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Please use this identifier to cite or link to this item: http://hdl.handle.net/10793/987

Title: Western Irish Sea Nephrops Grounds (FU15) 2014 UWTV Survey Report and catch options for 2015
Authors: Ligas, A.
Doyle, J.
Lordan, C.
Brown, V.
Doran, S.
McArdle, J.
McCausland, I.
McCorriston, P.
Simpson, S.
Schon, J.
Keywords: Nephrops norvegicus
stock assessment
geostatistics
underwater television (UWTV)
benthos
Issue Date: Oct-2014
Publisher: Marine Institute and Agri-Food and Bioscience Institute
Citation: Ligas A., Doyle J., Lordan C., Brown V., Doran S., McArdle J., McCausland I., McCorriston P., Simpson S., and Schön P.-J. 2014. Western Irish Sea Nephrops Grounds (FU15) 2014 UWTV Survey Report and catch options for 2015. AFBI and Marine Institute UWTV Survey report.
Series/Report no.: Version 2 Final;
Abstract: This report provides the main results and findings of the 12th annual underwater television survey on the ‘Irish sea west Nephrops grounds’ ICES assessment area, Functional Unit 15. The survey was multi-disciplinary in nature collecting UWTV and other ecosystem data. The 2014 design consisted of a randomised isometric grid of 101 stations at 4.5 nautical mile intervals out over the full known extent the stock. The resulting krigged burrow abundance estimate was 4.6 billion burrows. This was a similar result of that obtained in 2009, and slightly higher than the abundance in 2013. The spatial distribution shows a decline in abundance in the south-eastern area compared to 2013 figure, while a slight increase is apparent in the North and in the middle of the area. Overall densities remain high and abundance remains relatively stable, well above MSY Btrigger. Reducing the number of stations compared to 2011 is not expected to have significantly affected the accuracy of the survey estimate. The CV (or relative standard error) of 3% is in line with previous estimates and well below the upper limit of 20% recommended by SGNEPS 2012. Total catches and landings options at various different fishing mortalities were calculated and fishing at Fmsy in 2015 implies a total catch option at Fmsy (=Fmax) of 9,922 tonnes which results in landings of no more than 8,223 tonnes. The only sea-pen species observed in 2014 was Virgularia mirabilis and the frequency of occurrence was lower than the average during the investigated period, but higher than in 2013. Trawl marks were noted at 24% of the UWTV stations.
URI: http://hdl.handle.net/10793/987
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