• Celtic Sea Nephrops Grounds 2007 UWTV Survey Report

      Lordan, Colm; Doyle, Jennifer (Marine Institute, 2008-05)
      This is the second in a time series of UWTV surveys on the ‘Smalls grounds’. The 2006 survey covered the distinct mud patches of the Smalls Grounds and also indicator stations on the Labadie Bank, Nymphe Bank and Seven Heads, whereas the survey 2007 covered the Smalls Grounds only due to poor weather. This report details the results of the surveys on the Smalls Grounds to date.
    • Celtic Sea Nephrops Grounds 2008 UWTV Survey Report

      Lordan, Colm; Doyle, Jennifer (Marine Institute, 2009-05)
      This is the third in a time series of UWTV surveys on the ‘Smalls grounds’. The 2006 survey covered the distinct mud patches of the Smalls Grounds and also indicator stations on the Labadie Bank, Nymphe Bank and Seven Heads, whereas the 2007 and 2008 survey covered the Smalls Grounds only due to poor weather and time contraints. This report details the results of the surveys on the Smalls Grounds only to date.
    • Celtic Sea Nephrops Grounds 2009 UWTV Survey Report

      Lordan, C; Doyle, J (Marine Institute, 2010-05)
      This is the fourth in a time series of UWTV surveys on the ‘Smalls grounds’. The 2006 survey covered the distinct mud patches of the Smalls Grounds and also indicator stations on the Labadie Bank, Nymphe Bank and Seven Heads, whereas the 2007 to 2009 survey covered the Smalls grounds only due to poor weather and time constraints. This report details the results of the 2009 survey for the Smalls ground Nephrops stock.
    • Celtic Sea Nephrops Grounds 2010 UWTV Survey Report

      Lordan, Colm; Doyle, Jennifer (Marine Institute, 2011-04)
      This is the fifth in a time series of UWTV surveys on the ‘Smalls grounds’. The 2006 survey covered the distinct mud patches of the Smalls Grounds and also indicator stations on the Labadie Bank, Nymphe Bank and Seven Heads, whereas the 2007 to 2010 survey covered the Smalls grounds only due to poor weather and time contraints. This report details the results of the 2010 survey for the Smalls ground Nephrops stock.
    • Celtic Sea Nephrops Grounds 2011 UWTV Survey Report

      Doyle, Jennifer; Lordan, Colm; Fitzgerald, Ross; O’Connor, Sean; Fee, Dermot; Nolan, Cormac; Hayes, Joan (Marine Institute, 2011)
      The prawn (Nephrops norvegicus) are common in the Celtic Sea occurring in geographically distinct sandy/muddy areas were the sediment is suitable for them to construct their burrows. The Celtic Sea area (Functional Units 19-22) supports a large multi-national targeted Nephrops fishery mainly using otter trawls and yielding landings in the region of ~6,000 t annually over the last decade (ICES, 2011). Nephrops spend a great deal of time in their burrows and their emergence behaviour is influenced many factors; time of year, light intensity and tidal strength. Underwater television surveys and assessment methodologies have been developed to provide a fishery independent estimate of stock size, exploitation status and catch advice (ICES, 2009 & 2011).This is the sixth in a time series of UWTV surveys in the Celtic Sea carried out by the Marine Institute, Ireland. The 2011 survey was multi disciplinary in nature and this report details the final UWTV results of the 2011 survey and also documents other data collected during the survey.
    • FU19 Nephrops Grounds 2011 UWTV Survey Report

      Lordan, Colm; Doyle, Jennifer; Fitzgerald, Ross (Marine Institute, 2011)
      This report provides the main results and findings of the second underwater television survey of the various Nephrops grounds in Functional Unit 19. The survey was multi-disciplinary in nature collecting UWTV, CTD and other ecosystem data. In total 35 UWTV stations were successfully completed on the following Nephrops grounds: Bantry Bay, Galley, Cork Channels and Helvick. Raised abundance estimates for these grounds are provided for the first time based on improved knowledge of the boundaries of those areas.
    • FU19 Nephrops Grounds 2013 UWTV Survey and catch options for 2014

