The assessment of the stock is based on Underwater TV (UWTV) surveys, conducted since 2006, and the length structure and sex ratio of catches. Discards are contemplated in the assessment. There are also landings and effort data from Nephrops-directed fleets. These are mainly not corrected for changes in fishing power or efficiency. Owing to uncertainties in the accuracy of historic landings in some fisheries, increasing attention is paid to survey information and size composition in the catch data as an indicator of stock stability.
Sampling of the stock is at a strong level. A benchmark assessment is planned in 2013. UWTV surveys are precisely estimated but estimates of bias are provided by experts. Uncertainties in projections relate largely to discarding and mean weight in landings (ICES, 2012a).
ICES previously advised for this fishery together with the remainder of the Celtic Sea fishery. From 2011, advice has been provided separately for Functional unit (FU) 22 and based on the MSY approach. For 2013, landings are advised to be kept below 3,100 tons. Management measures should be implemented at the FU level (ICES, 2012a).
A proxy reference point for fishing mortality leading to Maximum Sustainable Yield (MSY) has been selected according to determining factors affecting the biology of the stock and the nature of the fishery. Considering the moderate productivity of the stock in FU 22 and its long and stable history, FMSY is based on F35%SpR combined between sexes, and set at 10.9%. This is considered to be preliminary and may be modified in future assessments. The time-series is still too short to determine a MSY biomass reference point, and precautionary reference points have not been determined (ICES, 2012a).
Based on the results of UWTV surveys, the stock is increasing and ICES considers its status to be stable, but no reference points are defined for abundance. Fishing mortality is safely below its MSY proxy reference point and is on a decreasing trend.
Landings are relatively stable in the range of 1,500 to 2,500 tons per year. Survey abundance decreased to 2009 but has been on a slow increasing trend since then. Harvest rates have decreased overall since peaking in 2007.