Counting All the Imaginary Fish and More

Abstract

Avoiding overexploitation of marine resources requires being able to accurately estimate the size and health of a population. This thesis presents methods that improve upon existing fisheries stock assessment methods. Having an estimate of the ages of fish in a sample can simplify stock assessment model development and allow more insight into stock structure. We first present a spatial Age Length Key (ALK) model that accommodates physical barriers to fish movement such as islands or bays. By incorporating spatial information and accounting for barriers in the construction of ALKs more accurate estimates of age can be obtained. We then turn our attention to effective population size, a concept used by conservationists and geneticists to summarize the overall genetic health of a population by giving the size of the population under the "ideal" Wright-Fisher model. We show how using CKMR alone it is possible to estimate the effective population size as well as the variance in number of offspring enabling new insights into the population. Finally, we examine the applicability of CKMR to a population similar to the Sable Island grey seal colony through individual based simulation.