Abstract
Monitoring oceanic sharks bycaught by tuna purse seiners is of major importance for an appropriate assessment and management of these sensitive species. Electronic monitoring system (EMS) offers an opportunity to complement onboard observation for shark’s species monitoring, provided that cameras are well configurated to count and identify individuals on the deck. This study is evaluating the sharks’ observation gain of new cameras placed at strategic places (Funnel, Platform, Crow’s nest 2) onboard 4 equipped vessels with 3 different configurations. Six mixed trips were performed and EM shark’s data were compared to on board observation to evaluate camera performance and their benefit to the initial EMS configuration (Desk camera, Crow’s nest 1). Results shows that each additional camera increases shark’s observation compared the Desk camera. The Funnel camera was found the best camera in terms of counting and identifying the individuals at species level for all vessel configurations. The Crow’s nest 2 significantly increase observation of sharks on deck but is not able to identify species due to the distance. The Platform camera efficiency varies with vessel configuration and seems less powerful in terms of shark observation as it is located on the port side of the vessel where less sharks are released. The final analysis shows that one ideal option for optimizing sharks counting and identification on the upper deck would be to add both Crow’s nest 2 and Funnel cameras to the Desk camera with a higher resolution.