Discovery of a potential open ocean nursery for the endangered shortfin mako shark in a global fishing hotspot

13 pages, 5 figures, 3 tables

Populations of large pelagic sharks are declining worldwide due to overfishing. Determining the overlap between shark populations and fishing activities is important to inform conservation measures. However, for many threatened sharks the whereabouts of particularly vulnerable life-history stages - such as pregnant females and juveniles - are poorly known. Here, we investigated the spatial distribution of size classes, energy transfer and reproductive states of pregnant females of the endangered shortfin mako, Isurus oxyrinchus, using spatially resolved catch data from a Spanish surface longline vessel (1996 - 2009) in the South-east Pacific Ocean. Our results suggest a general eastward gradient of occurrence of pregnant females of thousands of kilometers from western oceanic feeding grounds towards the eastern Pacific, where we observed an aggregation area of small juveniles. Moreover, the potential nursery likely overlapped a longline fishing hotspot, increasing the vulnerability of juveniles from fisheries. Our results suggest that limiting fishing pressure in this area could reduce mortality of early life stages and contribute to the conservation of this endangered shark species

This work was funded by Fundação para a Ciência e a Tecnologia (FCT) through PTDC/BMA/3536/2021 (to G. Mucientes and N. Queiroz) and CEECIND/02857/2018 (to N. Queiroz), and PTDC/ASP-PES/2503/2020 and CEECIND/CP1668/CT0007 (to M. Vedor). D.W. Sims received funding support from a European Research Council (ERC) Advanced Grant (883583 OCEAN DEOXYFISH) and a Marine Biological Association Senior Research Fellowship

Peer reviewed