Which shrimp are we catching? Cryptic species in the North Brazil Shelf

Shrimps of genus Penaeus are among the main exploited resources in the North Brazil Shelf Large Marine Ecosystem. Despite their economic importance, there is still a lack of consensus regarding their taxonomy and species distribution. The inability to identify commercially important species has a direct impact on both fishery management and ecosystems conservation, causing difficulties in monitoring and stock evaluations. This study aims to compare different barcoding sequences of commercially fished shrimps collected from three countries on the North Brazil Shelf Large Marine Ecosystem. Although the sampled individuals were expected to be a mix of the well-known commercial Penaeus subtilis and the cryptic species Penaeus isabelae, only P. isabelae was present in the catches. The exclusive presence of P. isabelae in the catches may indicate the complete absence of P. subtilis, or it could reflect the rarefaction of this species in the area which could be due to isolation mechanisms acting as barriers to larval dispersal around the Amazon area. Our results suggest that the distribution range of the two species needs to be re-evaluated and the use of a precautionary approach should to be applied on the management of brown shrimp resources since the biology and demographic parameters of the two cryptic species can differ and impact stock assessment results.