Relative abundance and biological characteristics of shrimp, Heterocarpus ensifer (Caridea: Pandalidae), catch on external margin of the continental shelf and slope, off northeast Brazil

Abstract

Heterocarpus ensifer belongs to the family Pandalidae Haworth, 1825, which includes species commonly inhabiting deep waters, thus explaining the relatively scanty information available on its biology. The specimens examined in the present work were collected by the Research Vessel "Natureza" belonging to Centro de Pesquisa e Gestão de Recursos Pesqueiros do Litoral Nordeste. The surveys were done from October 14 to November 21, 2000, along the external margin of the continental shelf and slope off northeastern Brazil, using bottom traps as fishing gear. The average length of the carapace and average weight of females and males were 23 mm and 5.6 g and 22.4 mm and 4.8 g, respectively. Females showed significant differences (P=0.001) in carapace length in relation to males, as well as in weight (P=0.004). The average length of the carapace between males and females did not exhibit significant differences (P=0.22 and P=0.24, respectively) in shallow waters (50-300 m), while in deeper waters (300 and 600 m) this difference was significant (P=0.001). The distribution of the fishing effort, as well as the relative abundance of the species by depth did not show significant differences (P=0.93 and P=0.20, respectively). H. ensifer seems to adapt well to different environments, being distributed over a wide range of depths, from 100 to 600 m, exhibiting a trend of greater abundance between 300 and 400 m.