Some thick shelled whelk Buccinum undatum characteristics and fisheries in Ireland

Observations are presented on two whelk populations from the Cape grounds in Co. Donegal and the vicinity of Helvic Head Co. Waterford. Both co-exist with large populations of brown crab (Cancer pagurus) which is the likely explanation for their thick shells. In the south west Irish Sea (with which comparison is made) and in the Cape stocks, 83-88% of individuals were easily aged by reference to the operculum. Heavy calcification obscured structure in the case of Helvic animals and only 6% of these could be confidently aged. Helvic and south west Irish Sea whelk have similar L∞, but both Helvic and Cape whelk have more rapid early growth than in the Irish Sea. The density of whelk in the Helvic vicinity is insufficient to support a commercial fishery. The yield of whelk from other areas of the Celtic Sea is sporadic and slow to recover from exploitation. The Cape fishery shows signs of rapid depletion since most recent exploitation began there in 2003. The centrally situated sectors of the south west Irish Sea fishery are highly resilient and recover rapidly from heavy removals of biomass which can exceed 50% per annum. Maturation appears to take place at a lower size and age in the Irish Sea than in the other two whelk stocks and this is tentatively proposed as the explanation for their lower productivity.

URI

http://hdl.handle.net/10793/187

Citation

Fahy, E., Grogan, S., Byrne, J. & Carroll, J., "Some thick shelled whelk Buccinum undatum characteristics and fisheries in Ireland", Irish Fisheries Bulletin, Marine Institute 2006