Exploring the Dynamics of Gillnet Fishing in the Lower Nun River: A Study of Selectivity, Seasonal, Tidal, and Photoperiod Effects

Abstract

The fish species of the lower Nun River was sampled to determine gillnet selectivity and the effect of 
season, tide and photoperiod variation on the catch. A total of 11,156 specimens were caught belonging 
to 14 families consisting of 25 species. Gillnet selectivity was observed with a declining trend from the 
largest mesh size net of 15 mm (58%) in number and 59% by weight, 12 mm (33%) in number and 33% 
by weight with the least catch of about 9% by number and 8% by weight from the smallest (8 mm) net. In 
terms of seasonal variation, the rainy season catches were significantly higher (P< 0.05) than the dry 
season with relative abundance of 67 and 32% respectively. Tidal variation in the catches showed that 
catches were higher during the low tidal period (61%) than the high tide (39%). Significant photoperiod 
differences (P < 0.05) were observed with higher catches by day (58%) than by night