Molecular identification and first demographic insights of sharks based on artisanal fisheries bycatch in the Pacific Coast of Colombia: implications for conservation

Abstract

The Pacific coast of Colombia is characterized by mangrove ecosystems which play a crucial role as possible nurseries for juvenile sharks. However, trophic food webs from coastal ecosystems are heavily disturbed by increased fishing pressure, which affects numerous shark species. In this region of the Eastern Tropical Pacific (ETP), fisheries’ data from coastal areas are scarce and unspecific, as most sharks from artisanal fisheries are landed decapitated and finless, making their morphological identification difficult. For the establishment and implementation of effective regional conservation and management policies, information on the diversity and population dynamics of shark species is crucial. We therefore sequenced the mitochondrial NADH2 gene of 696 samples taken from fishermen’s landings of shark’s bycatch along the Colombian north Pacific coast. We were able to identify 14 species of sharks, two of the most abundant species were Sphyrna lewini and Carcharhinus falciformis, both evaluated on IUCN the Red List of Threatened species (Critically Endangered and Vulnerable) and CITES regulated. We found low genetic diversity in the sampled area increasing the concern for both species in the region, even more considering that the majority of individuals were juveniles. Our results showed the importance of genetic markers for first population genetic insights as a complementary tool during the decision-making process in management plans. For this specific region, strategies such as the delimitation of conservation priority areas or the regulation of fishing gears could help improve the sustainability of shark populations in the Colombian Pacific.