REP. INT. WHAL. COMMN. 48, 1998

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SC/49/O 3

A Winter Cetacean Survey off Southern Morocco, With a Special Emphasis on Right Whales Giuseppe Notarbartolo-di-Sciara1, Elena Politi1, Abdellatif Bayed2, Pierre-Christian Beaubrun2 and Amy Knowlton3

ABSTRACT Between 20 January and 14 February 1996, a 20 m auxiliary ketch investigated the coastal waters of Southern Morocco, a former wintering ground for right whales (Eubalaena glacialis). The aims were to: verify if right whales could still be found in the area; evaluate the environmental conditions of the region and assess its suitability as a right whale habitat; investigate the status of other cetaceans living in the area; and establish a long-term cetacean sighting and stranding reporting mechanism in co-operation with the local authorities. A 750km survey yielded no cetacean sightings except inside Dakhla Bay, where communities of bottlenose dolphins (Tursiops truncatus) and Atlantic humpbacked dolphins (Sousa teuszii) were found to coexist. Local knowledge of a regular, predictable presence of large whales in the coastal zone was lacking. The hypothesis that the area still serves as a winter concentration site for the remnants of an eastern North Atlantic right whale population, although not falsified by this study, seems rather unlikely. The dearth of cetaceans in the shelf waters of Southern Morocco, as well as the possible over-exploitation of the fishing resources in the region, may be cause for concern and warrants further investigation. Finally, with the objective of increasing baseline information on the local cetacean fauna, and particularly concerning the possibility that right whales may be sighted in the future, a procedure was established for the long-term routine reporting of cetacean sightings and strandings by the Royal Navy of Morocco to the Groupe d’Etudes des Cétacés et Pinnipèdes du Maroc, Rabat.

KEYWORDS: RIGHT WHALES; BOTTLENOSE DOLPHINS; ATLANTIC HUMP-BACKED DOLPHINS; AFRICA; SURVEY-VESSEL.

INTRODUCTION The northern right whale (Eubalaena glacialis) is one of the four cetacean species considered critically endangered by IUCN's Action Plan for the conservation of whales, dolphins, and porpoises (Reeves and Leatherwood, 1994). In particular there are few data on the continued existence of right whales in the eastern North Atlantic. Recent sightings in the eastern portion of the North Atlantic and Mediterranean are quite rare (Aguilar, 1981; Evans, 1992), and include the sighting of an individual off southwestern Sardinia, Italy in May 1991 (Rossi, 1996), the observation of a breaching whale near La Coruña, Spain, on 5 Dec. 1993 (Arcos and Mosquera, 1993), another breaching whale off Tenerife, Canary Islands in Feb. 1995 (Erika Urquiola Pascual, Viceconsejerìa de Medio Ambiente, Tenerife, pers. comm.), and a cow and calf pair off SW Portugal on 3 Feb. 1995 (Martin and Walker, 1997). Studies of the whalers’ logbooks (Reeves and Mitchell, 1990) revealed that the Cintra Bay region, a coastal zone of north-western Africa encompassing an area between 22°-24°N along the coast of Rio de Oro (ex-Western Sahara, today part of Morocco), almost certainly represented a past wintering ground for the right whales of the eastern North Atlantic. Right whales were observed by whalers between November and April, with a possible peak in sightings in 1

Tethys Research Institute, viale G.B. Gadio 2, 20121 Milano, Italy. Groupe d’Etudes des Cétacés et Pinnipèdes du Maroc, Universite' Mohammed V, Institut Scientifique, 10106 Agdal – Rabat, Morocco. 3 New England Aquarium, Central Warf, Boston, Massachusetts 021103309, U.S.A. 2

January-February (Reeves and Mitchell, 1986). Although up to now, no vessel surveys have been conducted in this area for political reasons, on 31 January 1992 a single aerial survey was made from Nouadhibou (Mauritania) to Dakhla at about 0.8-1 km from the coast (Lamarche and Vely, 1992), but no cetaceans were seen. Recent inventories of marine mammals from the northeastern Atlantic (Duguy and Aloncle, 1974), and in particular from Morocco (Bayed and Beaubrun, 1987) did not include right whales. Recent political changes meant that the organisation of a full research programme in the area became possible. In order to investigate the status and even evidence of an eastern North Atlantic population of right whales, it seemed wise to investigate the most likely breeding area, and to discover whether there was any local knowledge of the seasonal presence of whales along that coast (Reeves and Leatherwood, 1994). This provided the impetus for the planning of a field expedition to the coastal area of Southern Morocco, in January and February 1996. The expedition was funded by the UK-based Whale and Dolphin Conservation Society (WDCS), and organised by the Tethys Research Institute in co-operation with the Groupe d’Etudes des Cétacés et Pinnipèdes du Maroc, GECPM (affiliated with the Zoology and Animal Ecology Department, Institut Scientifique of

