Diel variations in the fish species composition of river Orogodo, southern Nigeria

Abstract

An investigation to assess the diel distribution of fish species in River Orogodo was carried out between January 2006 and December 2007. Fish sampling was conducted monthly for the 24 months based on day and night sampling effort in three different stations of the river. A total of 5,153 (55.83%) and 4,076 (44.17%) individuals were caught during the day and night respectively. Of the 37 species, only 2 species  (Gnathonemus petersii and Gymnarchus niloticus) were restricted to day time catch only, while one species (Mastacembellus leonbergii) was restricted to night catch. The remaining 34 species occurred during both day and night. The dominant day time catch were Clarias gariepinus, Chromidotilapia guentheri, Malapterurus electricus and Erpetoichthys calabaricus, while the dominant night catch include Clarias macromystax, Auchenoglanis occidentalis and A. biscutatus. The results of the study showed that diel variations of fish composition and abundance in River Orogodo was related to the activity pattern of the fish during different times, as more fish were caught when active. The diel variations in fish species composition/distribution of River Orogodo were discussed and compared with the findings of earlier studies conducted elsewhere.

Keywords: Diel variation, fish species, River Orogodo, Nigeria.