Variations in settlement pattern of Irish Sea plaice (Pleuronectes platessa L.) as determined from a simulation model

A simulation model for the pelagic phase of Irish Sea plaice was constructed using parameters from the literature to estimate the distribution of settlement dates for the years 1963 to 1996. The numbers of individuals in the egg stages were reduced by age-one herring predation and a general source of mortality. The numbers of individuals in the larval stages were reduced by age-one herring predation and a food-related mortality. The duration of the egg and larval stages were temperature-dependent. Settlement patterns and numbers at metamorphosis were output. Settlement patterns and numbers at metamorphosis are driven by temperature. Increasing the temperature lowers the development time, increases the numbers at metamorphosis and lowers the pelagic daily instantaneous mortality. Later spawning caused later settlement and increased the final peak of settlement. Comparisons with unpublished field data on settlement for Port Erin Bay and data in the literature, showed similar patterns in settlement. However, comparisons with settlement data for 1986 in Red Wharf Bay showed a large difference between simulated and measured settlement pattern. More accurate parameter estimates, a better understanding of the processes in the pelagic phase and a critical evaluation of field estimation techniques are required to produce better models.