Authors : Francis M. Nwosu
Abstract: The Southern Pink Shrimp, Farfantepenaeus notialis Perez-Farfante 1967 (Decapoda: Penaeidae) is Nigerias foreign exchange earner in the fisheries industry. Fished by both artisanal and industrial fleets, this stock deserves effective management in order to maximize its contributions to national food protein and economy. For assessment of the population biology of this stock, length-frequency data were collected from commercial shrimp landings for two consecutive seasons, 2007 and 2008. Each year was analyzed for population parameters using the FAO-ICLARM Stock Assessment Tool (FiSAT II). Asymptotic length (L∞) and growth rate (K) were 133.93 and 131 mm; 1.65 and 1.55 year-1 for 2007 and 2008, respectively. Mortality coefficients were; total mortality Z = 6.86 year-1 (r = 0.9912) and 9.37 year-1 (r = 0.9987); natural mortality (M) = 1.60 and 1.54 year-1; fishing mortality (F) = 5.26 and 6.44 year-1. The resultant exploitation ratios were 0.77 and 0.69, respectively. The exploitation ratios indicate that this fishery is being over-exploited. Although, information from the trawl catches is lacking in this study, a holistic management approach that would regulate both fisheries is recommended. Of concern should be the incidence of non-native Penaeus monodon in this ecosystem. A stock enhancement program would be desirable for the native Penaeus notialis. Both artisanal and trawl shrimpers should be monitored in order to ensure that a closed period management regulation was respected.
Francis M. Nwosu , 2009. Population Dynamics of the Exploited Penaeid Shrimp, Penaeus (Farfantepenaeus notialis) in the Cross River Estuary, Nigeria. Journal of Fisheries International, 4: 62-67.