Appraisal of the potential for a future fishery on whelks ( Buccinum undatum) in Swedish waters: CPUE and biological aspects

Abstract

A recent interest in the common whelk Buccinum undatum as a complementary species in the Swedish inshore fishery initiated a controlled trial fishery in 1995. This paper presents estimates of catch per unit effort (CPUE), stock size, maturation, growth, and also reports on the prevalence of imposex and parasites in the Skagerrak and Kattegatt. The spatial distribution of CPUE indicates useful stock sizes, especially in the Kattegatt, where a harvestable stock size in the range of 45 000–225 000 tons was estimated. Both age and size at sexual maturity varied along the coastline. The maturity size was between 52 and 72 mm or 6–9 years of age. Imposex was found in 23–31% of female whelks at two different localities in the Skagerrak and Kattegatt. Parasite load differed significantly between the two sampling localities. Implications of the results for the management of the whelk stocks are discussed. It is concluded that the stocks on the Swedish west coast may be of commercial value, but would be vulnerable to overfishing.