• Porcupine Bank Nephrops Grounds (FU16) 2016 UWTV Survey Report and catch options for 2017

      Doyle, J.; Lordan, C.; Fitzgerald, R.; O'Brien, S.; Allsop, C.; Kelly, C.; McArdle, J. (Marine Institute, 2016)
      This report provides the results of the fourth 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 2016, adjusted for edge effect, was 0.13 burrows/m². The final krigged abundance estimate was 958 million burrows with a relative standard error of 4% and an estimated stock area of 7,108km2. The 2016 abundance estimate was 32% higher than in 2014. There was no UWTV survey in 2015 due to vessel breakdown prior to survey. Using the 2016 estimate of abundance and updated stock data implies catch of 3,100 tonnes and landings of 3,100 tonnes in 2017 when MSY approach is applied (assuming that all catch is landed). The three species of sea-pen; Virgularia mirabilis, Funiculina quadrangularis and Pennatula phosphorea, were all observed during the survey. The deepwater sea-pen Kophobelemnon stelliferum was also observed and its presence/absence mapped from the available time-series. Trawl marks were also observed on 30% of the stations surveyed
    • Western Irish Sea Nephrops Grounds (FU15) 2014 UWTV Survey Report and catch options for 2015

      Ligas, A.; Doyle, J.; Lordan, C.; Brown, V.; Doran, S.; McArdle, J.; McCausland, I.; McCorriston, P.; Simpson, S.; Schon, J. (Marine Institute and Agri-Food and Bioscience Institute, 2014-10)
      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.
    • Western Irish Sea Nephrops Grounds (FU15) 2015 UWTV Survey Report and catch options for 2016

      Clements, A.; Doyle, J.; Lordan, C.; Brown, V.; Doran, S.; McArdle, J.; McCausland, I.; McCorriston, P.; Simpson, S.; Schon, J. (Marine Institute and Agri-Food and Bioscience Institute, 2015)
      This report provides the main results and findings of the 13th annual underwater television survey on the ‘Irish sea west Nephrops grounds’ ICES assessment area, Functional Unit 15.
    • Western Irish Sea Nephrops Grounds (FU15) 2017 UWTV Survey Report and catch options for 2018

      Clements, A.; Doyle, J.; Lordan, C.; Lundy, M.; McCorriston, P.; McArdle, J.; McCausland, I.; Burns, G.; Schön, P.J. (Marine Institute, 2017)
      This report provides the main results and findings of the 15th 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 2017 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 5.3 billion burrows. This was a similar result of that obtained in 2006, and 4% higher than the abundance in 2016. In contrast to 2016 the spatial distribution of burrows appears more homogenous across the survey area. 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 2017 implies a total catch option at Fmsy (=Fmax) of 11,807 tonnes which results in landings of no more than 9,630 tonnes. The only sea-pen species observed in 2017 was Virgularia mirabilis and this was found at 16% of stations ranging from occasional to common, with high densities observed in the south-west of the ground. Trawl marks were noted at 36% of the UWTV stations.
    • Western Irish Sea Nephrops Grounds (FU15) 2019 UWTV Survey Report and catch options for 2020

      Lundy, M.; McCorriston, P.; McCausland, I.; Erskine, K.; Lilley, K.; Heaney, G.; McArdle, J.; Buick, A.; Graham, J.; Reeve, C.; et al. (Marine Institute, 2019)
      This report provides the main results and findings of the 17th 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 2019 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 4.4 billion burrows. This was a similar result of that obtained in 2015, but a 10% lower than the abundance in 2018. In contrast to 2017 the spatial distribution of burrows shows a high density band on the central western area of the survey ground. The abundance remains within previously observed ranges and is above MSY Btrigger. 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 2020 implies a total catch option at Fmsy (=Fmax) of 10,377 tonnes estimated to result in landings of no more than 8,546 tonnes. Sea-pens were observed at 21% of stations with high densities observed in the south-west of the ground. Trawl marks were noted at 15% of the UWTV stations.