The population biology of penaeid prawns in the Gulf of Suez, Red Sea, Egypt

Abstract

The prawn fishery in the Gulf of Suez is based on three penaeid species (Penaeus semisulcatus, Melicertus latisulcatus and Marsupenaeus japonicus). The status of the Gulf shrimp fishery was assessed with length frequency distributions from trawl landing data from 1983 to 2008. These data were analysed to determine growth rates, mortality coefficients, biological reference points for fishing mortality from yield per recruit (F max, F 0.1) and maximum spawning potential analysis. The virtual population analysis (VPA) approach was used to obtain point estimates of stock size, recruitment, spawning stock size and fishing mortality rates. Exploitation rates showed a steady state of increase, while the biomass of the three prawn stocks has decreased between 1983 and 2008. This decline is evident from the commercial landings which decreased from 749.4 t in 1983 to 132.9 t in 2008 and in CPUE (catch per unit effort) decreased from 54.7 kg/day to 8.3 kg/day. The size of the spawning stock has decreased by more than 60% of its original size since the beginning of the study period, as has the recruitment number (which decreased from 174 to 35 million recruits for P. semisulcatus, from 275 to 70 million recruits for M. latisulcatus and from 110 to 24 million recruits for M. japonicus). These results indicate that the prawn stocks in the Gulf of Suez are subjected to heavy exploitation and need urgent management regulations. Options for improving and developing the production of prawns in the Gulf of Suez and some implications for fishery management are proposed.