Collecting information on the pelagic phase of marine turtles from at-sea observations: The case of purse seine fisheries in the Indian Ocean

Type Proceedings paper
Date 2019
Language English
Other localization https://wwe.iotc.org/sites/default/files/documents/2019/12/IOTC-2019-WPDCS15-20_Rev1.pdf
Author(s) Chassot Emmanuel1, Sabarros Philippe2, Maufroy A3, Ruiz J4, Ramos Ml5, Barreau E1, Barde Julien2
Affiliation(s) 1 : Seychelles Fishing Authority, Victoria, Mahe, Seychelles
2 : Institut de Recherche pour le Développement, UMR MARBEC, Ob7, Sète, Occitanie, France
3 : ORTHONGEL, Concarneau, Bretagne, France
4 : AZTI-Tecnalia, San Sebastian, Basque country, Spain
5 : Instituto Español de Oceanografía, Tenerife, Canary Islands, Spain
Meeting WPDCS 2019 - 15th Working Party on Data Collection and Statistics. 27-30/11/2019, Karachi, Pakistan
Source WPDCS 2019 - 15th Working Party on Data Collection and Statistics. 27-30/11/2019, Karachi, Pakistan. 2019. IOTC-2019-WPDCS15-20_Rev1, 14pp.
Abstract

Observations of turtles in the open-ocean are essential to complement the information collected at nesting sites and rookeries, especially during the ‘lost years’ of their surface-pelagic juvenile phase. We used a large dataset of observations at sea collected onboard Seychelles, Spanish and French purse seiners over the period 2003-2019 to describe the occurrence of five species of turtles in the Western Indian Ocean: green ( Chelonia mydas ), loggerhead ( Caretta caretta ), leatherback ( Dermochelys coriacea ), Olive ridley ( Lepidochelys olivacea ) and hawksbill ( Eretmochelys imbricata ). A total of 895 turtles were recorded by human observers, 487 turtles after having been caught in the purse seine and hauled onboard the vessels and 408 turtles swimming around or lying on floating objects. An additional 86 turtles were recorded from images collected by cameras deployed on some purse seiners but could not be identified at the species level. Information collected on the status of turtles indicates that the very large majority (>90%) hauled on deck were released alive. Size data show that most turtles observed in the open ocean were juveniles and that the ones caught in association with free swimming schools of tuna were smaller than the ones caught in schools associated with drifting floating objects, these latter representing the majority of the observations. Through the turtles’ example, we aim to describe the availability of metadata and data standards widely used to share species occurrence data and key to foster collaborative science in the Indian Ocean and beyond.

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How to cite 

Chassot Emmanuel, Sabarros Philippe, Maufroy A, Ruiz J, Ramos Ml, Barreau E, Barde Julien (2019). Collecting information on the pelagic phase of marine turtles from at-sea observations: The case of purse seine fisheries in the Indian Ocean. WPDCS 2019 - 15th Working Party on Data Collection and Statistics. 27-30/11/2019, Karachi, Pakistan. 2019. IOTC-2019-WPDCS15-20_Rev1, 14pp. https://archimer.ifremer.fr/doc/00599/71131/