Diel variations in the fish species of River Ase, Niger Delta, Nigeria

Abstract

The diel variations of 100 fish species based on three hourly sampling intervals of fishing efforts in River Ase, Niger Delta, Nigeria were studied for two years, March 1982 - February 1984. A total of 91 and 70 fish species were captured during the day and night respectively. More fish species were caught between 0600 and 0900(h) accounting for 1,229 (29%) out of 4,226 individuals of all fish captured than at other time intervals. A total of 2,669 (63.20%) and 1,557 (36.80%) individuals were caught during the day and night respectively. Diel variations were related to the activity of the fish during the different time intervals of the day as more fish are caught when active. The diel variations in fish species of River Ase have been discussed and compared with the findings of earlier studies conducted elsewhere.

Keywords: fish species, diel variations, fish activity, river, Niger Delta, Nigeria

Tropical Freshwater Biology 2003/2004 Vol. 12/13: 63-76