Update on post-release survival of tagged whale shark encircled by tuna purse-seiner
In the tropical eastern Atlantic Ocean, whale sharks are sometimes encircled by nets of tropical tuna purse-seiners. In order to estimate the post-release survival of encircled individuals, a post release survival experiment, using pop-up satellite tags, was conducted in this ocean in 2014. This study presents updated results from this experiment. In addition to the six (five included in the study and an individual from Murua et al. 2014) whale sharks tagged in June–July 2014, five other individuals were tagged in June 2016. Among these 11 tags, seven individuals survived at least 21 days after release, three tags detached after 3 and 7 days and the fate of these individuals remains unknown, and one tag failed to report. Although the sample size remains limited, the results indicate a post release mortality rate following encirclement of large whale shark of 0%. Nevertheless, there remains an urgent need to increase post-release tagging experiments of whale shark encircled by purse-seine nets to estimate the survival rate and to define, if needed, regulatory measures to protect this shark species.