SOME ASPECTS OF THE REPRODUCTION BIOLOGY OF LABEO CAPENSIS (SMITH, 1941) (PISCES, CYPRINIDAE) IN RELATION TO EXPLOITATION AND EXTREME ENVIRONMENTAL CONDITIONS IN HARDAP DAM, NAMIBIA

Abstract

The sex ratio of Labeo capensisdid not differ significantly at a 95% confidence level from a 1♂:1♀, ratio during the study period. The smallest sexually mature male and female L. capensis were 20 cm and 21 cm FL, respectively. Fifty percent of the males matured at 23 cm FL whereas females matured at 26 cm FL. In large ripe females (> 38 cm FL) the ovaries were as much as 15% of body mass. The males and females are two to three years old when they reach the minimum length at maturity. A linear relationship between fish mass and fecundity was obtained. The gonads of the males and females started enlarging during August, reached a peak during December to January and gradually decreased in size by February. Water temperature correlates with the development of the gonads in both male and female L. capensis, and the decrease in gonado-somatic index shows that spawning is not dependent on flooding.