Some Aspects of the Ecology of Lake Macquarie, N.S.W., with Regard to an Alleged Depletion of Fish. X. The Movements of Fish.

Abstract

Of 20,128 fish of 29 species tagged, 9.4 per cent. were recovered by commercial fishermen and anglers. A further 1.5 per cent. were retaken by the tagging crew. Only 11 species were tagged in numbers greater than 100. Returns covered 17 species, showing recovery rates varying from 1 to 21 per cent.

Some exchange of fish takes place between the northern and southern parts of the lake, but this is consistent only in the case of the flat-tail mullet. Within the two parts of the lake lateral movements of some species take place; other species are sedentary. These facts suggest that the necessary condition for population estimation, that tagged fish should be randomly distributed amongst the population, is not achieved for most species.