Identifying nearshore nursery habitats for sharks in the Eastern Tropical Pacific from fisheries landings and interviews

Abstract

The Eastern Tropical Pacific (ETP) comprising the coasts of Costa Rica, Panama, Colombia and Ecuador, represents an area of high marine biodiversity that supports productive fisheries, and acts as an important migratory corridor for many marine species. Despite its biological importance, the ETP is understudied and lacks sufficient data for science-based fisheries management and conservation decision-making. The aim of this study is to consolidate understanding of the current and historical distribution of sharks and mobulid rays in the ETP. We used interviews of coastal community stakeholders to document traditional knowledge of shark and mobulid ray species and distributions. We also analysed small-scale fisheries landings data, where available, to quantify local exploitation patterns and the importance of sharks and rays in small-scale fisheries catches. All shark species landed in the dominant nearshore gillnet fishery show very low mean individuals weights (<5 kg), indicating that the fisheries are dominated by juveniles, captured . Aside from smooth-hounds (Mustelus spp.), the scalloped hammerhead shark, Sphyrna lewini, is the most frequently landed shark species in the region by weight and number, with peaks in abundance between April - July. From 132 interviews in 51 communities across the three countries, and landings data from two small-scale fisheries sites, we identified 41 sites in 12 broad geographical zones as important shark nursery habitats. Of these sites, 68% were associated closely with large mangrove systems of the ETP, highlighting the importance of this habitat for shark life history. No patterns were seen in the occurrence or distribution of mobulid rays in coastal areas. Marine protected areas and responsible fishing zones cover 37% of identified nursery habitats in the ETP, 30% in Costa Rica, 48% in Panama and 30% in Colombia. These findings provide an important indicator of conservation status of sharks in the ETP, and allow for prioritising and informing the work still to do.