Western Irish Sea Nephrops Grounds (FU15) 2012 UWTV Survey Report

Abstract

This report provides the main results and findings of the tenth annual underwater television on the ‘Irish sea west Nephrops grounds’ ICES assessment area; Functional Unit 15. The survey was multi-disciplinary in nature collecting UWTV, CTD and other ecosystem data. An analysis of the precision, accuracy and sampling intensity trade-offs showed that sampling intensity could be reduced without significantly reducing the precision and accuracy of the survey. Consequently, sampling intensity was reduced this year from ~150 stations in a 3.5 nautical mile grid to 99 stations (4.5nmi grid). Full coverage of the grid was achieved. The krigged burrow abundance estimate for the Irish Sea ground increased slightly (+3% relative to 2011). Abundance estimates have been fairly very stable over the time series. The 2012 randomised isometric grid design resulted in a CV (or relative standard error) of 3% which is in line with CVs observed previously and well below the upper limit of 20% recommended by SGNEPS 2012.