PLANKTON-GENERATED CHAOS IN THE MODELED DYNAMICS OF HADDOCK

This study illustrates the feasibility of regimes of chaotic dynamics in gadoid populations. A previously developed plankton model related f ish larval survival to larval density and their copepod food supply. T his model is extended to a full-population model, incorporating age st ructure, fishing and a stock-recruitment relation implicit in the plan kton model. Parameterization is based upon the Georges' Bank haddock. It is shown that regions of stability, aperiodic and chaotic-like dyna mics exist as both the copepod food-supply and fishing rates are varie d. The deterministic aperiodic dynamics are significantly complicated by additional stochastic elements. The implications are that chaotic d ynamics are plausible and that analyses of output data on stock and re cruitment can reveal relatively little; field and laboratory studies a re needed to elucidate the underlying mechanisms. Traditional fitting of stock and recruitment relations may give an overly optimistic inter pretation for fisheries managers.