Growth parameters of the Caribbean sharpnose shark, Rhizoprionodon porosus (Poey 1861), off Pernambuco State, Brazil

Abstract

The present paper aims to describe general growth parameters of the Caribbean sharpnose shark, Rhizoprionodon porosus (Poey, 1861), apllying a size frequency analysis through the von Bertalanffy growth equation, focusing possible correlation with the fishing operation off Pernambuco State coast. Catch composition comprises a high percentage of adults females and young males, suggesting that such population segregate by size, sex and reproductive stage, and that such fleet operation is restricted to coastal areas. The conducted analysis to verify the existing differences between growth rates of males and females showed to be significantly high, indicated that females grow bigger, but that males grow faster, that K=0.42, t₀=-1.10 year and L∞=87.13 cm for males; and K= 0.30, t₀=-1.12 year e L∞=106,82 cm for females, respectively are close if comparable to other species of Rhizoprionodon genus, and even if compared with other small and medium group size sharks. Females have higher increase in body weight, in relation to total length, as can be observed by the eviscerated weight and total lenght relationships. Given the increasing pressure on stocks of small coastal sharks off Pernambuco State and the importance to validate the parameters here verified, further information and studies are required to enable stock assessment and facilitate determination of levels of fishing effort.