TY - JOUR

T1 - The complexities and challenges of conserving common whelk (Buccinum undatum, L.) fishery resources: Spatio-temporal study of variable population demographics within an environmental context.

AU - Emmerson, Jack

AU - Haig, Jodie

AU - Bloor, Isobel

AU - Kaiser, Michel

PY - 2018/8

Y1 - 2018/8

N2 - The commercial fishery for common whelk (Buccinum undatum L.) has expanded significantly in the Irish Seasince 1990 and continues to grow, particularly in Welsh waters and the Isle of Man territorial sea, with landingsthroughout the region increasing by 227% between 2011 and 2016. Whilst whelk populations are known to bevulnerable to localised overexploitation due to inherent life-history parameters, fisheries remain relatively unrestrictedby conservation measures in comparison to other fisheries operating in the area. With the exceptionof the northernmost fishing ground between the Isle of Man and Scotland (Point of Ayre), the size-at-maturity(L⁠50) estimate for populations sampled during peak-aGSI (the months in which adjusted gonadosomatic index ishighest) indicates that whelk are being fished before the time at first spawning throughout the study area. A correlationwas detected between the size (total shell length) and depth, with smaller whelks found in deeper waterswhere there generally is greater fishing effort, although effort data is not available at a resolution to investigatethis relationship quantitatively. No clear link between benthic infauna biomass and the average size (total shelllength) or reproductive capacity (aGSI) of whelk sampled throughout ICES Area VIIa was found, indicating thatthe ecological energetics of whelk populations are more likely to be a function of scavenging opportunities thanpredation on benthic communities. A mixed cohort analysis utilized length-based data to infer a size-at-age relationshipin the absence of direct age observations (e.g. statolith rings), with whelk recruiting into the Isle ofMan fishery five years after hatching. The evidence presented in this study suggests that, prior to recommendinga MLS that will adequately protect the spawning stock biomass, L⁠50 values should be adjusted for pre-spawninggrowth between the ideal time of assessment (when aGSI values are at a peak) and the spawning season (whenaGSI values decrease).

AB - The commercial fishery for common whelk (Buccinum undatum L.) has expanded significantly in the Irish Seasince 1990 and continues to grow, particularly in Welsh waters and the Isle of Man territorial sea, with landingsthroughout the region increasing by 227% between 2011 and 2016. Whilst whelk populations are known to bevulnerable to localised overexploitation due to inherent life-history parameters, fisheries remain relatively unrestrictedby conservation measures in comparison to other fisheries operating in the area. With the exceptionof the northernmost fishing ground between the Isle of Man and Scotland (Point of Ayre), the size-at-maturity(L⁠50) estimate for populations sampled during peak-aGSI (the months in which adjusted gonadosomatic index ishighest) indicates that whelk are being fished before the time at first spawning throughout the study area. A correlationwas detected between the size (total shell length) and depth, with smaller whelks found in deeper waterswhere there generally is greater fishing effort, although effort data is not available at a resolution to investigatethis relationship quantitatively. No clear link between benthic infauna biomass and the average size (total shelllength) or reproductive capacity (aGSI) of whelk sampled throughout ICES Area VIIa was found, indicating thatthe ecological energetics of whelk populations are more likely to be a function of scavenging opportunities thanpredation on benthic communities. A mixed cohort analysis utilized length-based data to infer a size-at-age relationshipin the absence of direct age observations (e.g. statolith rings), with whelk recruiting into the Isle ofMan fishery five years after hatching. The evidence presented in this study suggests that, prior to recommendinga MLS that will adequately protect the spawning stock biomass, L⁠50 values should be adjusted for pre-spawninggrowth between the ideal time of assessment (when aGSI values are at a peak) and the spawning season (whenaGSI values decrease).

U2 - 10.1016/j.fishres.2018.02.015

DO - 10.1016/j.fishres.2018.02.015

M3 - Article

VL - 204

SP - 125

EP - 136

JO - Fisheries Research

JF - Fisheries Research

SN - 0165-7836

ER -