A simple method to estimate the significance level of the catch probability in the catch removal method in river fish populations

This work presents a method for estimating the significance level of the ca pture probability when the capture removal method is used in riverine fish populations. The method is based on adjustment of the linear relationship b etween capture probability and an index of capture efficacy. With this meth od the population size, the statistic chi(2) and the significance level of the capture probability can be estimated. This is a simple technique which can be applied in the field at the time of sampling. It does not require th e use of computers and can determine in situ whether the catch is valid to calculate the population density. (C) 1999 Elsevier Science B.V. All rights reserved.