Some biological and ecological considerations for research in the management of the fisheries of Lakes Victoria and Kyoga

摘要

There is little doubt that the exploitation of the currentudfisheries of Lakes Victoria and Kyoga requires close monitoring with a view to enforce adherence to prudent management practices. Many indigenous fishes have gradually disappeared from the commercial fishery of both lakes. In the Uganda portion of Lake Victoria for instance Okaronon and Wadanya (in press)udhave shown that:-ud1. The once preponderant haplochromiine taxon ceased toudfeature in the commercial catches in 1979.ud2. The lung-fish (Protopterus aethiopicus) whichudformerly contributed significantly to the commercial landings had declined to minor species status by the mid 1980s.ud3. The catfishes Clarias mossambicus and Bagrus docmac,udformerly major fish species, contributed insignificantudquantities to the commercial fishery since the earlyudand mid 1980s, respectively.udSimilar trend have been "reported in the Kenya and Tanzaniaudportions of Lake Victoria (Bwathondi, 1985; Mainga, 1985, Witte and Goudswaard, 1985).udOn the other hand since their establishment all round theudlake in the early to mid 1980s some introduced fishes namely Nile perch (Lates niloticus) and Nile tilapia (Oreochromis niloticus) built up impressive stocks in Lake Victoria (Ssentongo and Welcomme, 1985, Okaronon et al. 1985; Okaronon and Wadanya, in press). Togetther with the native pelagic cyprinid Rastrineobola argentea or Dagaa/Mukene the introduced fishes have contributed unprecidented catches, stimulating vibrant commercial fisheries which have yielded significant social economic benefits to the peoples of the three states riparian to the Lake (Reynolds and Greboval, 1988; Kudhongania et al in press). The impressive landings particularly of the Nile perch and Nile tilapia have also led to rapid industrialisation of fish processing in East Africa mainly for the export market. Fish export has now the potential of a major foreign exchange enterprise in the region.