Diet and reproduction of the goliath grouper, Epinephelus itajara (Actinopterygii: Perciformes: Serranidae), in eastern Brazil

Abstract

Background. The goliath grouper, Epinephelus itajara (Lichtenstein, 1822), is the largest Atlantic grouper. It has been the first marine fish subjected to a fishing moratorium in Brazil (since 2002). The aim of this study was to investigate basic biological aspects, particularly the diet and reproduction of this endangered species. We believe that our results, together with information already available in the literature, may be a foundation for new management and conservation strategies for this grouper in Brazil. Materials and methods. Specimens were obtained from an artisanal fish landings collaborative monitoring program in the cities of Caravelas and Alcobaça, Abrolhos Bank, eastern Brazil. Because of the fishing moratorium, we relied on sporadic incidental captures from fishermen or donation from the law enforcement agencies. Diet and reproduction of the goliath grouper was evaluated based on 34 specimens obtained between May 2005 and September 2010. Results. Body size of 32 females ranged from 27.4 to 150.0 cm total length (TL) (mean 87.4 ± SD 34.8), while size of 2 males were 97.0 and 115.0 cm TL. Of these, 16 specimens (47%) were juveniles. Sex ratio was estimated as 1 : 16 (males to females). Two developing females were recorded, one obtained in February 2006 and another in January 2007. The length of first maturation (L50) for females was estimated at 105.64 cm and the length where 100% of individuals are mature (L100) at 126.0 cm TL. A total of 34 stomachs were analyzed, six of them were empty. Teleosts and decapods dominated the diet. The major food items of mangrove-associated fish were decapods Callinectes sp., while the coral reef-associated fish ingested mainly the boxfish Acanthostracion sp. The most important item for juveniles was Callinectes sp., while Acanthostracion sp. was the most important item for adults. Conclusion. We suggest that the goliath grouper moratorium in Brazil should be maintained for a relatively long time frame—more than four decades.