.A. et al.)

SIZE AND FISHING GROUND OF WAHOO (Acanthocybium solandri Cuvier, 1832) FROM CATCH DATA OF TUNA LONGLINE OPERATED IN INDIAN OCEAN 1)

Agustinus Anung Widodo, 2) Fayakun Satria and 3)Budi Nugraha

1) Research Center for Fisheries Management and Conservation Research Institute for Fish Resources Rehabilitation and Conservation 3) Research Station for Tuna Fisheries Received February 2-2012; Received in revised form December 4-2012; Accepted December 5-2012 E-mail: [email protected] 2)

ABSTRACT Wahoo (Acanthocybium solandri Cuvier, 1832) is a member of the Scombrid family, is a pelagic (open ocean) species found worldwide in tropical and warm-temperate seas. It is fished throughout its range by artisanal, recreational, and commercial. Wahoo is one of the by-product species of the tuna long line fleets operate in Indian Ocean. This paper describes status of wahoo resource caught by tuna long line in Indian Ocean based at Benoa-Bali. Data obtained from onboard observer program on the tuna long liner based at Benoa-Bali during 2005-2010. Total of 85 trips of onboard observation were carried out with the total long line sets (one set per day) were 2873 times. The data covered the horizontal and vertical position of tuna long line hooks caught the wahoo, hook rate and fish size distribution. Data of horizontal fishing positions (coordinates) gained from the global positioning system availabled in the tuna long liners. The depth of the long line gear in the waters and teperature of waters were measured by mini-loggers TDR type SP2T-1200, brand: NKE Micrel. Hook rate of wahoo is calculated using the Klawe (1986) method. Result of research showed that the wahoos caught by tuna long lines based at Benoa spread horizontally between 1o31’-33o 40’S and 77o18’117o53’E and spread vertically between the depth of 75.2- 285.7 m. From 85 tuna long line fishing trips, only about 50% of 85 tuna long line fishing trips caught wahoo with hook rate ranged 0.947-1.399 per 1000 hooks/setting. Size distribution of wahoo ranged 70-180cm with modus ranged 101-110cm. Keyword: Wahoo, tuna long line, indian ocean

INTRODUCTION Wahoo (Acanthocybium solandri Cuvier, 1832) is known as Pacific kingfish, tiger fish, ocean barracuda, Malata kingfish, queenfish, kingfish. Fishermen in Hawaii called as ono and peto by fishermen in Karibia. Indonesian fishermen in general called wahoo as tengiri, and tuna long line fishermen in Benoa-Bali called as nyunglas. Collette & Nauen (1983) described the short description of wahoo as follows, number of dorsal spines (D.XXII-XXVII.12-16), no anal spines, anal soft rays (A.12-14), vertebrae 62 - 64. Mouth large with strong, triangular, compressed and finely serrate teeth. Snout about as long as the rest of head. Posterior part of maxilla completely concealed under pre-orbital bone. Gill rakers absent. Inter-pelvic process small and bifid. Swim bladder present. Body covered with small scales. No anterior corselet developed. The back is iridescent bluish green; the sides silvery with 24 to 30 cobalt blue vertical bars which extend to below the lateral line. Wahoo (Acanthocybium solandri Cuvier, 1832), a member of the Scombrid family, a pelagic (open ocean) species found worldwide in tropical and warm-

temperate seas. The wahoo is highly migratory species, widely distributed throughout tropical and subtropical oceans (Collette & Nauen, 1983; Garber et al., 2005; Mc Bride et al., 2008). Roullot & Venkatasami, (1986) mentioned that sports fishermen used troll around FAD reported good catches of tuna, dolfinfish and wahoo. The major non-tuna catch of what could be considered as the three small-scale fisheries in the region targeting tuna (i.e. those in Cape Verde, Morocco and South Africa) show great differences between the countries. Mostly wahoo in Cape Verde mostly Sarda in Morocco, and almost no non-tuna catch by the small-scale tuna fishery in South Africa (Gillet, 2011). In Indonesia wahoo primarily harvested as bycatch in the troll line, drift gillnet, and tuna long line and purse seine fisheries. This paper describes status of wahoo resource caught by tuna long line in Indian Ocean based at Benoa-Bali. MATERIALS AND METHODS Data analyzed were obtained from onboard observer program on commercial tuna long line fleets based at Benoa-Bali in the period August 2005 to October 2010. Mostly tuna longlines technology

_________________ Corresponding author: Research Center for Fisheries Management and Conservation Jakarta Jl. Pasir Putih I Ancol Timur, Jakarta Utara

