Spawning of plaicePleuronectes platessaL. around the Isle of Man, Irish Sea

The locations and timing of plaice Pleuronectes platessa spawning around the Isle of Man were studied from distributions of recently spawned eggs recorded in plankton samples. The area of intense spawning activity south-east of the Isle of Man was found to be further north than indicated in the literature. A previously disregarded spawning ground off the west coast of the Isle of Man was identified in 1991, 1992 and 1993, although egg densities were lower than off the east coast. Production of stage I eggs on the west coast spawning site was estimated at approximately 2% of the total plaice egg production in the Irish Sea. This would be sufficient to supply the local nursery grounds on the west coast of the Isle of Man with plaice larvae. Plaice spawned between early February and early April off the west coast of the Isle of Man, with March as the main period of egg production. Plaice therefore spawn well before the spring plankton bloom in the Irish Sea.