Impacts of Anthropogenic Activities on the Fish Compositions and Diversity of Okerenkoko Estuarine, Delta State, Nigeria

Abstract

Water quality impairment due to anthropogenic activities affects fishery resources. Surface water bodies in the Niger Delta Region of Nigeria are being adversely impacted by the effects of pollution and the destruction of its fishery resources. This study was carried out to assess the impacts of anthropogenic activities on the fish compositions and diversity of Okerenkoko Estuarine, Delta State, Nigeria. Okerenkoko Estuarine (62.79 Km) was spatially stratified into five stations (Z1, Z2, Z3, Z4 and Z5) based on nearness to major anthropogenic activities. Temporal stratification covered June to December. Fish samples were collected for 7 months from each station at the study area with prior arrangement with the fishers. Fishing gears used were Mid – Water Drift Gill Net of mesh sizes 101 mm and 127 mm; Bottom Set Gill Net (50 – 100 m) of mesh size 76 mm, 101 mm and 127 mm; Hook and line (2 – 6 m) of hook sizes No. 5, No. 7, No. 8, No. 9, No. 12 and No. 15; Long Line (300 – 1000 m) of hook sizes No. 7, No. 8. Parameters determined were Numbers of Species, Abundance (%), Simpson and Shannon by using standard procedures. Data were analysed by using Excel (Window 10) and Palaeontological Statistics (Past Version 3.6). A total number of 1261 of fishes and 45 species belonging to 14 families were identified. Highest 383 (30.4 %) and least 152 (12.1 %) number of fishes were obtained in Z5 and Z4, respectively. The most abundant fish species recorded was Sardinella aurita 192 (15.2 %), while the least was Sphyraena afra 1 (0.1 %), respectively. Temporally, the highest 331 (26.2 %) and least 45 (3.6 %) fish species Occurred in December and September. Simpson index ranged from 0.69 to 0.89 in Z1 and Z3, Shannon (1.97, 2.98) occurred in Z4 and Z2, respectively. Fish biodiversity richness (0.69) of Okerenkoko Estuarine could be threatened. Keywords: Water quality, Anthropogenic activities, Fishing gears, Niger Delta and Pollution