Management of the Nile perch, Lates niloticus fishery in Lake Victoria in light of the changes in its life history characteristics

Nile perch was introduced into lakes Victoria and Kyoga in the 1950s and 1960s from Lake Albert. The changes in prey eaten and the life history characteristics of Nile perch in lakes Victoria and Kyoga from the 1960s to 1990s were examined and compared with Lake Albert. The dominant prey eaten changed from haplochromines, Caridina nilotica, Rastrineobola argentea, and Nile perch juveniles. The condition factor deteriorated from 1.4 in 1960s to 1.2 in 1990s, compared with 1.3 in Lake Albert suggesting a reduction in food supply. Therefore, exploitation of Nile perch prey should be controlled. The size at first maturity increased from 30–40 to 40–50 cm and 50–59 to 80–100 cm for males and females, which is similar to Lake Albert. Sex ratios decreased from 85–100 to 20–65 females for every 100 males suggesting that Nile perch had less capacity to replenish its stocks such that breeding females should be protected. As males mature at 50–55 cm and females at 80–100 cm, immature males of <50 cm and breeding females of >100 cm could be protected through size selective exploitation of fish of 50–100 cm using gillnets of 127–254 mm.