Seasonal changes in length-weight relationship and condition factor of Nile tilapia, Oreochromis niloticus (Linnaeus, 1758) (Cichlidae) in Lake Naivasha, Kenya

James Last Keyombe, John O. Malala, Edna Waithaka, Ruth M. Lewo, Benson Ojowi Obwanga

Abstract

The study compared the length-weight relationship and condition factor (K) of Nile tilapia (Oreochromis niloticus) in Lake Naivasha, Kenya, between the wet and dry seasons. Fish samples were collected monthly by gill netting from February to December 2015. A total of 372 samples of O. niloticus were analysed. The b values in the length-weight relationships were observed as 3.077 and 3.366 in the wet and dry seasons, respectively. The values of b exhibited positive allometric growth which were the important indication that the species was growing faster in weight than length. The K values of the fish ranged 1.18-4.1 during the wet season and 0.8-3.0 during the dry season.  All mean monthly K values were found to be greater than 1, the highest being in June (2.33±0.05) and lowest in February (1.31±0.28), an indication of a healthy status and general well-being of the O. niloticus population in Lake Naivasha. The study concluded that seasonal variation has no great influence in the length-weight relationship and condition factor of O. niloticus in Lake Naivasha.

Keywords

Fisheries Biology; Oreochromis niloticus; Lake Naivasha

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