Aran, Galway Bay and Slyne Head Nephrops Grounds (FU17) 2021UWTV Survey Report and catch scenarios for 2022

Abstract

This report provides the main results and findings of the twentieth annual underwater television survey on the Aran, Galway Bay and Slyne head Nephrops grounds, ICES assessment area; Functional Unit 17. The survey was multi-disciplinary in nature collecting UWTV, CTD and other ecosystem data. In 2021 a total of 44 UWTV stations were successfully completed, 34 on the Aran Grounds, 5 on Galway Bay and 5 on Slyne Head patches. The mean burrow density observed in 2021, adjusted for edge effect, was medium at 0.26 burrows/m². The final krigged burrow abundance estimate for the Aran Grounds was 311 million burrows with a CV (Coefficient of Variance; relative standard error) of 4%. The final abundance estimate for Galway Bay was 12 million and for Slyne Head was 9 million, with CVs of 2% and 2% respectively. The total abundance estimates have fluctuated considerably over the time series. The 2021 combined abundance estimate (331 million burrows) is 16% lower than in 2020, the MSY Btrigger reference and it is below point (540 million burrows). Using the 2021 estimate of abundance and updated stock data imply that catches in 2022 should be no more than 360 tonnes, according to the EU MAP and ICES MSY approach and assuming that discard rates and fishery selection patterns do not change from the average of 2018–2020. Virgularia mirabilis was the only sea-pen species observed on the UWTV footage. Trawl marks were present at 5% of the Aran stations surveyed.