      Lordan, C.; Doyle, J.; Hehir, I.; O’Sullivan, D.; Allsop, C.; O’Connor, S.; Blaszkowski, M.; Butler, R.; Burke, C.; Stewart, P. (Marine Institute, 2013)
      This report provides the main results and findings of the fourth underwater television survey of the various Nephrops grounds in Functional Unit 19. The survey was multi-disciplinary in nature collecting UWTV, CTD, multi-beam and other ecosystem data. In 2013 a total 40 UWTV stations were successfully completed. Adjusted burrow density estimates varied considerably across the different grounds. The 2013 raised abundance estimate of 397 million burrows is a 20% decrease from the 2012 estimate. Taking into account the uncertainty (CV of 17%) this is not significantly different from abundance estimates in 2011 or 2012. Using the 2013 abundance and recent mean weight and discard implies 2014 total catch advice fishing at Fmsy (=F35%spr) of 618 tonnes which results in landings of no more than 521 tonnes.
    • 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.
    • FU19 Nephrops Grounds 2015 UWTV Survey and catch options for 2016

      Lordan, C.; Doyle, J.; Fitzgerald, R.; O’Connor, S.; Blaszkowski, M.; Stokes, D.; Ni Chonchuir, G.; Gallagher, J.; Butler, R.; Sheridan, M.; Simpson, S. (Marine Institute, 2015)
      This report provides the main results of the sixth 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 2015 a total 39 UWTV stations were successfully completed. The mean density estimates varied considerably across the different patches. The 2015 raised abundance estimate of 482 million burrows was a 24% decrease from the 2014 estimate. Taking into account the uncertainty (CV of 13%) there is no significant difference in abundance estimates since 2011. Using the 2015 abundance estimate and recent mean weights and discard parameters would imply total catches of 793 t fishing at Fmsy in 2016. This stock will be subject to the landing obligation in 2016 and the calculation of catch options assume that all catches will be landed in 2016. The catch can be partitioned into landings of 543 t and discards of 250 t. The estimated discards rates in FU19 are relatively high and impact of this on the catch options is discussed. One species of sea pen was observed; Virgularia mirabilis which has been observed on previous surveys of FU19.
    • FU19 Nephrops Grounds 2017 UWTV Survey and catch options for 2018

      Doyle, J.; Fitzgerald, R.; O’Brien, S.; Ryan, G.; McGeady, R.; Lordan, C. (Marine Institute, 2017)
      This report provides the main results of the eighth 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 2017 a total 41 UWTV stations were successfully completed. The mean density estimates varied considerably across the different patches. The 2017 raised abundance estimate was a 25% increase from the 2016 estimate and at 499 million burrows is above the MSY Btrigger (430 million). Using the 2017 estimate of abundance and updated stock data implies catch of 1,192 tonnes and landings of 889 tonnes in 2018 when MSY approach is applied (assuming that discard rates and fishery selection patterns do not change from the average of 2014–2016). Two species of sea pen were observed; Virgularia mirabilis and Pennatula phosphorea which have been observed on previous surveys of FU19. Trawl marks were observed at 10% of the stations surveyed.
    • FU19 Nephrops grounds 2018 UWTV survey report and catch scenarios for 2019.

      Aristegui, M.; O’Brien, S.; Blaszkowski, M.; O’Connor, S.; Fitzgerald, R.; Doyle, J. (Marine Institute, 2018)
      This report provides the main results of the ninth underwater television survey of the various Nephrops patches in Functional Unit 19. The survey was multidisciplinary in nature collecting UWTV, multi-beam and other ecosystem data. In 2018 a total 42 UWTV stations were successfully completed. The mean density estimates varied considerably across the different patches. The 2018 raised abundance estimate was a 65% decrease from the 2017 estimate and at 176 million burrows is below the MSY Btrigger (430 million). Using the 2018 estimate of abundance and updated stock data implies catch of 173 tonnes and landings of 130 tonnes in 2018 when MSY approach is applied (assuming that discard rates and fishery selection patterns do not change from the average of 2015–2017). One species of sea pen was observed; Virgularia mirabilis, which has been observed on previous surveys of FU19. Trawl marks were observed at 36% of the stations surveyed.
    • Labadie, Jones and Cockburn Banks (FU20-21) 2013 UWTV Survey Report

