• 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.
    • 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
    • Porcupine Bank Nephrops Grounds (FU16) 2017 UWTV Survey Report and catch options for 2018

      Lordan, C.; Doyle, J.; Butler, R.; Sugrue, S.; Allsop, C.; O’Connor, S.; Vacherot, J.P. (Marine Institute, 2017)
      This report provides the results of the fifth 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 63 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 2017, adjusted for edge effect, was 0.12 burrows/m². The final krigged abundance estimate was 850 million burrows with a relative standard error of 5% and an estimated stock area of 7,134 km2. The 2017 abundance estimate was 11% lower than in 2016. Using the 2017 estimate of abundance and updated stock data implies catch of 2,734 tonnes and landings of 2,734 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 43% of the stations surveyed.
    • The “Smalls” Nephrops Grounds (FU22) 2012 UWTV Survey Report and catch options for 2013

      Doyle, Jennifer; Lordan, Colm; Hehir, Imelda; Fee, Dermot; O'Connor, Sean; Browne, Patricia; Casserly, Joanne (Marine Institute, 2012)
      This report provides the main results and findings of the seventh annual underwater television on the ‘Smalls grounds’ ICES assessment area; Functional Unit 22. The survey was multi-disciplinary in nature collecting UWTV, fishing, CTD and other ecosystem data. An analysis of the precision, accuracy and sampling intensity trade-offs showed that sampling intensity could be reduced without compromising the utility of the survey. Consequently, sampling intensity was reduced this year from around 100 stations in the past to 47 stations this year. The krigged burrow abundance estimate for Smalls ground has increased by 17% relative to 2011and was the second highest in the 7 year history of the survey. Abundance estimates have been fairly stable over the time series. The 2012 randomised isometric grid design result in a CV (or relative standard error) of 8%. Well below the upper limit of 20% recommended by SGNEPS 2012. Nephrops accounted for 22% of the catch weight from 6 beam trawl tows. Length-weight, maturity and by-catch data are all reported.
    • The “Smalls” Nephrops Grounds (FU22) 2013 UWTV Survey Report and catch options for 2014

      Doyle, J.; Lordan, C.; Hehir, I.; Fitzgerald, R.; O’Connor, S.; O’Donovan, S.; Salaun, M. (Marine Institute, 2013)
      This report provides the main results and findings of the eighth 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. The sampling intensity was reduced this year from around 100 stations in the past to 51 stations this year. A randomised isometric grid design was employed with UWTV stations at 4.5nmi or 8.3km intervals. Previously a 3.0 nmi square grid was used. The krigged burrow abundance estimate for the Smalls ground has decreased by 19% relative to 2012 and was the fourth highest in the 8 year history of the survey. Abundance estimates have been fairly stable over the time series. The 2013 randomised isometric grid design result in a CV (or relative standard error) of 7% which is 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 2014 implies a total catch option at Fmsy (=Fmax) of 2,937 tonnes which results in landings of no more than 2,674 tonnes.
    • 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.
    • The “Smalls” Nephrops Grounds (FU22) 2015 UWTV Survey Report and catch options for 2016

      Lordan, C.; Doyle, J.; Fitzgerald, R.; O’Connor, S.; Blaszkowski, M.; Butler, R. (Marine Institute, 2015)
      This report provides the main results and findings of the tenth 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 33 UWTV stations were surveyed successfully (good quality video footage) carried out over an isometric grid at 4.5nmi or 8.3km intervals. Of the planned stations 17% (7) could not be completed due to very poor or nil visibility conditions encountered at seabed. For these stations density estimates were filled-in using and average of historic values within 2nmi. The resulting krigged burrow abundance estimate for the Smalls ground decreased by 16% relative to 2014. The final abundance estimate was 1,363 million. The precision, with a CV of 7%, was well below the upper limit of 20% recommended by SGNEPS 2012. Using the 2015 estimate of abundance and updated stock data implies catch of 3,027 tonnes and landings of 2634 tonnes in 2016 fishing at Fmsy (assuming that all catch is landed). Only one species of sea pen Virgilaria mirabilis was recorded as present at the stations surveyed. Trawl marks were observed at 12% of the stations surveyed.
    • The “Smalls” Nephrops Grounds (FU22) 2017 UWTV Survey Report and catch options for 2018

      O’Brien, S.; Blaszkowski, M.; Butler, R.; Fee, D.; Hernon, P.; Santana, C.; Lordan, C.; Doyle, J. (Marine Institute, 2017)
      This report provides the main results and findings of the twelfth 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 40 UWTV stations were surveyed successfully (good quality video footage) carried out over an isometric grid at 4.5nmi or 8.3km intervals. The precision, with a CV of 5%, was well below the upper limit of 20% recommended by SGNEPS 2012. The 2017 abundance estimate was 16% higher than in 2016 and at 1600 million is above the new MSY Btrigger (990 million). Using the 2017 estimate of abundance and updated stock data implies catch of 4,332 tonnes and landings of 3,784 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). Only one species of sea-pen Virgilaria mirabilis was recorded as present at the stations surveyed. Trawl marks were observed at 59% of the stations surveyed. Ten beam trawl tows were carried out providing important data on the benthic communities and size structure of the Nephrops population.
    • The “Smalls” Nephrops Grounds (FU22) 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 and findings of the thirteenth 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 42 UWTV stations were surveyed successfully (good quality video footage), carried out over an isometric grid at 4.5nmi or 8.3km intervals. The precision, with a CV of 9%, was well below the upper limit of 20% recommended by SGNEPS (ICES, 2012). The 2018 abundance estimate was 45% lower than in 2017 and at 876 million is below the MSY Btrigger reference point (990 million). Using the 2018 estimate of abundance and updated stock data implies catch of 2,084 tonnes and landings of 1,780 tonnes in 2019 when the MSY approach is applied (assuming that discard rates and fishery selection patterns do not change from the average of 2015–2017). Two species of sea pens were recorded as present at the stations surveyed: Virgularia mirabilis and Pennatula phosphorea. Trawl marks were observed at 55% of the stations surveyed. Nine beam trawl tows were carried out, providing important data on the benthic communities and size structure of the Nephrops population.
    • Western Irish Sea Nephrops (FU15) 2007 UWTV Survey Report

