A STATISTICAL STUDY OF ENVIRONMENTAL-INFLUENCES ON BIVALVE RECRUITMENT IN THE WASH, ENGLAND

Recruitment of 2 commercially important bivalves in the Wash (England) is shown to be influenced by atmospheric circulation patterns and pre ceding winter (January and February) mean sea temperature anomaly. The availability of Lamb daily classifications of synoptic weather patter ns over the British Isles permits correlations between weather pattern s and fishery records for the past century. Cerastoderma edule (common cockle) recruitment was high when there was a high frequency of the E asterly Lamb circulation type during the months April to July, and in particular during June. This corresponds with a high frequency of east erly winds. It is hypothesised that these easterly winds induce curren ts which act as a mechanism to retain larvae close to suitable settlem ent sites. Mytilus edulis (common mussel) recruitment was not strongly affected by Lamb circulation types. However, cold winters were associ ated with increased mussel recruitment. Cold winters may reduce or del ay predation due to crabs, thus reducing post-settlement mortality, an d may also induce a reduction in maintenance metabolism, thus increasi ng the quality and quantity of larval production. These results sugges t that events in the plankton may be an important determinant of C. ed ule populations, while they appear to be less important in structuring M. edulis communities.