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based at Benoa are using monofilament line that was first introduced into Indonesia by Taiwanese in 1990s. The principal parts of tuna long line consist of a continuous monofilament main line, with floats and branch lines commonly made of smaller gauge monofilament. Numbers of branch line (hook) in between floats were 12 with interval of each branch lines were 50 m. The lengths of each branch lines are 25-30 meter. The deepest hooks usually reach 400 m with target species yellowfin tuna (Thunnus albacares) and bigeye tuna (Thunnus obesus), whereas wahoo (Acanthocybium solandri) was one species caught as by-product. Total of 85 trips were carried out with the total long line sets (one set per day) 0f 2873 times. The tuna long line equipped with

radio beacons, radar reflectors, and strobe lights are more likely to be used in marking the gear. The depth of the long line gear in the waters and temperature of waters were measured by 6 miniloggers TDR type SP2T-1200, brand: NKE Micrel. The minilogger provide information on depth and water temperature, capable to record water depth up to1200 m and the water temperature -5 to 35 oC. The miniloggers attached in the end of branch lines (clossed to the hooks). The setting configuration of minilogger was attached to the 1st, 2nd, 3rd , 4th, 5th and 6th branch lines respectively on each basket (Figure 1). With this minilogger setting configuration, each depth range would be covered and recorded.

Figure 1. The setting configuration of the minilogger on the branch line of tuna long line during research. Indentification fish species refer to Collete & Nauen (1983), Compagno (1999), Sainsbury et al. (1985) and Sommer et al. (1996). The hook rate was calculated by using the equation of Klawe (1986) as follows:

HR 

JI xA ............................... JP

where : HR JI JP A

(1)

= hook rate. = number of fish caught. = number of hook sets. = 1000.

RESULTS Horizotal and Vertival Distribution Horizontal distribution of wahoo can be described base on result of onboard observer program in 20052010. The wahoo caught by tuna long line based at

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Benoa was between 1o31’ S -33o 40’S and 77o18’E 117o53’E. In 2005-2006, tuna long line based at BenoaBali caught wahoo on 12o S -16oS and 107o E-116o E. In 2007, wahoo caught by tuna long line on the area 11o S -34oS and 97o E -115oE. In 2008, area where wahoos were caught 1o S -15oS and 76o E -116o E, whereas in 2009 wahoo caught on the area 1oS-14oS and 96oE-117oE. In 2010 wahoo caught in area 1o S 13oS and 96oE-120oE (Figure 2). The information on vertical distribution of wahoo was identified through the depth of hook which caught the wahoo. The longline fishing experiment appears as a relevant methodology to achieve this goal (Bach et al., 2003). Installation the miniloger on the branch line of tuna long line has been widely used to obtain the information of vertical distribution as used in this research. Result of research show that the wahoo caught by tuna long line spreads between the depths ranged 75- 286 m and mostly caught at depths ranged 100-150 m (Figure 3).

Size And Fishing Ground Of ………….…… Operated In Indian Ocean (Widodo, A.A. et al.)

Figure 2. Position of wahoo caught by tuna long line during onboard observer program (2005-2010) which also describes the potential of horizontal distribution of Wahoo.

Figure 3. Depth range that caught by tuna long line during onboard observer program (2005-2010) which also describes the potential of vertical distribution of Wahoo. Wahoo is a pelagic, highly migratory species of the family scombridae which broadly distributed throughout tropical and subtropical oceans (Collette and Nauen 1983; Garberetal. 2005; Mc Bride et al., 2008). Little information is available on wahoo movement, although their availability change seasonally and the average size different in the various latitude. Wahoo may also migrate seasonally away from the equator following oceanic temperature patterns (Iverson & Yoshida, 1957).

Previous study by Nakano et al. (1997) noted that the catch rate of wahoo in the long line fishery varies at different depth and further argued that wahoo was surface oriented i.e. < 160 meters depth. It is reinforced by evidence the most of wahoo caught by long lines predominantly in the surface (Nakano et al. 1997; Beverly et al., 2009). Sepulveda et al. (2011) noted that depths layer of wahoo is up to 253 m, but in this study recorded that the maximum depth layer of wahoo recorded up to 285.7 m. NMFS (2001) noted