      Doyle, J.; Lordan, C.; Hehir, I.; O’Sullivan, D.; O’Connor, S.; Blaszkowski, M.; Stewart, P. (Marine Institute, 2013)
      This report provides the main results of the 2013 underwater television survey on the ‘Labadie, Jones and Cockburn Banks’ ICES assessment area; Functional Unit 20-21. Some exploratory stations were carried out in 2006 and 2012. The survey was multi-disciplinary in nature collecting UWTV, CTD, Multibeam and other ecosystem data. A randomised isometric grid design was employed with UWTV stations at 6.0 nmi intervals. Due to weather and technical downtime only 58 out of the 95 planned stations were successfully completed. The adjusted mean density for 2013 was 0.18/m2 which can be classified as “low density”. Scientific knowledge of the heterogeneous habitat and spatial distribution of the Nephrops population in this area is developing. Survey design and burrow identification are particularly difficult in this area due to factors discussed. The occurrence of sea-pens and trawl marks on the UWTV footage is also presented.
    • The Labadie, Jones and Cockburn Banks Nephrops Grounds (FU20-21) 2018 UWTV Survey Report and catch scenarios for 2019.

      Doyle, J.; Aristegui, M.; Hannify, O.; White, J.; Fee, D.; McCorriston, P. (Marine Institute, 2018)
      This report provides the main results of the 2018 underwater television survey on the ‘Labadie, Jones and Cockburn Banks’ ICES assessment area; Functional Unit 20-21. This was the fifth survey to achieve full coverage of the full area. The 2018 survey was multidisciplinary in nature collecting UWTV, and other ecosystem data. A total of 96 UWTV stations were completed at 6 nm intervals over a randomised isometric grid design. The mean burrow density was 0.27 burrows/m2 compared with 0.44 burrows/m2 in 2017. The 2018 geostatistical abundance estimate was 2.7±0.006 billion, a 39% decrease on the abundance for 2017, with a CV of 4% which is well below the upper limit of 20% recommended by SGNEPS 2012. High densities were observed throughout the ground, and also close to boundaries. Using the 2018 abundance estimate and updated stock data implies catch of 5,320 t and landings of 4,325 t in 2019 when MSY approach is applied (assuming that discard rates and fishery selection patterns do not change from the average of 2015–2017). One species of sea-pen (Virgularia mirabilis) were recorded as present at the stations surveyed. Trawl marks were observed at 33% of the stations surveyed.
    • 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.
    • The Labadie, Jones and Cockburn Banks Nephrops Grounds (FU2021) 2015 UWTV Survey Report and catch options for 2016

      Lordan, C.; Doyle, J.; Fitzgerald, R.; O’Connor, S.; Blaszkowski, M.; Stokes, D.; Ni Chonchuir, G.; Gallagher, J.; Butler, R.; Sheridan, M.; Simpson, S.; Blandon, A.; Meakins, B. (Marine Institute, 2015)
      This report provides the main results of the 2015 underwater television survey on the ‘Labadie, Jones and Cockburn Banks’ ICES assessment area; Functional Unit 20-21. This was the second survey to achieve full coverage of the full area. The 2015 survey was multidisciplinary in nature collecting UWTV, CTD and other ecosystem data. A total of 96 UWTV stations were completed at 6 nmi intervals over a randomised isometric grid design. The mean burrow density was 0.20 burrows/m2 compared with 0.19 burrows/m2 in 2014. The 2015 geostatistical abundance estimate was 2.0±0.02 billion a 2% decrease on the abundance for 2014 with a CV of 3% which is well below the upper limit of 20% recommended by SGNEPS 2012. Highest densities were general observed towards the north and southwest of the ground, and there were also high densities observed close to boundaries. Using the 2015 abundance estimate and updated stock data implies catch of 3045 tonnes and landings of 2225 tonnes. Only one species of sea pen Virgilaria mirabilis was recorded as present at the stations surveyed. Trawl marks were observed at 30% of the stations surveyed.
    • The Labadie, Jones and Cockburn Banks Nephrops Grounds (FU2021) 2017 UWTV Survey Report and catch options for 2018

