Fisheries Survey of Lake Victoria

[3] The original hand-written 'Naturalists Logbooks' from this survey have recently been re-discovered in the archive of the Centre for Environment, Fisheries and Aquaculture Science (Cefas).

The steam tug SS Kavirondo was chartered from the Kenya and Uganda Railway for the six months in order to deploy fishing gears and provide transportation.

At the time Graham wrote "The introduction of a large predatory species from another area would be attended with the upmost danger, unless preceded by extensive research into the probable effects of this operation".

[9] In the official report of the expedition, Michael Graham wrote that "The ngege or satu Tilapia esculenta, is the most important food fish of the lake, whether for native or non-native consumption.

It is convenient size for trade, travels well and is found in much greater numbers than other important fish, such as semutundu (Luganda), Bagrus sp.''.

[2] Furthermore, Graham noted that "The introduction of the European flax gill-net of 5 inch mesh has undoubtedly caused a diminution in the number of ngege in those parts of the Kavirondo Gulf, the northern shore of the lake, the Sesse Islands and Smith's Sound which are conveniently situated to markets".

[10] Although this species was already locally known as ‘omena’ in Kenya, ‘mukene’ in Uganda or ‘nsalali’ in Tanzania and its artisanal exploitation was reported long before, it was largely unknown to most commercial fishermen until the 1960s.