PRELIMINARY EVALUATION OF SOME ASPECTS OF BIOLOGY OF TWO COMMERCIALLY IMPORTANT FISH SPECIES IN OKRIKA ESTUARY (NIGER-DELTA) OF NIGERIA

Abstract

Preliminary investigation of length-weight relationships and condition factors of two commercially important fish species, Tilapia, Sarotherodon melanotheron and silver catfish, Chrysichthys nigrodigitatus, from Okrika estuary was conducted from October, 2015 to February, 2016. A total of 60 samples (based on financial resources available) of the two fish species were caught by fishermen using various fishing gears. The results obtained showed that the two fish species had negative allometric and isometric growth patterns with the growth exponents, b values of 2.50 and 3.16 respectively. The condition factors, K of both species were 6.6 and 0.44 which indicated that Tilapia was good condition while the environment was not favourable for silver catfish. This study was necessary to fill the new knowledge gap and provide baseline and first documented information for management and conservation of the two investigated species in Okrika estuary. This study recommended that further research needs to be conducted because of the sample size of the two fish species collected and sampling duration (4 months), thereby requires longer and deeper investigations.