Morphometries, length-weight relationship and condition of Rastrineobola argentea (Pellegrin 1904) in the Winam Gulf of Lake Victoria (Kenya)

Abstract

Correlation between total length (TL), fork length (FL) and standard length (SL) of Rastrineobola argente'{ ~ellegrin 1904) in the Winam Gulf of Lake Victoria indicate that FL = 0.92 TL - 0.74 and SL = 0.90 TL - 1.7~. Le~gth-welght relationship of log-transformed data shows that the slopes of the regression lines were 3.06 to 3.22 for juveniles, 2.70 to 3.~5 for males and 3.24 to 3.71 for females. Thee slopes were significantly different between groups at at a = 0,05. The Fulton s condition factor (K) was highest in December (1.019-1.073) and March IApril (1.015-1.030) but lowest in June (1.00-1.025) for all stations. Significant differences between groups demands for the use of different growth models for juveniles: mal~s and females especially for the von Bertalanffy growth equation which uses length-weight relationship. Obse~ed .cycl~cv~n- ations in condition factor suggests two peak breeding seasons for this species in the Winam Gulf. The practical implication of these results in stock assessment using length-based fish stock assessment methods is briefly discussed.