• Aran, Galway Bay and Slyne Head Nephrops Grounds 2006 UWTV Survey Report

      Lordan, C; Doyle, J; Sacchetti, F; O'Driscoll, D; Heir, I; Smith, T; Allsop, C (Marine Institute, 2007)
      The Nephrops fishery “at the back of the Aran Islands” is the mainstay of the Ros a Mhíl fleet and sustaining this valuable fishery would be at the heart of any management plan for fisheries in the area. In 2006 the fifth in a series of annual UWTV survey was completed, and the results of that survey together with a synthesis and analysis of the results were published. The survey is multidisciplinary in nature collecting data on burrow abundances from UWTV, Nephrops biological data from beam trawls, oceanographic data from CTD, sediment data, multi-beam and other habitat data. A geostatistical analysis indicates that burrow densities and abundances have fluctuated considerably in space and time. Highest densities occurred in 2004 with the lowest densities in the 2006 survey. There may be a negative relationship between abundance in landings in the autumn and a positive relationship between observed densities and landings the following spring.
    • 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.
    • 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.
    • 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.
    • 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.
    • 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.
    • 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.
    • Aran, Galway Bay and Slyne Head Nephrops Grounds 2009 UWTV Survey Report

      Lordan, C; Doyle, J (Marine Institute, 2009-09)
      The prawn (Nephrops norvegicus) are common around the Irish coast occurring in geographically distinct sandy/muddy areas were the sediment is suitable for them to construct their burrows. The Irish Nephrops fishery is extremely valuable with landings in recent years worth around €30m at first sale supporting an important indigenous processing industry. The Nephrops fishery “at the back of the Aran Islands” can be considered the mainstay of the Ros a Mhíl fleet. Without this Nephrops fishery the majority of vessels in the fleet would cease being economically viable (Meredith, 1999). Given these socio-economic realities, good scientific information on stock status to enable sustainable management of the resources are urgently required. This is the eight 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 26sq.km respectively. 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 and updates 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.
    • 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 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.
    • 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.
    • 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.
    • 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.
    • 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.
    • 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.
    • 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.
    • 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.
    • 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.
    • 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.