• Aran, Galway Bay and Slyne Head Nephrops Grounds (FU17) 2012 UWTV Survey Report and catch options for 2013

      Lordan, Colm; Doyle, Jennifer; Hehir, Imelda; Fee, Dermot; Allsop, Chris; O'Neill, Ross (Marine Institute, 2012)
      This report provides the main results and findings of the eleventh 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. The sampling intensity was reduced this year from around 75 stations in the past to 31 on the Aran grounds. A randomised isometric grid design was employed with UWTV stations at 3.5nmi or 6.5km intervals. Previously a 2.25 nmi square grid was used. The kigged burrow abundance estimate declined by 34% relative to 2011 with a CV (or relative standard error) of 5 %. Abundance estimates have fluctuated considerably over the time series but the 2012 abundance is the lowest in the 11 year history of the survey. Four UWTV stations were carried out on the Galway Bay and 3 on the Slyne Head Nephrops grounds. Raised abundance estimates for Galway Bay and Slyne Head are provided based on improved knowledge of the boundaries of those areas. Nephrops accounted for 85% of the benthic catch by weight from 4 beam trawl tows. The observed length frequency and maturity of female Nephops caught was similar to previous years. Various further investigations needed before the next ICES benchmark are discussed.
    • Aran, Galway Bay and Slyne Head Nephrops Grounds 2007 UWTV Survey Report

      Lordan, Colm; Doyle, Jennifer (Marine Institute, 2008)
      In 2007 the sixth in a series of annual UWTV survey was complete and the results of that survey together with a synthesis and analysis of the results. A geostatistical analysis indicates that burrow densities and abundances have fluctuated considerably in space and time. The highest densities occurred in 2004 and the lowest densities in the 2006.The 2007 survey shows an increase in burrow density. Using the survey directly for assessment and management is not yet possible. However, there appears to a negative relationship between abundance and landings in the autumn and a positive relationship between observed densities and landings the following spring. The relationship between abundance and landings is not as clear. There is no serious concern about the stock given the recent survey abundance.
    • Aran, Galway Bay and Slyne Head Nephrops Grounds 2008 UWTV Survey Report

      Lordan, Colm; Doyle, Jennifer (Marine Institute, 2009-05)
      In 2008 the seventh in a series of annual UWTV survey was complete and the results of that survey together with a synthesis and analysis of the results is presented. A geostatistical analysis indicates that burrow densities and abundances have fluctuated considerably in space and time. The highest densities occurred in 2004 and the lowest densities in 2008.The 2008 survey shows a decrease in burrow density to the lowest observed. Using the survey directly for assessment and management has been discussed at WKNEPHTV (2007) and at SGNEP (2009).This stock was a focus at the benchmark workshop on Nephrops assessment held in Aberdeen WKNEPH, (2009). There appears to a negative relationship between abundance and landings in the autumn and a positive relationship between observed densities and landings the following spring. There is some concern about the stock given the most recent survey abundance observed to date. The time series is short and to date survey estimates have fluctuated across a large dynamic range.
    • Aran, Galway Bay and Slyne Head Nephrops Grounds 2010 UWTV Survey Report

      Lordan, Colm; Doyle, Jennifer (Marine Institute, 2011-05)
      This is the ninth data point in a time series of UWTV surveys on the ‘Aran grounds’. The survey covers three distinct mud patches; the Aran Ground, Galway Bay and Slyne Head. These have approximate areas of 940, 41 and 26 km2 respectively. 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 and updates the catch option table using the most recent survey estimate.
    • Aran, Galway Bay and Slyne Head Nephrops Grounds 2011 UWTV Survey Report

      Lordan, Colm; Doyle, Jennifer; Bunn, Robert; Fee, Dermot; Allsop, Chris (Marine Institute, 2011-10)
      This report provides the main results and findings of the tenth annual underwater television on the ‘Aran grounds’ ICES assessment area; Functional Unit 17. The survey was multi-disciplinary in nature collecting UWTV, fishing, CTD and other ecosystem data. In total 76, 10 and 7 UWTV stations were successfully completed on the Aran, Galway Bay and Slyne Head Nephrops Grounds. The observed abundance estimate for the main Aran ground has declined by 23% relative to 2010. Abundance estimates have fluctuated over the time series. The 2011 abundance is the third lowest in the 10 year history of the survey. This is not a cause for immediate concern about the stocks sustainability. Raised abundance estimates for Galway Bay and Slyne Head are provided for the first time based on improved knowledge of the boundaries of those areas. Nephrops accounted for 26% of the catch weight from 10 beam trawl tows. The observed length frequency and maturity of female Nephops caught was similar to previous years. Various further investigations needed before the next ICES benchmark are discussed.
    • 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 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 2021 UWTV Survey Report and catch scenarios for 2022