NOTARBARTOLO-DI-SCIARA et al.: SURVEY OFF SOUTHERN MOROCCO 548 the Mohammed V University, Rabat) and the New England During the first part of the cruise (21 January to 2 February) the Aquarium, Boston, USA. weather allowed us to perform surveys, although these had to be interrupted several times due to temporary increases in wind speed. On the second part of the cruise a spell of bad weather reaching MATERIALS AND METHODS gale force from the north northeast, lasting without interruption for The vessel used was Tethys’ 20 m-long, steel-hulled auxiliary ketch 12 days. During this period the harbour authorities advised against Gemini Lab. The vessel arrived in Dakhla on 14 January 1996, and leaving the moorings, therefore preventing field research from 3 to operated from 20 January to 14 February. Departure from 14 February. Weather conditions allowed surveying on only nine Morocco back to Tenerife was on 14 February. days (23-24 January, 26-30 January, 1-2 February), giving a total distance surveyed of 404.8 n.miles (750 km). The overall survey Study area track is shown in Fig. 1. Based on XIX Century whaling records (Reeves and Mitchell, 1990), the boundaries of the study area were chosen between 24°N Interviews and 22°N, from Dakhla (ex-Villa Cisneros) south to Cape Barbas, We took the opportunity to interview local fishermen, officials and along a stretch of approximately 20 n.miles from the coastline. others for information on cetaceans in the region. The coast in the region consists of steep limestone cliffs, up to 70m high, alternating with vast sandy beaches. Except for Dakhla Bay, the coast offers no shelter from westerly winds. Cintra Bay and to a much lesser extent the smaller Gorrei Bay to the south, provide moderate temporary shelter from the offshore northwest swell, which produces an almost uninterrupted breaker zone along the coast. Entrances to both Dakhla and Cintra Bays are closed off by a complex system of sandbars, with narrow passes (unmarked in Cintra Bay) barely deeper than the 2.6m draft of the research vessel; these were not negotiable with poor light conditions or with high swell. Dakhla Bay is a small inland sea, 25 n.miles long and 5-7 23° 30’ n.miles wide, closed off from the ocean by the elongated Rio de N Oro Peninsula. Most of its extent, particularly in its southern portion, is shallower than 2m; however, in the northern section a large area is navigable and could be surveyed. The shelf is very wide on this portion of the African continent, with the 200m depth contour line located at about 65km from Cape Barbas, and extending farther northwards to over 110km off Dakhla. The sea bottom is sandy and the water turbidity high, both in Cintra and Dakhla Bays (Secchi disc readings: 4m) and offshore. Waters 23° along this coast are part of the productive Canary Current System, 00’ with major upwelling zones occurring just off the continental shelf. N Accordingly, the area is considered one of the world’s richest 30 km 0 fishing grounds. Dakhla (population: 35,000) is the only urban centre in the area, with a hospital, a major naval base and an airport. Small fishing settlements consisting of rudimentary shacks are 16° 20’ W 16° 00’ W 15° 40’ W scattered along the coast of the study area, the largest of which was found at Puntillas de las Raimas, at the northern end of Cintra Bay. Fig. 1 - The study area with the complete on-effort survey track.

Survey methodology Surveys were conducted at an average speed of 5 kts (9.4 km h-1). Survey activities were recorded in real time using Logger 4.1, a dedicated software system developed by IFAW, interfaced with the vessel’s GPS. Surveys were conducted when wind speed did not exceed Beaufort 3. Search sessions were carried out by naked eye by a minimum of two trained observers, rotating every hour, placed at 3.5m above sea level, visually covering 180° on either side of the boat. While on effort, environmental variables, such as sea state, visibility, wind speed and direction, sea temperature and presence or absence of fishing boats, were recorded at regular intervals. In addition, six plankton tows and two Secchi disc measurements were also made. Under normal conditions, the weather in the Dakhla region is dominated by the northeast trade winds, which are at their lowest intensity in January. By contrast, very strong winds were experienced during this expedition, during what was locally considered as one of this century’s most severe winters in Morocco.

