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.