Publication Abstract

Plankton-generated chaos in themodelled dynamics of haddock

J.W. Horwood

This study illustratesthe feasibility of regimes of chaotic dynamics in gadoid populations. A previouslydeveloped plankton model related fish larval survival to larval density and their copepodfood supply. This model is extended to a full-population model, incorporating agestructure, fishing and a stockrecruitment relation implicit in the plankton model.Parameterization is based upon the Georges' Bank haddock. It is shown that regions ofstability, aperiodic and chaotic-like dynamics exist as both the copepod food-supply andfishing rates are varied. The deterministic aperiodic dynamics are significantlycomplicated by additional stochastic elements. The implications are that chaotic dynamicsare plausible and that analyses of output data on stock and recruitment can revealrelatively little; field and laboratory studies are needed to elucidate the underlyingmechanisms. Traditional fitting of stock and recruitment relations may give an overlyoptimistic interpretation for fisheries managers.

Reference:

J.W. Horwood, 1995. Plankton-generated chaos in the modelled dynamics of haddock. Phil.Transactions of the Royal Society London, B, 350: 109-118.