Length at first capture for Bonga, Ethmalosa fimbriata in Nigerian Inshore waters and management implication

Abstract

The Length at first capture for Bonga in Nigeria inshore water was investigated. The selectivity study was done by comparing the catches of gill net with the catches of purse seine net operating in the same area. The length at first capture (Lc) is 21cm, the length at which 75% is retained is 21.7cm while the maximum retentive length (Lm) is 22cm. Bonga grows out of selection range by virture of large size at a total length greater than 23cm (Ld). LC and Lm correspond to age group of 2 and 3 years respectively. This implies that young of the year and one year age cohorts are not recruited into the fishery. Closed season and area in Nigeria inshore waters alone has no conservative effect on inter E.E.Z’s migratory species like Bonga. Closed season and area in the lagoon, estuary, and creeks are suggested to protect the juveniles in their nursery grounds as well as the use of gillnet with mesh size >70 mm in the inshore water.