Production cycles and carryng capacity of spiny lobsters, Panulirus spp., stocks on the continental shelf of Ceará State, Brasil

Abstract

The lobster fishery was assessed as to its historical production cycles, suitability of the calcareous algae substrate for the species Panulirus argus and Panulirus laevicauda, and their carryng capacity and standing stock. The main source of information was the long series of data on yield, fishing effort and catch per unit effort in Ceará State, from 1974 to 1995. The fishing activity went throught the phases of Development, Acceleration, Stabilization and Depletion and, in recent years, it is showing all features of the latter one, such as downward trend of production, positive growth rates of fishing effort (b = 1,812 and G = 4.1% per year) and negative growth rates of catch per unit effort (b = - 0.0387 and G = 3.7% per year). The continental shelf off Ceará State is endowed with outstanding environmental conditions for the calcareous algae substrate to be formed and make up the ideal habitat for tropical spiny lobsters. This region holds 27.6% (23,088 sq km) of the total area, 52.3% of the catch, 43.5% (7,301,355 kg) of the carrying capacity and 42.9% (7,398,883 kg) of the standing stock. Species P. argus and P. laevicauda have 68.9% and 31.1% of the overall biomass, the former being more abundant from the 30-m isobath onwards. Catchhability is 55.6% and optimum fishing intensity and density rates are 5.1 individulas/ha and 9.1 individuals/ha.