Publication Abstract

The stock structure and migrations of plaice populations on the west coast of England and Wales

M R Dunn and M G Pawson

Plaice on the west coast of England and Wales are currently managed as two stocks: in ICES Division VIIa (the Irish Sea, Cardigan Bay and St George’s Channel), and ICES Divisions VIIf&g (the Bristol Channel and Celtic Sea). However, there is some doubt over the biological integrity of plaice populations in these two areas, particularly in relation to stock assessments based on catch-at-age data (ICES>>) and egg production methods (Armstrong et al., 2001). To this end, a total of 13,784 plaice were fitted with Petersen tags and released in these areas during 1979-80 and 1993-96. Analysis of the 2,788 recaptures received by June 2000 confirmed known spawning and feeding grounds in the region, and showed that plaice above a threshold length of 25cm were likely to undertake extensive spatial movements. At this size, female plaice were were likely to be maturing for the first time, whilst males were probably mature. The tag recaptures indicate resident sub-stocks of plaice in the north-east Irish Sea, the south-east Irish Sea, Cardigan Bay, and the Bristol Channel, with a contingent of plaice which originated in the south-east Irish Sea migrating to spawn in the Bristol Channel. Plaice originating in the Bristol Channel rarely moved north into ICES VIIa. A general hypothesis of plaice population structure in the region is presented using these and published tagging results, historical and seasonal fishery patterns, and growth and maturity studies.

Reference:

M.R. Dunn and M.G. Pawson, 2002. The stock structure and migrations of plaice populations on the west coast of England and Wales. Journal of Fish Biology, 61(2): 360-393.