Abstract
M.Sc.
At present large scale extensive cropping of fish populations
of impoundments is being undertaken by the agricultural departments
of the government of the Republic of Venda and selfgoverning
states of Lebowa and Gazankulu. Parasitological
surveys coinciding with the cropping program revealed that Clarias
gariepinus (Burchell, 1822) and Oreochromis mossambicus
(Peters, 1852) were infested by fish lice of the genus Dolops
(Crustacea: Branchiura). A study was therefore initiated to
examine the extent of these infestations and other impoundments
in Transvaal were also included.
A total of 14 localities in Transvaal extending from Bloemhof
Dam in the Southwest to Luphephe and Nwanedzi Dams in the Northeast
were surveyed during 1982 and 1983. At these localities
fish were collected by means of gill nets, seining and electrofishing
techniques. The collected fish were examined in a
field laboratory at the collection localities for the presence
of ectoparasitic Dolops. The fish were weighed and measured
and the site of attachment of the parasites, if present, were
recorded. The parasites were removed and fixed in either hot
formalin or AFA. A number of parasites were transported alive
to the laboratory in Johannesburg where they were kept in glass
aquaria and their life cycle studied.
A morphological description based on light microscopy as well
as scanning electronmicroscopy of the eggs, larvae and adults
were made, and comparative body dimensions of parasites from
various localities recorded. It was found that only one species
of Dolops that is D. ranarum (Stuhlmann, 1891) occurred
in Transvaal. This parasite was found in only five of the 14
examined localities of which all were situated in Northern
Transvaal, north of the watershed.