Physico-Chemistry, Morphology and Abundance of Finfish of Nkoro River, Niger Delta, Nigeria

Abstract

There have been no reliable data on physico-chemical characteristics, morphology and abundance of fish species from Nkoro River in the Niger Delta Area of Nigeria. This is needed to formulate sound fisheries management and development programmes in the Nkoro River. This paper therefore provides information to fill that gap in Nkoro River fisheries by studying some physico-chemical parameters and  morphology and abundance of five fish species. Temperature, pH, dissolved oxygen and salinity were monitored using standard methods. Fish samplings were carried out for twelve months biweekly from January to December 2006 from the artisanal fishers using cast nets, beach seine and canoes. The monthly physico-chemical characteristics showed that, salinity values ranged from 5‰ (September) to 17‰ (February and March). Dissolved oxygen values ranged from 6mg/l(January, April, July and October) to 10mg/l (September). pH values ranged from 6.1(August) to 8.5(November) and Temperature values ranged from 24oC (July) to 32oC (March). There was no significant difference in salinity and pH between stations, but dissolved oxygen, and temperature showed significant differences between stations (P<0.05). The monthly catch per unit effort values ranges were: E. fimbriata [(0.20 (November) to 8.16 (January)]; I. africana [0.1 (May) to 1.6 (February); S. maderensis [0.04 (October) to 6.8 (December]; C. senegalensis [0.12 (August) to 2.45 (December)] and C. senegalensis [0.11 (May) to 1.62 (December)] . There was an increase catch during the dry season. There was significant difference in monthly catch (P>0.05). There was no correlation between any of physio-chemical parameters and catch. The test for correlation between the condition factor and the physico-chemical parameters was negative except for temperature (only temperature showed slight correlation). The variation was significant between various stations. Salinity in Nkoro River played a major role in distribution and abundance of the five fish species; higher abundance of fish species during low salinity.