RESULTS During the survey in open ocean waters between Dakhla and Cintra Bay, as well as during the off-effort navigation on the following night, the research vessel was surrounded by many large fishing ships. Vessels could be seen in every direction for the entire period, and the radar confirmed the presence of other ships beyond the horizon, throughout its 15km range. No pleasure craft were encountered. Surprisingly, no cetaceans were sighted in the waters outside Dakhla Bay, in spite of the excellent weather conditions encountered, e.g., on 26 and 27 Jan. Large numbers of sea birds were seen (particularly Sula bassana, Larus fuscus, Sterna spp., and Stercorarius sp.), which attested, together with the large quantity of fishing vessels encountered, the remarkable secondary productivity of these waters. It was thus surprising that, as in a recent aerial survey (Lamarche and Vely, 1992), no cetaceans were seen. High-seas fishermen interviewed by us in Dakhla

REP. INT. WHAL. COMMN. 48, 1998

stated that they often saw dolphins, but always near to the continental slope4. However two dolphin species, bottlenose dolphins (Tursiops truncatus) and Atlantic hump-backed dolphins (Sousa teuszii) were observed ten times within Dakhla Bay (Tab. 1, Fig. 2). Bottlenose dolphins ranked highest in relative abundance. The presence of Atalntic hump-backed dolphins in these waters - the northernmost location of the species’ range - had been reported before by Beaubrun (1990). The bottlenose dolphins appeared to be large, possibly exceeding 3.5m in length, with a greyish coloration typical of northeast Atlantic specimens. They were found both in the southern part of the bay and in the eastern portion of the northern part. In most instances, these dolphins avidly engaged in bowriding in front of the research vessel, and showed remarkable confidence with boats and humans. Based on a preliminary analysis, 21 different individuals could be identified from the photographs, six of which were seen on two different sightings, suggesting that the Dakhla Bay bottlenose dolphin community is rather small. Unlike bottlenose dolphins, hump-backed dolphins appeared to be confined to the shallows of the northern end of the bay, and were wary of our presence. They never came near the bow of Gemini Lab, and it was difficult to approach them enough to get satisfactory photographs. Mixed groups of bottlenose and humpbacked dolphins were not observed. During our stay we examined four stranded cetacean carcasses: two bottlenose dolphins, one hump-backed dolphin, and a 4m long newborn female Bryde’s whale (Balaenoptera edeni). The last stranded just north of Dakhla on 14 January and was positively identified prior to total decomposition. One of the two dead bottlenose dolphins, a young specimen, bore on its body clear marks of line entanglement. The Atlantic humpbacked dolphin, also a juvenile, was found entangled in an octopus line at the northern end of Dakhla Bay. We also inspected parts of skeletons privately collected in Dakhla: one belonged to a fin whale (Balaenoptera physalus) found stranded in Cintra Bay in recent years, and presumably the same beached carcass which had been spotted during an aerial survey for monk seals (A. Aguilar, pers. comm.). More ancient skeletal parts of yet another balaenopterid whale, species and origin unknown (but most likely a humpback, sei or Bryde’s whale, based on analysis of photos of the lower jawbone and articulation), were also found. Table 1 Summary of cetacean sightings. n = number of sightings, X = mean group size, s = standard deviation. Cetacean species sighted

n

X

s

bottlenose dolphin, Tursiops truncatus

6

6.8

4.7

Atlantic hump-backed dolphin, Sousa teuszii

4

6.9

3.1

4 On 14 Jan. 1996, just outside the continental slope, on her way to Southern Morocco from Tenerife, Gemini Lab encountered a school of 10 striped dolphins, Stenella coeruleoalba (25°58’N, 015°54’W), and a school of 14 short-finned pilot whales Globicephala macrorhynchus (25°35’N, 015°57’W).

549

23° 50’ N

0

16° 16°00’ 00’W W

10 km

23° 40’ N

15° 50’ W

Fig. 2 - Locations of dolphin sightings within Dakhla Bay. Sightings of bottlenose dolphins are marked with crosses, sightings of Atlantic hump-backed dolphins with black squares.

Contacts at the local level provided useful information about local knowledge of the presence of cetaceans in the study area, and helped to establish reporting schemes for future cetacean sightings. Little knowledge on large whales seemed to exist locally. Fishermen interviewed in Cintra Bay stated unanimously that, in their memory, no large whale had ever been seen frequenting the bay’s waters. Some did say, however, that whales were seen at times ‘40-50 n.miles offshore’. The stranding of a neonate Bryde’s whale in Dakhla Bay was considered exceptional (Col. H. Ferhi, pers. comm.). Fishermen in Dakhla Bay were obviously aware of the presence of dolphins, and also reported the occasional sighting of killer whales, Orcinus orca, a species known to occur in the region (Hammond and Lockyer, 1988; Reeves and Mitchell, 1988). The sighting of a pod of three killer whales just off the Dakhla pier in summer 1995 was also reported to us by the Royal Navy. As a result of contacts which had been made possible during the expedition, an agreement was reached between the Royal Navy and the GECPM for the routine reporting of cetaceans sighted by the Navy during regular surface and air patrolling activities. GECPM sighting forms were distributed to the officers in charge of the patrols, along with photographs and drawings of right whales in dorsal and lateral views to assist in correct species identification.

