Back from the dead? Not really. The tale of the Galapagos shark (Carcharhinus galapagensis) in a remote Brazilian archipelago

Abstract

The Galapagos shark, Carcharhinus galapagensis (Snodgrass & Heller, 1905) is a large circumtropical species mostly found around oceanic islands. In Brazil, commercial fishing in the Saint Peter and Saint Paul Archipelago (SPSPA), located in the equatorial Mid-Atlantic Ridge, resulted in a drastic reduction in the number of carcharhinid sharks, and the once very abundant Galapagos shark was then considered locally extinct. In opposition to this premature conclusion, however, this study provides records of the species, as well as its abundance trends and patterns of distribution in the SPSPA from the period of supposed disappearance to nowadays. Results are based on fishermen interviews, video footage and catch data obtained during the shark monitoring program conducted in the archipelago from 2010 to 2019. Galapagos shark was the second most caught shark in SPSPA, showing that this species is not only still present but is also becoming again one of the most common shark species in the archipelago. No significant difference was observed in sex ratio and in the size frequency distribution of males and females. An apparent recovery of carcharhinid sharks was attested by all fishermen interviewed. This recovery was mainly noticed after the complete ban on elasmobranch fishing, in 2012, emphasizing the vulnerability of these species to fishing pressure. Further research on the biology, ecology, behavior, and distribution patterns of Galapagos sharks will greatly aid future decision-making regarding the management and conservation of the species, not only in SPSPA, but in all insular ecosystems.