      Lordan, Colm; Doyle, Jennifer; Briggs, Richard (Marine Institute & Agri-Food and Biosciences Institute, 2008)
      The UWTV survey has been conducted on the western Irish Sea for a time series of 5 years. This report details the results of the surveys to date. The paper identifies a number of issues critical to the calculation of absolute abundance indices from the surveys and concludes that it is premature to have catch advice based directly on the survey although currently there is no serious concern regarding stock status on the western Irish Sea since burrow counts are still high.
    • Western Irish Sea Nephrops (FU15) 2008 UWTV Survey Report

      Lordan, Colm; Doyle, Jennifer; Briggs, Richard (Marine Institute & Agri-Food and Biosciences Institute, 2009-05)
      This survey is carried out in co-operation with Marine Institute (Ireland) and AFBI (Northern Ireland) and is in its sixth year. A revision of the count data for the early years 2003 and 2004 is also presented where the initial high burrow estimates were checked and a drift in burrow identification was detected as detailed in SGNEPS 2009.
    • Western Irish Sea Nephrops (FU15) 2010 UWTV Survey Report

      Lordan, Colm; Doyle, Jennifer; Briggs, Richard (Marine Institute & Agri-Food and Biosciences Institute, 2011-05)
      Since 2003 a joint UWTV survey has been carried out by the Marine Institute(Ireland) and AFBI (Northern Ireland). For the first time in 2009 this survey was used to develop catch options for the stock using a bias corrected survey estimate as an absolute measure of stock size and recent discard rates and mean weight to forecast catch (ICES, 2009a). This report details the results of the 2010 survey for the western Irish Sea Nephrops stock. We also update the catch option table using the most recent survey estimate.
    • Western Irish Sea Nephrops Grounds (FU 15) 2009 UWTV Survey Report

      Lordan, C; Doyle, J; Briggs, R (Marine Institute, 2009-09)
      Since 2003 a joint UWTV survey has been carried out by the Marine Institute (Ireland) and AFBI (Northern Ireland). In 2009 this survey was used to develop catch options for the stock using a bias corrected survey estimate as an absolute measure of stock size and recent discard rates and mean weight to forecast catch (ICES, 2009a). This report details the results of the 2009 survey for the western Irish Sea Nephrops stock. We also update the catch option table using the most recent survey estimate.
    • Western Irish Sea Nephrops Grounds (FU15) 2011 UWTV Survey Report

      Lordan, Colm; Service, Matthew; Doyle, Jennifer; Fitzgerald, Ross (Marine Institute & Agri-Food and Biosciences Institute, 2011)
      This is the ninth in a time series of UWTV surveys in the western Irish Sea carried out jointly by the Marine Institute, Ireland and the Agri-Food and Biosciences Institute (AFBI), Northern 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.
    • Western Irish Sea Nephrops Grounds (FU15) 2012 UWTV Survey Report

      Doyle, J.; Lordan, C.; Fitzgerald, R.; Strong, J.; Service, M. (Marine Institute & Agri-Food and Biosciences Institute, 2013)
      This report provides the main results and findings of the tenth annual underwater television on the ‘Irish sea west Nephrops grounds’ ICES assessment area; Functional Unit 15. The survey was multi-disciplinary in nature collecting UWTV, CTD and other ecosystem data. An analysis of the precision, accuracy and sampling intensity trade-offs showed that sampling intensity could be reduced without significantly reducing the precision and accuracy of the survey. Consequently, sampling intensity was reduced this year from ~150 stations in a 3.5 nautical mile grid to 99 stations (4.5nmi grid). Full coverage of the grid was achieved. The krigged burrow abundance estimate for the Irish Sea ground increased slightly (+3% relative to 2011). Abundance estimates have been fairly very stable over the time series. The 2012 randomised isometric grid design resulted in a CV (or relative standard error) of 3% which is in line with CVs observed previously and well below the upper limit of 20% recommended by SGNEPS 2012.
    • Western Irish Sea Nephrops Grounds (FU15) 2013 UWTV Survey Report and catch options for 2014

      Doyle, J.; Lordan, C.; Ligas, A.; Brown, V.; Leocadio, A.; McCausland, I.; McCorriston, P.; Service, M.; Stewart, P.; Schön, P.J. (Marine Institute & Agri-Food and Biosciences Institute, 2013)
      This report provides the main results and findings of the eleventh 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 2013 design consisted of a randomised isometric grid of 80 stations at 5 nautical mile intervals out over the full known extent the stock. The resulting krigged burrow abundance estimate was 4.3 billion burrows. This was a 16% decrease relative to 2012. The spatial distribution shows higher abundance in the south of the area and a larger decline in abundance is apparent in the North. Overall densities remain high and abundance remains relatively stable, well above MSY Btrigger. Reducing the number of stations in 2013 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 2014 implies a total catch option at Fmsy (=Fmax) of 9,914 tonnes which results in landings of no more than 8,244 tonnes. The only sea-pen species observed in 2013 was Virgularia mirabilis and the frequency of occurrence was lower than in 2012. Trawl marks were noted at 43% of the UWTV stations.
    • 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.