Spawning aggregation sites of the cubera snapper, Lutjanus cyanopterus, on the continental shelf of Bahia state, Northeastern Brazil

Abstract

The cubera snapper (caranha), Lutjanus cyanopterus, is an important resource for reef fisheries in Northeastern Brazil, currently classified as Vulnerable (VU) on the Red List of Threatened Species. This species forms large transient reproductive aggregations, concentrating their reproductive efforts in a short period of the year and in specific spawning sites, which have already been well documented in the Caribbean. These aggregations are predictable in time and space, making them considerably vulnerable to overfishing and other sources of anthropic impacts. These tend to reduce the population’s renewal capacity and genetic diversity, thus contributing to the decline of fish stocks and to the process of local extinctions. Between 2009 and 2010 we identified two L. cyanopterus aggregation sites, commonly known as “Caranheiros”, in two sub-areas located at the continental shelf-break zone of Bahia state, Northeastern Brazil, in the East Brazil Shelf Large Marine Ecosystem (LME16), between latitudes 12 °S and 15 °S. The present study aims to (1) describe patterns of spatial and temporal distribution, and the biological characteristics of L. cyanopterus’ catches from line fisheries targeting the specific aggregations in the two Caranheiros sites; and (2) validate the reproductive character of these aggregations through macroscopic evaluation of sexual maturity phases of the fishes caught. We analyzed fisheries and biological sampling data from the catches of artisanal fleets monitored in the two sub-areas between 2005 and 2014. The identified aggregations occur annually from December to May, with capture peaks concentrated in waning to waxing moon phases, in January, February and March. The predominance of mature, pre-spawning and spent (recent spawning) individuals, males and females, in these aggregations revealed the reproductive activity in both sites. Identifying and validating these spawning sites may contribute to the development of recovery and conservation plans for this threatened species. The continuous monitoring of fisheries on aggregations is a priority, aiming to trigger management responses and adaptative fisheries management. Considering these sites are highly vulnerable and have high local socioeconomical importance, especially to traditional fishers, the exact location of the analyzed “Caranheiros” is not revealed in this publication. However, it has been made available to the government agencies responsible for fisheries control and surveillance, as well as for implementing management and conservation measures for the sustainable use of fisheries resources.