Aspects of the biology of trap caught Chrysichthys nigrodigitatus (Lacepede: 1803) from theNew Calabar River, Nigeria

摘要

Length and weight measurements of a population of 513 specimens of trap-caughtChrysichthys nigrodigitatus??harvested between January and July (excluding May), 2010 were analyzed using the following softwares; FiSAT (Fish Stock Assessment Tool) and Popdyn JFB.xls. Results of the sampled population gave a total length range of 18 to 95 cm, ?Lmax (113.8 cm), L∞ (116.8 cm), Lm (60 cm), Lopt (75.9 cm), ?and ?weight; 100 to 12,000 g ?indicating ?the promising nature of this trap fishery to make significant contribution to food security and socio-economic development if effective management of the fishery can be developed and enforced. ?The high percentage of occurrence (76%) of length at first maturity Lm is suggestive of the need for more confirmatory research that can lead to the enactment of a limited access fishery law in the form of closed season and closed area along this river system. The negligible occurrence of small sized individuals from catches indicated the appropriateness of this cylindrical metal trap as gear for the sustainable exploitation of?C. nigrodigitatus?fishery.