Some reproductive aspects of species of Labeobarbus (cyprinidae: teleostei) in Gilgel Abay river and its tributaries, Ethiopia

Abstract

Six sampling sites of Gilgel Abay River and its tributaries, were sampled by using monofilaments (5-55 mm) and gillnets having mesh sizes of 6, 8, 10, 12 and 14 cm stretched bar mesh with a length of 25 m and depth of 1.5 m, twice each month from August to October, and once in November, 2011. Fishes were identified to the species level. Fork length (FL), total weight (TW) and gonad weight (GW) of each specimen were measured. The relationship between FL and TW for the dominant species of Labeobarbus showed curvilinear relationship. Condition factor of L. intermedius, L. brevicephalus and L. nedgia showed that there was significant difference (p<0.001) between sexes in all three species. In all catch, females were more numerous than males. The highest GSI (15.54%) was recorded for L. brevicephalus but the maximum mean monthly GSI (7.01%) was recorded for L. longissimus in September and minimum GSI (0.45%) for L. macrophtalmus in August. Absolute fecundity, mean fecundity and mean FL for L. intermedius was the highest than the rest. The relationship between absolute fecundity (AF) and FL, TW, and GW of L. intermedius, L. brevicephalus, and L. nedgia were linear (AF=596.4FL 8990, R²=0.79; AF=19.78TW+978.1, R²=0.79 and AF=371.5 GW+573.5, R²=0.93). There was also strong relationship between AF and FL, TW, and GW (p<0.001) in the three species.

Key words/phrases: Abay basin, Condition factor, Conservation, Fecundity, Lake Tana