DISCUSSION Right whales Weather conditions reduced survey effort considerably in the portions of the study area that could have been suitable to right whales, so no firm conclusions concerning the presence or absence of this whale species in the area could be reached based solely on our sighting data. However, the complete lack of knowledge by the local fishermen of the existence of large whales in this coastal region strongly suggests that it is unlikely that a remnant eastern North Atlantic population of right whales still frequents the Cintra Bay Grounds. Other cetaceans The survey highlighted a surprising absence of cetaceans in the productive coastal waters of Southern Morocco. This requires

NOTARBARTOLO-DI-SCIARA et al.: SURVEY OFF SOUTHERN MOROCCO 550 more detailed investigation. For example, one could hypothesise a the organisation of detailed studies of the odontocete communities link between such observation and the fishery-related mass found in Dakhla Bay. mortality of dolphins, which occurred off Mauritania a few months For (1) all the contacts and the necessary agreements have been earlier, in November 1995 (Aguilar, 1996). However, the presence made during the expedition. The main reporting authority will be within Dakhla Bay of two dolphin species (Tursiops truncatus and the Royal Navy, while the recipient of the reports will be the Sousa teuszii) suggests that it might provide a fruitful study area and GECPM in Rabat. Special emphasis was given to the reporting of yield first-hand information on sighting frequencies, distribution, possible right whale sightings and strandings, and appropriate habitat use, social behaviour and causes of mortality for these documentation has been distributed to the patrolling officers to species. make sure that right whale sightings do not go unnoticed nor unrecognised. Fishing activity and implications for cetaceans We observed a high intensity of large-scale fishing effort over the ACKNOWLEDGEMENTS continental shelf of Southern Morocco. Fishing, the main activity The research was funded by the Whale & Dolphin Conservation in the region, consists mostly of large-scale offshore and artisanal Society. Randall R. Reeves, Peter J.H. Evans and two anonymous coastal fisheries. Among the former, most of the large ocean-going referees reviewed the manuscript, and provided useful and vessels involved are foreign (Spanish, Korean, Chinese and constructive comments and improvements. We wish to thank the Russian), although Morocco is increasing its own fishing potential. Royal Navy of Morocco, and particularly Col. C.F. Hassan Ferhi, Fishing by such vessels takes place throughout the shelf width, all Commander of the 3rd Naval Base in Dakhla, for his availability, along the coast and mainly consists of bottom trawling for demersal interest, and continued support during our stay in Dakhla. We are fish and cephalopods. Unofficially, Spanish fishing officers in also grateful to Mr. H. Ahmed, chief of the Port Police of Dakhla, Dakhla expressed their view that fishing resources in the area were who strove to make us feel welcome in Southern Morocco. We unquestionably severely over-exploited. Artisanal, small-scale gratefully acknowledge the vessel’s crew, G. Barbaccia (skipper), coastal fishing activities are practised by local fishermen based C. Almirante, I. Cavarretta, and S. Canese, and colleagues H. mainly in Dakhla and Cintra Bay, although several minor Bazaïri (GECPM), A. Gatti, L. Medlund and G. McCallum who settlements can be found scattered along the coast. These also participated in the cruise. fishermens’ boats are of simple, wooden construction, 4-6m long, We also would like to thank R.R. Reeves, S. Kraus, S. Mayo, powered by 5-20HP outboard engines. Target species include A. Smith and A. Aguilar for their valuable advice during the octopus, squid, crustaceans, and a large variety of demersal fish. organisation of the expedition. Finally, we would like to gratefully The gear used includes “poulpiers” (lines up to 30m long acknowledge the International Fund for Animal Welfare (IFAW) connecting empty jars, used to catch octopus between November for making the Logger software available to us. and February which are forbidden in Dakhla Bay), the normally G.P. Donovan and two anonymous reviewers provided forbidden bottom-set gillnets (used nonetheless throughout the valuable advice on the manuscript. year), and fishing lines. These high levels of fishing activity may hinder or already have hindered attempts by right whales to reREFERENCES colonise the area. The potential for interactions between the two dolphin species Administration des Eaux et Forêts et de la Conservation des Sols. 1995. Plan Directeur d’Aménagement et de Gestion des Aires Protegées and fishing activities in Dakhla Bay requires further investigation. Project n°15 EF/CPN/PN/92 - MA;VA/AEFCS. [In French]. 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