Reef Fish in the Vitória-Trindade Seamount Chain of the Southwestern Atlantic: Biogeographical Corridors and Impact of Fishing

Abstract

This paper aimed to study the community structure of large reef fish off the central coast of Brazil by defining the spatial distribution patterns of 34 species in the outer shelf (50 to 100 m) between 13 and 22ºS, including sea banks, seamounts and the Trindade Island, seeking further to interpret these patterns in light of biogeographic knowledge. In addition, this study attempted to estimate the impact of fishing on the community in different regions using mean weight and size distribution data. The data were obtained in four exploratory fishing surveys of demersal resources employing a bottom longline with steel wire under the aegis of the REVIZEE Program between 1996 and 1998. The numerical abundances were standardised in catch-per-unit-effort (CPUE) in number, and species matrices per station were subjected to detrended correspondence analysis (DCA) and cluster analysis. Reef fauna in the southwestern Atlantic can be divided, in its continental margin, into a tropical component and a subtropical component from latitude 19ºS, which corresponds to the Southern limit of the Abrolhos Bank. North of 19ºS, four distribution patterns were identified (North, Abrolhos, Banks and Trindade). The similarity between the last three enabled the definition of an “Abrolhos-Trindade faunal complex”. Evidence of the impact of commercial fishing on the structure of reef communities was found through differences in the sizes of species studied, which may have occurred differently in each one of the regions of the Abrolhos-Trindade complex. The results also reinforce the importance of the need for conservation measures in these areas.