Survival of the Lake Victoria Rastrineobola argentea in a rapidly changing environment: Biotic and abiotic interactions

摘要

In their adaptation to the rapidly shifting environment of the African Great Lakes, small pelagic fish appear to be the most successful fish species. This paper examines the fecundity, size at maturation and the growth and population parameters of Rastrineobola argentea in Lake Victoria. R. argentea may have a low absolute fecundity of a few thousand eggs, but its relative fecundity by weight is enormous: 70 times higher than for L. niloticus and almost 4,000 times that of the tilapia species O. niloticus and O. esculentus. Its food consists mainly of zooplankton, which is superabundant in the environment and for which there is not much competition. In response to increased predation and fishing, the species has reduced its size at maturity as well as its maximum size. Population parameters show a typical r-selected life strategy. The reproductive potential and diet alone do not seem to have enabled R. argentea to thrive as larval densities of R. argentea can be significantly related to a combination of abiotic factors like water conductivity, temperature, Secchi depth and dissolved oxygen concentration.