      Doyle, Jennifer; Ryan, G; Aristegui, M.; Fitzgerald, Ross; Tully, D.; O’Brien, S.; White, Jonathan; Sullivan, M.; Lynch, Deirdre; McAuliffe, M (Marine Institute, 2021)
      This report provides the main results of the twelfth underwater television survey of the various Nephrops patches in Functional Unit 19. The survey was multi-disciplinary in nature collecting UWTV and other ecosystem data. In 2021 a total 42 UWTV stations were successfully completed. The mean density estimates varied considerably across the different patches. The 2021 raised abundance estimate was a 16% decrease from the 2020 estimate and at 270 million burrows is below the MSY Btrigger reference point (430 million). Using the 2021 estimate of abundance and updated stock data implies catch in 2022 that correspond to the F ranges in the EU multi annual plan for Western Waters are between 363 and 407 tonnes (assuming that discard rates and fishery selection patterns do not change from the average of 2018–2020). One species of sea pen were observed; Virgularia mirabilis which has been observed on previous surveys of FU19. Trawl marks were observed at 19% of the stations surveyed.
    • The Labadie, Jones and Cockburn Banks Nephrops Grounds (FU2021) 2021 UWTV Survey Report and catch scenarios for 2022.

      Doyle, Jennifer; Ryan, G.; Aristegui, M.; Fitzgerald, Ross; Tully, D.; O'Brien, S.; White, Jonathan; Sullivan, M.; Lynch, Deirdre; McAuliffe, M (Marine Institute, 2021)
      This report provides the main results of the 2021 underwater television survey on the ‘Labadie, Jones and Cockburn Banks’ ICES assessment area; Functional Unit 2021. The 2021 survey was multi-disciplinary in nature collecting UWTV and other ecosystem data. A total of 97 UWTV stations were completed at 6 nm intervals over a randomised isometric grid design. The mean burrow density was 0.12 burrows/m2 compared with 0.102 burrows/m2 in 2020. The 2021 geostatistical abundance estimate was 1202 million, a 18% increase on the abundance from 2020, with a CV of 5%, which is well below the upper limit of 20% recommended by SGNEPS 2012. Low to medium densities were observed throughout the ground. Using the 2021 estimate of abundance and updated stock data implies catch in 2022 that correspond to the ICES MSY approach of 1978 tonnes assuming that discard rates and fishery selection patterns do not change from the average of 2018–2020. One species of sea-pen (Virgularia mirabilis) were recorded as present at the stations surveyed. Trawl marks were observed at 21% 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) 2021 UWTV Survey Report and catch scenarios for 2022

      Aristegui, M.; Blaszkowski, M.; Doyle, Jennifer; O'Brien, S.; Hehir, Imelda; Bentley, K.; Fitzgerald, Ross (Marine Institute, 2021)
      This report provides the results of the ninth underwater television on the ‘Porcupine Bank Nephrops grounds’ ICES assessment area; Functional Unit 16. The survey was multi-disciplinary in nature collecting UWTV and other ecosystem data. In total 71 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 2021, adjusted for edge effect, was 0.14 burrows/m². The final krigged abundance estimate was 1018 million burrows with a CV of 5% and an estimated stock area of 7,130 km2. The 2021 abundance estimate was 19% lower than in 2020. Using the 2021 estimate of abundance and updated stock data imply that catches in 2022 should be no more than 2804 tonnes, according to the EU MAP and ICES MSY approach (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 38% 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) 2021 UWTV Survey Report and catch scenarios for 2022

      Aristegui, M.; Fitzgerald, Ross; Lynch, Deirdre; White, Jonathan; Doyle, Jennifer; McAuliffe, M (Marine Institute, 2021)
      This report provides the main results and findings of the sixteenth annual underwater television survey on the ‘Smalls grounds’ ICES assessment area; Functional Unit 22. The survey was multi-disciplinary in nature collecting UWTV and other ecosystem data. A total of 42 UWTV stations were surveyed successfully (high quality image data), carried out over an isometric grid at 4.5nmi or 8.3km intervals. The precision, with a CV of 7%, was well below the upper limit of 20% recommended by SGNEPS (ICES, 2012). The 2021 abundance estimate was 13% lower than in 2020 and at 656 million is below the MSY Btrigger reference point (990 million). Using the 2021 estimate of abundance and updated stock data implies catch in 2022 that correspond to the ICES MSY approach of 1257 tonnes assuming that discard rates and fishery selection patterns do not change from the average of 2018–2020. One species of sea pen was recorded as present at the stations surveyed: Virgularia mirabilis. Trawl marks were observed at 24% of the stations surveyed.
    • 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 (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.