THE WESTERN IRISH SEA GYRE - A RETENTION SYSTEM FOR NORWAY LOBSTER (NEPHROPS-NORVEGICUS)

Recently a cyclonic, near-surface, gyre has been discovered above the deep (> 100 m) western basin of the Irish Sea. The gyre is present eac h year only during spring and summer (the surface heating season), and circulates around a static dome of-cold bottom water left beneath the thermocline after the previous winter. The mud substrate of the weste rn Irish Sea is geographically isolated and is the habitat for adult N orway lobster (Nephrops norvegicus). In spring, newly hatched larvae a re released into the water column, spending approximately 50 days in t he plankton. Recruitment depends upon settlement of metamorphosed larv ae onto the mud patch. Larval distributions show a strong corresponden ce to the field of stratification and it is probable that the gyre act s as a retention mechanism, helping to maintain the population on the mud patch.