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

摘要

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.