Effect of Seasonal Variation on Abundance and Sex Ratio Distribution of the Fish Fauna of Ikere Gorge, Oyo State, Nigeria (Published)
The study determined the effect of season on abundance and sex ratio of fish fauna from Ikere-gorge. Fish composition, distribution and abundance were determined. Sexes were also determined and sex ratio calculated. 5,736 fish specimens were caught, identified and classified into 34 species, from 13 families. Chrysichthyes nigrodigitatus was densely and least distributed in station IV (29.98%), and III (19.87%). Lates niloticus was more in station III (3.81%) but significantly lower (p<0.05) than C. nigrodigitatus and Tilapia melanopleura in station 2. C. nigrodigitatus and Sarotherodon galilaeus were present in all sampling months. Sex ratio was skewed in favour of the female populations for C. nigrodigitatus, T. melanopleura and S. galilaeus but towards male for L. niloticus population. No seasonal variation was observed in sex ratio of the species. Conclusively, C. nigrodigitatus, T. melanopleura and S. galilaeus are not threatened in this water but same could not be said for L. niloticus.
Keywords: Chrysichthyes nigrodigitatus, Distribution, Fish composition, Lates niloticus, Sarotherodon galilaeus, Tilapia melanopleura