OFFSHORE FISHERIES OF THE SOUTHWEST INDIAN OCEAN:

their status and the impact on vulnerable species

OCEANOGRAPHIC RESEARCH INSTITUTE Special Publication No. 10 Rudy van der Elst and Bernadine Everett (editors)

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OFFSHORE FISHERIES OF THE SOUTHWEST INDIAN OCEAN:

their status and the impact on vulnerable species Rudy van der Elst and Bernadine Everett (editors)

South African Association for Marine Biological Research Oceanographic Research Institute Special Publication No. 10 May 2015

Book title: Offshore fisheries of the Southwest Indian Ocean: their status and the impact on vulnerable species Editors: Rudy van der Elst and Bernadine Everett First published in Durban in 2015 by the Oceanographic Research Institute (ORI) and the Western Indian Ocean Marine Sciences Association (WIOMSA) Copyright © 2015 | ORI and WIOMSA ISBN: 978-0-620-64762-5 (digital); 978-0-620-64761-8 (print) Copyright notice: All rights of this publication are reserved to ORI, WIOMSA, the editors and the authors of individual chapters. Notwithstanding, this publication may be reproduced in whole or in part for educational or non-profit purposes without special permission from the copyright holders provided that acknowledgement of the source is made. No use of this publication may be made for resale or any other commercial purpose without permission in writing from the copyright holders. Disclaimer: the contents of this publication do not necessarily reflect the views of ORI, WIOMSA, Sida or the GEF. Furthermore, the geographic designations used in this publication do not imply any opinion as to the legal status or delineation of any territory referred to. Acknowledgement: This book is based on research by the Southwest Indian Ocean Fisheries Project (SWIOFP) and its publication has been made possible by the generous support of the Government of Sweden and the Global Environmental Facility (GEF) through the Western Indian Ocean Marine Science Association. Book citation: Van der Elst RP and Everett BI. 2015. (eds). Offshore fisheries of the Southwest Indian Ocean: their status and the impact on vulnerable species. Oceanographic Research Institute, Special Publication, 10. 448pp. Design: Desiré Pelser | Earth & Oceans Developments | Publications and Communications

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SEA TURTLES

Table of contents Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Introduction and objectives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Regional sea turtle biodiversity overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Species distribution, status and hotspots in the SWIO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Species overviews. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Loggerhead (Caretta caretta). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Olive ridley (Lepidochelys olivacea) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Green turtle (Chelonia mydas). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Hawksbill (Eretmochelys imbricata). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Leatherback (Dermochelys coriacea). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Regional genetic structure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Available information by country. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . South Africa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mozambique . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Tanzania – including Zanzibar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Kenya. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Madagascar. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Comoros. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Seychelles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mauritius . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . La Réunion/Mayotte/Eparses (France). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Somalia. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sea turtle status in the SWIO and the relative importance of fishery related mortality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Balancing threats, mitigation measures and their application to sea turtles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Regional conventions and commissions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Recommendations and identification of research priorities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Known sea turtle databases. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Literature cited . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Annex. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Previous page: Young green turtles, tagged and photo-identified, before release on Juan de Nova. Photo by Jérôme Bourjea.

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9. SEA TURTLES A review of status, distribution and interaction with fisheries in the Southwest Indian Ocean1 Jérôme Bourjea2

Abstract The bycatch of sea turtles is of growing concern for the management of many fisheries, from large scale pelagic fisheries to small scale artisanal and coastal fisheries. The Southwest Indian Ocean (SWIO) hosts important nesting and feeding grounds for sea turtles but evidence points to populations facing significant human threats, especially from fisheries. We review the global status of each of the five known sea turtle species in the western Indian Ocean: Chelonia mydas, Eretmochelys imbricata, Lepidochelys olivacea, Caretta caretta and Dermochelys coriacea. Information on their diversity, status and human-related threats in each of the nine SWIO countries is presented and analysed: South Africa, Mozambique Tanzania (including Zanzibar), Kenya, Madagascar, Comoros, Seychelles, Mauritius and La Réunion/ Mayotte/Eparses (France). Despite long-term monitoring programmes within this region (>30 years), data availability in the SWIO remains inadequate for thorough population assessment, partly attributable to the complex life history of these species. This chapter highlights as significant the impacts of three major fisheries in the SWIO: gillnetting, prawn/ shrimp trawling and longlining. However, it is important to view the impacts of fisheries in the light of land-based and other coastal threats. It is clear that, despite strong legislation prohibiting the direct take of turtles throughout the entire SWIO, fisheries are still regarded as the most important threat in this region. Several recommendations and research priorities are proposed in this chapter.

