SIMULATING WINTER FLOUNDER POPULATION-DYNAMICS USING COUPLED INDIVIDUAL-BASED YOUNG-OF-THE-YEAR AND AGE-STRUCTURED ADULT MODELS

Population dynamics of winter flounder (Pleuronectes americanus) are s imulated using a detailed individual-based model for young-of-the-year coupled to an age-structured matrix model for adults. When run alone, the young-of-the-year model is initiated with user-specified female s pawners. When coupled to the adult model, multiple-year simulations ar e performed with young-of-the-year survivors inputted to the adult mod el and the adult model is used to generate the female spawners each ye ar. Model predictions of young-of-the-year densities, growth rates, an d mortality rates were within the range observed for the Niantic River population. Model predictions and Niantic River data both showed recr uitment (survivors to age 1) to level off at high numbers of spawners. Predicted recruitment at high numbers of spawners was two to three ti mes that for the same conditions under density independence. Analysis of a 200-year simulation indicated that recruitment was largely set by metamorphosis, with density-dependent growth and survival rates opera ting during the larval and juvenile life stages. The relationship of o ur modelling approach to previous approaches, the implications of our results to understanding winter flounder population dynamics, and poss ible further elaborations of the model are discussed.