A preliminary quantitative assessment of gillnet fishing in subtropical Lake Tzaneen, Northern Province, South Africa

Abstract

Between January 1998 and January 1999 a quantitative investigation was done on the fish populations of Lake Tzaneen, Northern Province, South Africa. Two graded series of multi-filament gillnets were set overnight every six weeks capturing 14 species of fish. Of the 2692 fish caught, Schilbe intermedius was most abundant both in number and weight. Significantly more fish were caught where the two major rivers, the Great Letaba and the Ramadiepa, enter the lake. The smaller gillnet sizes (30–70mm) caught the highest number of S. intermedius, while the 90mm gillnet caught the highest number of Oreochromis mossambicus. Female S. intermedius greatly outnumbered males. Significant differences were found between the monthly catch per unit of effort and the sampling site catch per unit of effort.

Keywords:

• fisheries potential
• population structure
• freshwater fish
• length-frequency distribution
• catch per unit effort
• Lake Tzaneen
• South Africa