VIRTUAL POPULATION ANALYSIS OF THE CARIBBEAN SHARPNOSE SHARK, Rhizoprionodon porosus (POEY, 1861) (CARCHARHINIDAE), CAUGHT OFF PERNAMBUCO STATE, NORTHEASTERN BRAZIL

Abstract

We applied a steady-state Virtual Population Analysis–VPA to the stock of the Caribbean sharpnose shark, Rhizoprionodon porosus (Poey, 1861) (Carcharhinidae) population caught off Pernambuco State continental shelf, North-eastern Brazil. Through the computational program VIT – “Software for fi shery analysis”, we show that even short-data series (1 year of sampling) can produce a useful (diagnosis) of fi shery resources. The main objective of VIT program is to study the dynamics of a single species’ population subject to exploitation, the variations in the exploitation rate, the interaction among fi shing gears, and the reaction of the population to changes in the exploitation pattern, independently to the changes on catch and recruitment. The decision to conduct a VPA rely on the importance to observe the impact of fi shery in a non-target species, and the diffi culty to implement regulation and management measures on such a fi shing stock. The results showed that the female stock is submitted to high levels of fi shing mortality, but this is not true for the male stock; the current level of effort would drive the Caribbean sharpnose shark to a status of risk, denoting the susceptibility of this species to fi shing pressure; the stocks undergo size-selective mortality; there are high levels of uncertainty on population densityand stock-recruitment relationship, which increase as abundance declines. The results suggest that the best regulation and management measures in the short-run should be a reduction of 25% in the current fi shing effort.