FISH POPULATION ASSESSMENT IN A TEMPERATE LOWVELD IMPOUNDMENT OF THE TRANSVAAL, SOUTH-AFRICA

As part of a wider fish ecological study of a temperature North-Easter n Transvaal impoundment, an assessment of the fish stock was made empl oying three methods of mark-recapture population estimation. During th e experiment a total of 21 217 fish were captured, marked and released . Of these, 1 204 were recaptured. With the exception of three of the seven numerically important species studied, the recapture success was statistically sound, providing representative estimates of numbers an d mass which can be expected to approximate those of the actual popula tions. Results showed Oreochromis mossambicus to be the dominant speci es in the impoundment.