Evaluation of lift-net selectivity in the freshwater sardine Limnothrissa miodon fishery on Lake Kariba, Zimbabwe

Abstract

A study to evaluate the current minimum mesh size on the lift nets in the Lake Kariba sardine fishery was carried out. Data were collected from an experimental rig fitted with a mosquito net fishing next to a commercial rig using the current minimum mesh size net of 8 mm. This mesh size generated an L 50% (length at which 50% of fish are retained by the net) of 21.7 mm with a selection range of 3.5 mm (20.0–23.5 mm). Limnothrissa miodon is reported to attain maturity at 35 mm when it is about 3 months old, which means a larger mesh size would be recommended. This would, however, not be necessary at the moment as long as the regulation that fishing is restricted to areas more than 20 m deep is observed. As only the adult population inhabits these areas, there will be no danger of recruitment overfishing. However, it will be necessary to appraise the minimum mesh size and the appropriate depth from time to time.