Population structure of nurse sharks, Ginglymostoma cirratum (Orectolobiformes), caught off Ceará State, Brazil, south-western Equatorial Atlantic.

Abstract

The nurse shark, Ginglymostoma cirratum, is considered an endangered species in Brazil and its capture by fisheries forbidden. Despite such legislation, nurse sharks continue to be caught as these laws are unenforced and fisheries are not monitored. The goal of the present study was to describe the population structure of nurse sharks caught off Ceara´ State, north-eastern Brazil, based on the following aspects: abundance and size, sex-ratio, fisheries incidence and seasonality of captures. Landings were monitored weekly during a two-year period. A total of 189 specimens were recorded. Total length (TL) varied between 73 and 274 cm. The male–female ratio did not differ significantly (1.19C:1F). TL of individuals landed as carcasses was estimated based on interdorsal length. The following equation was obtained for males and females: TL ¼ 12.606ID + 14.24 (R2 ¼ 0.9505). Most of the landed sharks were juveniles (86.2%). No seasonal pattern of abundance and TL variation wasobserved. Management of this fishery is required in order to prevent localized over-fishing of nurse sharks.