Original Articles

PRELIMINARY OBSERVATIONS ON THE FISH POPULATIONS OF THE RECENTLY-IMPOUNDED KATSE RESERVOIR, LESOTHO

DOI: 10.1080/10183469.1997.9631397
Author(s): D. Tweddle, South Africa, M., T.T. DaviesDepartment of Ichthyology and Fisheries Science, South Africa

Abstract

Katse is a new 35 km long impoundment on the Malibamatso River, a highland tributary of the Orange River in Lesotho. Two fishing surveys in 1996 yielded Barbus aeneus, Labeo capensis, Oncorhynchus mykiss and the occasional Austroglanis sclateri. Length frequency data for the first three species show modes which may represent year classes, although gillnet selectivity also plays a role. Barbus aeneus is abundant throughout the reservoir and could support a subsistence fishery. Labeo capensis is segregated by sex in the breeding season, with males remaining on the spawning grounds at the river mouths while females visit the spawning grounds for a short time to shed their eggs. The absence of small-sized Oncorhynchus mykiss in the catch may be due to pollution from mining and construction affecting the spawning grounds. The catches of larger trout and the outstanding scenery suggest that a tourist sport fishery could be developed on the reservoir based on natural recruitment supplemented, if necessary, by stocking hatchery-reared fish. As the three species are potamodromous, subsistence fishing zones will need to be clearly demarcated to prevent fishing in the vulnerable river mouth areas.

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