Whelk (Buccinum undatum L.) stocks around the Island of Jersey, Channel Islands: Reassessment and implications for sustainable management

The exploitation of the common whelk (Buccinum undatum L.) has become an integral part of commercial fisheries in both Jersey and French waters. Since 2004 declining catches have been reported, and it has been suggested that existing management measures may not be effective. This study reports a further 8 years of annual monitoring of whelk catches from 2003 to 2011, using identical methodology and analysis as previous work. Jersey commercial whelk fishermen's logbook returns from 2007 to 2011, were also analysed for changes in effort and catch. Average catch per unit effort (CPUE) dropped by 36.7% from 3.3 kg per pot to 2.09 kg per pot. Since 2007, Fishermen's reported landings per unit effort for whelks, also dropped from 2.12 kg per pot to 1.75 kg per pot. Whilst a decline in catch rates of whelks greater than 44 mm shell length was reported earlier, this study also found catch rates for smaller whelks (<44 mm shell length) had declined by 54.5% from 0.44 kg per pot to 0.2 kg per pot, suggesting the start of possible recruitment overfishing. We found no statistical significance (repeated measures ANOVA) between the sample station grouping of ‘fished’ and ‘non-fished’, as reported previously, for either the small fraction or large fraction of the catch, both of which showed declines in CPUE. Analysis of fishermen's logbook returns showed that effort had varied over time and between statistical reporting areas. It is suggested that, given changes in fishing effort, an earlier grouping of fishing intensity is no longer relevant and we discuss the pitfalls of using such classifications and other arbitrary boundaries for spatial analyses which are then relied upon in making spatial planning and fisheries management decisions. More detailed spatial observations on fishing effort and trans-national sharing of data, along with relevant choices in joint management measures are required for the future sustainability of local whelk stocks.