Introduction and objectives Sea turtles are highly vulnerable reptiles that have been subjected to direct exploitation for centuries, resulting in severely depleted populations in many cases. As the awareness of their plight and threatened status grew, so too has the advent of their protection in many regions, including the Southwest Indian Ocean (SWIO). Whilst this protection has been successful in many cases, the threat to sea turtles remains high because of inadequate compliance with regulations and especially mortality posed by fisheries. The region has over the past few decades seen a huge increase in fisheries diversification and effort, often resulting in higher turtle mortalities as a bycatch. The SWIOFP programme has as an overriding objective the development of fisheries in the region, especially offshore and industrial fisheries. Concurrently, such development is to take place in a sustainable manner in full recognition of an

ecosystem approach (EAF). This places a burden on future fisheries development with respect to mortalities induced on harmless and vulnerable animals such as sea turtles. In a comprehensive Gap Analysis for SWIOFP (van der Elst et al. 2010), it was concluded that all available information about sea turtles in the WIO should be collated and interpreted in a Retrospective Analysis. This would then serve as a baseline document to inform future fisheries development strategies in the WIO region in the light of an EAF approach. In particular it would contribute to management at a regional level. In view of the above, this chapter has been compiled to serve that purpose and provide a status of knowledge on sea turtles in the WIO, especially in the light of fisheries interactions. Moreover, this analysis highlights specific gaps and challenges.

1. Part of this report reflects (a) an updated analysis of the FAO workshop held in Zanzibar in 2006 to assess the relative importance of sea turtle mortality due to fisheries, (b) its subsequent publication in the 2008 WIO Journal of Marine Science (7 (2)) and (c) IOSEA MoU National Reports and database facilities. 2. Institut Français de Recherche pour l’Exploitation de la Mer (IFREMER), La Réunion, France; University of La Réunion – FRE CNRS. Email: [email protected]

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Even if locally sea turtle behaviour, feeding and reproduction are well understood, the lack of a global vision and understanding of their movement between the successive habitats and their interaction with regional fisheries does not lead to appropriated measures for conservation at the regional level. In support of this, SWIOFP developed, under its biodiversity component, an activity related to the study of the open sea movement of sea turtles in the WIO using a modelling approach based on telemetry and tagging. The final objective thus being to assess interaction between sea turtles and open sea fisheries within an ecosystem approach. A synopsis of most of the information on sea turtle threats can be accessed via the individual countries’ national reports’ online facility maintained by the IOSEA MoU (www.ioseaturtles.org). This Retrospective Analysis provides the most up to date assessment of sea turtle status at a regional level in the WIO, with a special focus on fisheries interactions.

Regional sea turtle biodiversity overview Species distribution, status and hotspots in the SWIO The Southwest Indian Ocean is known to host five species of sea turtle (Marquez 1990; Ratsimbazafy 2003; Seminoff 2004). Of these, the green turtle (Chelonia mydas) and hawksbill (Eretmochelys imbricata) are the most widely distributed and abundant in this region, with the green turtle being by far the most numerous. These two species have also been the most severely impacted by directed exploitation (Hughes, 1974a, b; Frazier, 1980, 1982). Loggerheads (Caretta caretta) and leatherbacks (Dermochelys coriacea) are most common in South African waters, but less common in the rest of the region, and have little importance in relation to commercial and directed exploitation (Hughes, 1974 a, b, Hughes 2010). Relatively little has been documented on the olive ridley (Lepidochelys olivacea) and this species is not considered to be much more that a vagrant to the region. Details per country and species are provided in Table 1.

Table 1: Nesting and sightings recorded per country (H>1,000 individuals per annum; M =100-1,000 ipa and L