Synchrony in the recruitment time-series of plaice ( Pleuronectesplatessa L) around the United Kingdom and the influence of sea temperature

Abstract

Historical time-series of recruitment to plaice stocks around the United Kingdom were examined for evidence of synchrony. Correlations were significant for most pair-wise comparisons and a meta-analysis test over all the stocks was highly significant. Previous studies on plaice recruitment in the North Sea have suggested that a negative relationship exists between sea temperature, during the first few months of the year, and subsequent year-class strength. When we examined the correlations between sea surface temperature and plaice recruitment, we found statistically significant negative relationships for most areas. These were strongest for the period February–June. Our results are consistent with the hypothesis that the temperature effect on recruitment of North Sea plaice is due to changes in predation pressure on the planktonic stages. However, western (North Sea and Channel) and eastern (Irish Sea and Celtic Sea) stocks appeared to respond to different time-scales of temperature variability which may imply that different mechanisms could be operating in these stocks. Management of plaice is based upon projections of future stock dynamics. Compared with fisheries on some other species, those on plaice are less dependent on the in-coming year-class. Therefore, the incorporation of sea temperature data into plaice stock dynamic models will probably not have a large impact on short-term projections. However, incorporation of a temperature relationship will allow medium to long-term forecasts to be made under varying environmental scenarios. These may provide a more realistic range of projections of future stock trends than is currently achieved.