Some aspects of the ecology of mochokid species in river Ase, Southern Nigeria

Abstract

Some ecological aspects of mochokid catfishes in River Ase, Southern Nigeria were studied for a period of two years (March 1982- February, 1984) using bottom-set drifting nets, surface-set drifting nets, cast nets, drag nets, and atalla lift nets of different mesh sizes. Fifteen species (15) accounting for 303 individuals and wet weight of 46,147.40g were captured. By number and weight, the fifteen species contributed to 7.17% and 13.30% of all total fishes caught respectively. Synodontis schall, Hemisyndontis membraceous and Synodontis budgetti were the prominent species. The monthly condition factors of all the 15 species ranged from 2.30 to 3.60 indicating well-being. Seventy two (72) individuals representing 12 species were captured between 0900 and 1200hrs. On seasonal basis, more fish species and individuals were caught during the rainy season than during the dry season. Apart from Synodontis omias, Synodontis violaceous and Synodontis courteti that were rare and represented by only one individual in some stations, all other species were heterogeneous among the five stations studied. Some ecological aspects of the mochokid species in River Ase have been discussed and compared to the findings of earlier studies carried out elsewhere.

Key words: ecology, mochokids, Ase River, Nigeria