      Doyle, J.; Fitzgerald, R.; O’Brien, S.; Ryan, G.; McGeady, R.; Lordan, C. (Marine Institute, 2017)
      This report provides the main results of the 2017 underwater television survey on the ‘Labadie, Jones and Cockburn Banks’ ICES assessment area; Functional Unit 20-21. This was the fourth survey to achieve full coverage of the full area. The 2017 survey was multi-disciplinary in nature collecting UWTV, CTD and other ecosystem data. A total of 86 UWTV stations were completed at 6 nmi intervals over a randomised isometric grid design. The mean burrow density was 0.44 burrows/m2 compared with 0.18 burrows/m2 in 2016. The 2017 geostatistical abundance estimate was 4.4±0.01 billion a 236% increase on the abundance for 2016 with a CV of 4% which is well below the upper limit of 20% recommended by SGNEPS 2012. Highest densities were generally observed throughout the ground, and there were also high densities observed close to boundaries. Using the 2017 abundance estimate and updated stock data implies catch of 8,673 tonnes and landings of 6,553 tonnes in 2018 when MSY approach is applied (assuming that discard rates and fishery selection patterns do not change from the average of 2014–2016). One species of sea-pen were recorded as present at the stations surveyed Virgilaria mirabilis. Trawl marks were observed at 32% of the stations surveyed.
    • Porcupine Bank Nephrops Grounds (FU16) 2018 UWTV Survey Report and catch scenarios for 2019

      Doyle, J.; O'Brien, S.; Ryan, G.; Galligan, S.; Hernon, P.; Aristegui, M.; Vacherot, J.P.; Lordan, C. (Marine Institute, 2018)
      This report provides the results of the sixth 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 69 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 2018, adjusted for edge effect, was 0.16 burrows/m². The final krigged abundance estimate was 1117 million burrows with a relative standard error of 4% and an estimated stock area of 7,130 km2. The 2018 abundance estimate was 31% higher than in 2017. Using the 2018 estimate of abundance and updated stock data implies catch of 2,645 tonnes and landings of 2,645 tonnes in 2019 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 33% of the stations surveyed.
    • Porcupine Bank Nephrops Grounds (FU16) 2012 UWTV Survey Report and catch options for 2013

      Lordan, Colm; Doyle, Jennifer; Dobby, Helen; Hehir, Imelda; Fee, Dermot; Allsop, Chris; O'Neill, Ross (Marine Institute, 2012)
      This report provides the results of the first 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. The UWTV results and a scientific basis for survey based catch advice in 2013 are presented. In total 47 UWTV stations were successfully completed. The mean burrow density was 0.19 burrows/m² (empirical 95% confidence intervals are from 0.17-0.21). The final krigged abundance estimate was 992 million burrows with a relative standard error of 5% and an estimated stock area of 7,100km2. This abundance estimate can be considered as a conservative estimate given that the spatial coverage of the southern part of the ground was not complete. A correction factor of 1.26 is proposed based on expert judgments of burrow size and potential detection and identification biases. A yield and spawner per recruit analysis was used to estimate a harvest rate of 5.0% for the combined sex F0.1 and other F reference points. This harvest rate is low compared to other FUs and can be considered very conservative. Applying this harvest rate to the abundance observed in the survey and using a mean weight in the landings of 45.0g implies landings in 2013 of 1,770 t. The results here could form the basis of the catch advice for 2013.
    • Porcupine Bank Nephrops Grounds (FU16) 2013 UWTV Survey Report and catch options for 2014

      Lordan, C.; Doyle, J.; O'Connor, S.; Hehir, I.; Fitzgerald, R.; Blaszkowski, M.; O'Sullivan, D.; O’Donovan, S.; Salaun, M.; Stewart4, P. (Marine Institute, 2013)
      This report provides the results of the second 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 68 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 2013, adjusted for edge effect, was 0.106 burrows/m². The final krigged abundance estimate was 768 million burrows with a relative standard error of 4% and an estimated stock area of 7,100km2. The abundance estimate was 2% lower than in 2012. Landings options at various different fishing mortalities were calculated in line with the recommendations of WKNEPH 2013. Fishing at Fmsy in 2014 implies a slight increase in the TAC from 1,800 t to 1,850 t. This increase is mainly due to an increase in average mean weight of the landings. The three species of sea-pen found on muddy habitat in Irish waters are 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.
    • 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.