POPULATION DYNAMICS AND FISHERIES REGULATIONS FOR THE EUROPEAN SEABASS DICENTRARCHUS LABRAX (MORONIDAE) AT BARDAWIL LAGOON, EGYPT

Abstract

The European seabass Dicentrarchus labrax at Bardawil lagoon was assessed using Beverton and Holt relative yield per recruit model. A total of 1419 specimens were collected between April 2008 and December 2008 (one fishing season). The maximum life span was eight years for length range of 20 – 71 cm TL. The parameters of the von Bertalanffy growth function were K = 0.29 year -1 , L∞ = 76.36 cm and t0 = -0.19 years. The rates of total mortality Z, natural mortality M and fishing mortality F were 1.54, 0.36 and 1.18 year -1 respectively. The exploitation level of this species was higher than the optimum one where the current E was 0.766 indicating that the population of this species is being heavily exploited. Yield per recruit analysis revealed over-fished stock conditions particularly because small fish are effectively unprotected by current minimum size regulations. Based on the analysis it is recommended that the commercial fishery of Bardawil lagoon should be subjected to a total allowable catch, bag limits should be lowered and a maximum size limit be implemented. Kalsa fishing technique (trawl) should be completely prohibited in the lagoon and the future work should be directed to introduce new fishing techniques for crustacean. Also, eggs and larvae survey should be established to develop a biomass database that would help in determining year-to-year optimum exploitation strategy.