Regional variability in the dynamics of reproduction and growth of Irish Sea plaice, Pleuronectes platessa L

The differences in size-specific fecundity in relation to size/age at matur ity, and in reproductive and somatic investment were analysed for female pl aice caught in four regions of the Irish Sea (Cumbrian coast. Liverpool Bay . Cardigan Bay and western Irish Sea), each of which contains a spawning fo cus. Both the reproductive investment (gonad weight as a function of body s ize) and fecundity-size relationship of plaice in the western Irish Sea wer e significantly different from those in the other regions. Rates of annual somatic growth appeared to fall into three distinct groups (Cumbrian coast: Liverpool Bay and Cardigan Bay; western Irish Sea) and, in all cases, the rate of somatic growth fell rapidly after maturity. The data suggest that t he highest surplus production (as spawned eggs) occurs in the sub-populatio ns of plaice on the Cumbrian coast and in Liverpool Bay, and is linked to r educed intra-specific competition for food. Crown Copyright (C) 2000 Publis hed by Elsevier Science B.V. All rights reserved.