The contribution of behaviour to the population and fisheries ecology of the American lobster Homarus americanus

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The behaviour (sensu lato) of individuals, and its variation over space and time, affects the structure and dynamics of populations, but is not explicitly considered by the traditional approaches used to study and model animal populations. There has recently been a marked increase in the use of “individual-based” models to study animal populations, where the characteristics of populations emerge as a result of the behaviour (s.l.) (e.g., movements, growth) and interaction of discrete individuals. These individual-based approaches have shed considerable light on demographic patterns and processes in nature. In the marine environment, for example, individual-based spatially explicit bio-physical models have shown considerable potential for predicting larval dispersal in different species of invertebrates and fishes, and have revealed that larval behaviour can markedly limit dispersal (i.e., increase retention) from an area, which in turn can markedly affect demographic and genetic connectivity. These biophysical models are based on physical properties of the environment (e.g., current, temperature) and the biology of individuals of the species of interest (e.g., development at different temperatures, mortality rates, swimming behaviour). Despite these important advances, the role of behaviour in modulating patterns and dynamics of populations is still largely unknown for most species. ******In this Discovery Grant I propose to bring my established research program on the causes and consequences of geographic variation in the phenotype of marine invertebrates to the study of stock structure and connectivity in the American lobster, Homarus americanus, which supports the single-most important fishery in Canada, in terms of landed value and employment. My students and I will quantify variation in i) embryo development rate, ii) embryo size at hatch, iii) larval swimming behaviour, and iv) larval settlement behaviour, among individuals of the same brood (i.e., a same female), different broods (i.e., different females) from the same location, and different broods from different locations throughout the species' range. We will conduct lab and field studies to address different hypotheses concerning the mechanisms and evolutionary significance of this variation, and will use an individual-based bio-physical model to assess its impact on larval dispersal and connectivity between management areas. This research will provide new knowledge and understanding of the patterns, mechanisms, functions and demographic consequences of phenotypic variation in early life stages of American lobsters. It will advance our understanding of the contribution of behavioural and evolutionary ecology to animal populations, and will provide information that is germane to harvesters and managers concerning lobster stock structure and connectivity between management areas.