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    AuthorDoyle, J. (6)Lordan, C. (6)Fitzgerald, R. (4)O'Connor, S. (4)Sheridan, M. (3)Simpson, S. (3)Blaszkowski, M. (2)Hannify, O. (2)Hehir, I. (2)Keith, M. (2)View MoreSubjectbenthos (6)
    geostatistics (6)
    Nephrops norvegicus (6)
    stock assessment (6)
    underwater television (UWTV) (6)
    CTD (4)Celtic Sea (1)Porcupine Bank (1)View MoreDate Issued
    2014 (6)

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    Aran, Galway Bay and Slyne Head Nephrops Grounds (FU17) 2014 UWTV Survey Report and catch options for 2015.

    Hehir, I.; Doyle, J.; Lordan, C.; O'Cuaig, M.; Hannify, O.; Fitzgerald, R.; O'Connor, S.; Keith, M.; Murphy, Á.; Sheridan, M.; et al. (Marine Institute, 2014-10)
    This report provides the main results and findings of the thirteenth annual underwater television on the Aran, Galway Bay and Slyne head Nephrops grounds, ICES assessment area; Functional Unit 17. The survey was multi-disciplinary in nature collecting UWTV, fishing, CTD and other ecosystem data. In total 33 UWTV stations were successfully completed in a randomised isometric grid design at 3.5nmi or 6.5km intervals over the known range of the stock on the Aran Grounds. The mean burrow density observed in 2014, adjusted for edge effect, was 0.29 burrows/m². The final krigged burrow abundance estimate was 287 million burrows with a CV (or relative standard error) of 4 %. Abundance estimates have fluctuated considerably over the time series. The 2014 abundance estimate was 9% lower than in 2013 and the lowest estimate in the 13 year time series. Raised abundance estimates for Galway Bay and Slyne Head were also low for those areas. Using the 2014 abundance estimate together with updated parameters for mean weight and proportions of removals retained implies catch advice, fishing at Fmsy (=F35%spr), of 584 tonnes and landings of 524 tonnes in 2015. Nephrops accounted for approximately 70% of the benthic catch by weight from 5 beam trawl tows. The relatively high numbers caught around 15 CL mm (carapace length) may indicate strong incoming recruitment. Virgilaria mirabilis was the most common of the two sea-pen species observed on the UWTV footage. Funiculina quadrangularis was observed at one station on the Slyne Head Nephrops ground.
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    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.
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    FU19 Nephrops Grounds 2014 UWTV Survey and catch options for 2015

    Lordan, C.; Doyle, J.; Fitzgerald, R.; O'Connor, S.; Blaszkowski, M.; Simpson, S. (Marine Institute, 2014-10)
    This report provides the main results and findings of the fifth underwater television survey of the various Nephrops patches in Functional Unit 19. The survey was multi-disciplinary in nature collecting UWTV, CTD, multi-beam and other ecosystem data. In 2014 a total 40 UWTV stations were successfully completed. The mean density estimates varied considerably across the different patches. The 2014 raised abundance estimate of 636 million burrows was a 31% increase from the 2013 estimate. Taking into account the uncertainty (CV of 15%) this is not significantly different from abundance estimates since 2011. Using the 2014 abundance and recent mean weight and discard parameters would imply total catches of 1119 t fishing at Fmsy in 2015. Based on recent discard patterns which are high in this area; 715 t would be landings and 404 t would be discards. Two species of sea pen were observed; Virgularia mirabilis and Pennatula phosphorea, both species have been observed on previous surveys of FU19.
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    Porcupine Bank Nephrops Grounds (FU16) 2014 UWTV Survey Report and catch options for 2015

    Doyle, J.; Lordan, C.; O'Cuaig, M.; Hannify, O.; Murphy, Á.; Sheridan, M.; Vila, Y. (Marine Institute, 2014-10)
    This report provides the results of the third 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 67 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 2014, adjusted for edge effect, was 0.10 burrows/m². The final krigged abundance estimate was 722 million burrows with a relative standard error of 3% and an estimated stock area of 7,108km2. The abundance estimate was 6% lower than in 2013. Landings options at various different fishing mortalities were calculated in line with the recommendations of WKNEPH 2013. Fishing at Fmsy in 2015 implies catches of 1,850 t which close to the 2014 catch limit. This is because of an increase in average mean weight of the landings. The three species of sea-pen; Virgularia mirabilis, Funiculina quadrangularis and Pennatula phosphorea, were all observed during the survey. Trawl marks were also observed on over half of the stations surveyed.
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    The “Smalls” Nephrops Grounds (FU22) 2014 UWTV Survey Report and catch options for 2015

    Lordan, C.; Doyle, J.; Fitzgerald, R.; O'Connor, S.; Blaszkowski, M.; Simpson, S. (Marine Institute, 2014-10)
    This report provides the main results and findings of the ninth annual underwater television survey on the ‘Smalls grounds’ ICES assessment area; Functional Unit 22. The survey was multi-disciplinary in nature collecting UWTV, CTD and other ecosystem data. A total of 52 stations UWTV stations were carried out over an isometric grid at 4.5nmi or 8.3km intervals. The krigged burrow abundance estimate for the Smalls ground increased by 22% relative to 2013 and was the highest in the 9 year time series. The final abundance estimate was 1,622 million with a CV of 8% which is well below the upper limit of 20% recommended by SGNEPS 2012. Using the 2014 estimate of abundance and recent mean weight and discard data would imply total catches at Fmsy in 2015 of 3,797t. This implies landings of 3,409 tonnes. Temperature on the seabed varied by 2oC over the Nephrops ground with coldest values around 9.4oC in the deepest part of the area. Only one species of sea pen Virgilaria mirabilis was recorded as present at 46% of the stations surveyed. Trawl marks were observed at 28% of the stations surveyed.
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    The Labadie, Jones and Cockburn Banks Nephrops Grounds (FU2021) 2014 UWTV Survey Report and catch options for 2015

    Doyle, J.; Lordan, C.; Hehir, I.; Fitzgerald, R.; O'Connor, S.; Keith, M.; Sheridan, M. (Marine Institute, 2014-10)
    This report provides the main results of the 2014 underwater television survey on the ‘Labadie, Jones and Cockburn Banks’ ICES assessment area; Functional Unit 20-21. Some exploratory UWTV stations were carried out in 2006 and 2012. In 2013 ~60% of the ground was surveyed. This was the first survey to achieve full coverage of the newly defined area. The 2014 survey was multi-disciplinary in nature collecting UWTV, CTD and other ecosystem data. A randomised isometric grid design was employed with 98 UWTV stations at 6.0 nmi intervals. The mean burrow density was 0.19 burrows/m2 compared with 0.16 burrows/m2 in 2013. The 2014 geostatistical abundance estimate was 2.1±0.1 billion a 26% increase on the extrapolated abundance for 2013. Highest densities were general observed towards the middle of the ground, but there were also high densities observed close to boundaries. Using the 2014 abundance and recent fisheries data it is possible to estimate harvest ratios consistent with various landings options. These can be used by ICES to provide catch options for 2015. The occurrence of sea-pens and trawl marks on the UWTV footage and processed CTD is also presented.
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