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Western Irish Sea Nephrops Grounds (FU15) 2018 UWTV Survey Report and catch options for 2019
Clements, A.; Butler, R.; Doyle, J.; Ourens, R.; Lordan, C.; McCorriston, P.; Burns, G.; McCausland, I.; Erskine, K.; Lilley, K.; Heaney, G.; Lundy, M.; Schön, P.J.
This report provides the main results and findings of the 16th 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 2018 design consisted of a randomised isometric grid of 100 stations at 4.5 nautical mile intervals out over the full known extent the stock. The resulting krigged burrow abundance estimate was 4.9 billion burrows. This was a similar result of that obtained in 2011, and 9% lower than the abundance in 2017. In contrast to 2017 the spatial distribution of burrows appears more homogenous across the survey area, with high densities in the SW of the ground in shallower water, and higher densities in the NW of the ground in deep water. Overall densities are high and abundance remains stable, well above MSY Btrigger. Reducing the number of stations compared to 2011 has not affected the accuracy of the survey estimate to date. 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 2018 implies a total catch option at Fmsy (=Fmax) of 11,107 tonnes which results in landings of no more than 8,959 tonnes. The sea-pen species observed in 2018 was predominantly Virgularia mirabilis, with one potential observation of Pennatula phosphorea (which requires verification). Sea-pens were observed at 20% of stations with high densities observed in the south-west of the ground. Trawl marks were noted at 26% of the UWTV stations.
Keyword(s): Nephrops norvegicus (L.); stock assessment; Geostatistics; Underwater television (UWTV); Benthos
Publication Date:
Type: Other
Peer-Reviewed: Unknown
Language(s): English
Institution: Marine Institute
Citation(s): Clements A., Butler, R., Doyle J., Ourens, R., Lordan C., McCorriston P., Burns, G., McCausland, I., Erskine, K., Lilley, K., Heaney, G., Lundy, M. and Schön P.-J. 2018. Western Irish Sea Nephrops Grounds (FU15) 2018 UWTV Survey Report and catch options for 2019. AFBI and Marine Institute UWTV Survey report.
Publisher(s): Marine Institute
First Indexed: 2018-11-09 07:00:04 Last Updated: 2018-11-09 07:00:04