Effects of salinity on the reproduction of Tilapia guineensis in Niger Delta

Abstract

The effect of salinity on reproduction of Tilapia guineensis in brackish water estuary of Niger Delta was investigated. Adult male and female T. guineensis ofrelatively uniform sizes were paired for spawning in 17ppt, 12ppt, 5ppt and Oppt salinity levels. The treatments were replicated four times in 4 x 7 completely randomized designs. Spawning at different salinities was examined at intervals of 24 hours. Spawning was successful in all the test salinities. However, parents spent more time together before spawning in lower salinities (0 and 5) ppt and fertilization of incubated eggs was significantly higher (P<0.01) in the elevated salinities (12 and 17) ppt. Nevertheless all the fertilized eggs hatched at all treatments levels. The disparity in the duration of hatching among the treatments was not significant (P>0.05). The above finding confirms the euryhalinity of Tilapia guineensis and clearly showed that T. guineensis can tolerate changes in salinity. Also, there is no minimum salinity below which T. guineensis will not reproduce. The delay in spawning and low fertilization at lower salinities could be the cost of acclimatization. Acclimatization of T. guineensis prior to conducting spawning trial on them is therefore recommended for a better result.

Key Words: Tilapia guineensis, Salinity variation, Reproductive biology.