Distribution and abundance of Parailia pellucida (Boulenger, 1901) (Schilbeidae) in the fresh water reaches of the lower nun river, Niger Delta, Nigeria

Abstract

The vertical and surface distribution of Parailia pellucida was investigated in relation to tidal, seasonal and light or photoperiod variation for 24 months in the freshwater reaches of the lower Nun River. The specimens were caught with gillnets of 8, 12 and 15 mm stretched mesh sizes that measured 35 m in length and 3 m in depth, with a surface area of 105 m 2 respectively. P. pellucida occurred in all transects of the study area being more abundant at the bottom (38%) followed by mid-water (36.2%), while the least of 25.8% occurred at the surface. However, there was no significant difference (p>0.05) in the vertical distribution. In the surface distribution, significantly higher catches (p<0.05) were recorded in the convex area (84.1%) than the central (12.1%) and concave sections (3.8%). Seasonal variation with higher mean catches (p<0.05) in the wet season (12.25) than in dry season (3.93) was observed. There was photoperiod variation with significantly higher catches at night (62.7%) than day (37.3%).The effect of tidal variation was insignificant.


Keywords: Parailia pellucida, Niger Delta, fresh water, seasonal abundance, photoperiod

IJOTAFS Vol. 1 (1) 2007: pp. 30-36