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199. Porcupine Bank Nephrops Grounds (FU16) 2019 UWTV Survey Report and catch scenarios for 2020

Author

Aristegui, M., O’ Brien, S., Tully, D., Galligan, S., McCorriston, P., Bentley, K., and Lordan, C.

Subjects
Nephrops norvegicus, Porcupine Bank, underwater television (UWTV), sea-pens, benthos, geostatistics, stock assessment
Abstract

This report provides the results of the seventh underwater television on the ‘Porcupine Bank Nephrops grounds’ ICES assessment area; Functional Unit 16. The survey was multi-disciplinary in nature collecting UWTV, CTD and other ecosystem data. In total 65 UWTV stations were successfully completed in a randomised 6 nautical mile isometric grid covering the full spatial extent of the stock. The mean burrow density observed in 2019, adjusted for edge effect, was 0.14 burrows/m². The final krigged abundance estimate was 1010 million burrows with a relative standard error of 5% and an estimated stock area of 7,130 km2. The 2019 abundance estimate was 9.5% lower than in 2018. Using the 2019 estimate of abundance and updated stock data implies catches between 2127 and 2637 tonnes in 2020 that correspond to the F ranges in the EU multi annual plan for Western Waters (assuming that all catch is landed). Four species of sea-pen; Virgularia mirabilis, Funiculina quadrangularis, Pennatula phosphorea and the deepwater sea-pen Kophobelemnon stelliferum were observed during the survey. Trawl marks were also observed on 31% of the stations surveyed.

Published
2019

200. The Labadie, Jones and Cockburn Banks Nephrops Grounds (FU20-21) 2019 UWTV Survey Report and catch scenarios for 2020

Author

White, J., Aristegui, M., Blaszkowski, M., Fee, D., O Connor, S., Power, J., Notaro, D. A., O’ Brien, S., and Doyle, J.

Subjects
Nephrops norvegicus, underwater television (UWTV), benthos, Celtic Sea, geostatistics, stock assessment, CTD
Abstract

This report provides the main results of the 2019 underwater television survey on the ‘Labadie, Jones and Cockburn Banks’ ICES assessment area; Functional Unit 20-21. The 2019 survey was multi-disciplinary in nature collecting UWTV, and other ecosystem data. A total of 95 UWTV stations were completed at 6 nm intervals over a randomised isometric grid design. The mean burrow density was 0.06 burrows/m2 compared with 0.27 burrows/m2 in 2018. The 2019 geostatistical abundance estimate was 617 million, a 77% decrease on the abundance for 2018, with a CV of 5% which is well below the upper limit of 20% recommended by SGNEPS 2012. Low densities were observed throughout the ground. Using the 2019 estimate of abundance and updated stock data implies catch in 2020 that correspond to the F ranges in the EU multi annual plan for Western Waters are between 1131 and 1150 tonnes (assuming that discard rates and fishery selection patterns do not change from the average of 2016–2018). One species of sea-pen (Virgularia mirabilis) were recorded as present at the stations surveyed. Trawl marks were observed at 32% of the stations surveyed.

Published
2019

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