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UBC Theses and Dissertations

Field evaluation of the dichotomous population estimation technique Wood, Frederick Ernest Allen


A field evaluation of the dichotomous technique was made using 1965 data from the Rivers Inlet sockeye salmon population. An estimate of preexploitation population size was made with the compositions of the pre- and post-exploitation populations and the catch. The estimate was made through the application of simultaneous equations and a maximum likelihood estimator formulation to changes in population composition resulting from selective removal. Biased data was shown to greatly affect the estimates of population size. A wide range of population estimates was derived from the various dichotomous characters utilized. Graphical analysis of these estimates provided an overall estimate of the population. The physical restrictions of the research area made this estimate of considerable value. Relative to most other population estimation techniques, the dichotomous method has wider potential use because of its less restrictive basic assumptions. This flexibility can be accompanied, however, by a reduction in the accuracy of resultant estimates.

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