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that the distribution of wahoo is associate with warm, productive oceanic fronts, especially when these fronts are near coastal shelves and banks. Hook Rate From 85 tuna long line fishing trips, only 42 fishing trips those caught wahoo with total number of catch of wahoo was 463 fishes Hook rate ranged 0.9471.399 per 1.000 hooks/setting (Table1, Figure 4). The hook rate is higher compared to the hook rate of wahoo on the tuna long line operated in Pacific Ocean as reported by Kim et al. (2007) that the hook rate on the tuna long line operated in Pacific Ocean was 0.446 per 1.000 hooks. The other previous research noted that only 12 wahoo were caught during 5,500 hours of surface trolling in the open sea, more than 60 miles from coastal (Murphy & Ikehara 1955: 14). This species is known to travel solitarily or in small schools of two to twenty fish (Iverson and Yoshida 1957), and is attracted to banks, pinnacles and islands, as well as flotsam drifting in the open ocean (NMFS 2001). That condition allegedly as one of the reasons the hook rate of wahoo on the tuna long line was very low.

Fish Size The data of size (fork length-FL) of wahoo caught tuna long line tabulated by year in Table 2. In 2006, the size ranged 72-180 cm, in 2007 ranged 65-145 cm, in 2008 ranged 71-163, in 2009 ranged 70-156cm and in 2010 ranged 109-140 cm. The overall (unsexed) shows that the modus of the size of wahoo was 101110 cm as delineated on Figure 5. Table 2. Size of wahoo caught tuna long line based in Benoa during year 2006-2010. Fork length (cm) Min Max

Years

Number of sample (fish)

2006

21

72

180

2007

17

65

145

2008

33

71

163

2009

48

70

156

2010

18

109

140

Table 1. Hook rate of wahoo on the tuna long line year 2006-2010 based on onboard observer program.

Year

Number of Hooks

Catch of Wahoo (Fish)

Hook Rate (Fish/1000 hooks)

2005

14145

15

1.060

2006

25854

25

0.966

2007

121877

122

1.001

2008

150746

211

1.399

2009

72823

69

0.947

2010

20769

21

1.011

Figure 5. Size distribution of wahoo caught tuna long line based at Benoa in 2006-2010. Sommer et al. (1996) noted that maximum total length (TL) of wahoo was 250 cm (unsexed), length at first maturity Lm ranged 85-105 cm and the modus at 99.3 cm and according to Collette (1995) the common fork length was 170 cm (unsxed). Refer to this fact, the wahoo caught by tuna long line in Indian Ocean based in Benoa mostly were adult fish. This evidence is also ind icates the tuna long line was selective fishing gear for wahoo.

Figure 4.

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Hook rates fluktuation of wahooonthe tunalong line fisheries based at Benoa in 2006-2010.

Size And Fishing Ground Of ………….…… Operated In Indian Ocean (Widodo, A.A. et al.)

CONCLUSION From above description can be concluded as follows, the wahoo caught by tuna long line based at Benoa was between 1o31’ S -33o 40’S and 77o18’E 117o53’E and spreads between the depth of 75.2285.7 m. The hook rate ranged 0.947-1.399 per 1000 hooks/setting and mostly were adult fish.

Garber A.F.,Tringali M.D., & Franks J.S., 2005. Population genetic and phylogeographic structure of wahoo, Acanthocybium solandri, from the western central Atlantic and central Paciûc Oceans. Mar Biol. 147: 205–214.

ACKNOWLEDGMENTS

Gillett, R. 2011. Bycatch in small-scale tuna fisheries. A global study. FAO Fisheries And Aquaculture Technical Paper No.560. Food And Agriculture Organization Of The United Nations, Rome. 116 p.

We express our thank to observers of Research Institute for Tuna Fishery Benoa Mr. Abram Barat, Mr. Dian Novianto, Mr.Andi Bachtiar, Mr.Gamadi, Mr.Yusuf Affandi, Mr. I Nyoman S., Mr. Irwan Jatmiko as well as Mr. I Gede Sanjaya who provided the data. We also thank to Director of RCMFC Purwanto, PhD for valuable inputs and comments.

Collette, B.B. 1995 Scombridae. Atunes, bacoretas, bonitos, caballas, estorninos, melva, etc. In W. Fischer, F. Krupp, W. Schneider, C. Sommer, K.E. Carpenter and V. Niem (eds.) Guia FAO para Identification de Especies para lo Fines de la Pesca. Pacifico Centro-Oriental. 3 Vols. FAO, Rome. p. 1521-1543.

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Sepulveda C.A., Scott A. Aalbers, Soûa Ortega Garcia, Nicholas C.Wegner & Diego Bernal. 2011. Depth distribution and temperature preferences of wahoo (Acanthocybium solandri) off Baja California Sur, Mexico. Mar Biol. 158:917–926.

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