Some Aspects of the Ecology of Lake Macquarie, N.S.W., with Regard to an Alleged Depletion of Fish. XI. Estimation of Fish Populations

Abstract

Estimations of populations of six species of commercial fish were carried out by the mark-and-recapture method using modifications of the calculation methods of Petersen and Schnabel. Results from the two methods do not differ in order of magnitude except in occasional months. The estimates, however, are probably unreal, or refer to a part of the population rather than the whole, as it is doubtful whether tagged fish became randomly distributed throughout the population and migration and mortality must have continued during the period of calculation. It was possible to make an estimate of mortality rate but not of the effects of migration, nor of recruitment.