• 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.
    • Western Irish Sea Nephrops Grounds (FU15) 2015 UWTV Survey Report and catch options for 2016

      Clements, 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, 2015)
      This report provides the main results and findings of the 13th annual underwater television survey on the ‘Irish sea west Nephrops grounds’ ICES assessment area, Functional Unit 15.
    • Western Irish Sea Nephrops Grounds (FU15) 2017 UWTV Survey Report and catch options for 2018

      Clements, A.; Doyle, J.; Lordan, C.; Lundy, M.; McCorriston, P.; McArdle, J.; McCausland, I.; Burns, G.; Schön, P.J. (Marine Institute, 2017)
      This report provides the main results and findings of the 15th 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 2017 design consisted of a randomised isometric grid of 100 stations at 4.5 nautical mile intervals out over the full known extent the stock. The resulting krigged burrow abundance estimate was 5.3 billion burrows. This was a similar result of that obtained in 2006, and 4% higher than the abundance in 2016. In contrast to 2016 the spatial distribution of burrows appears more homogenous across the survey area. Overall densities are high and abundance remains stable, well above MSY Btrigger. Reducing the number of stations compared to 2011 has not affected the accuracy of the survey estimate to date. 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 2017 implies a total catch option at Fmsy (=Fmax) of 11,807 tonnes which results in landings of no more than 9,630 tonnes. The only sea-pen species observed in 2017 was Virgularia mirabilis and this was found at 16% of stations ranging from occasional to common, with high densities observed in the south-west of the ground. Trawl marks were noted at 36% of the UWTV stations.
    • Western Irish Sea Nephrops Grounds (FU15) 2018 UWTV Survey Report and catch options for 2019

      Clements, A.; Butler, R.; Doyle, J.; Ourens, R.; Lordan, C.; McCorriston, P.; Burns, G.; McCausland, I.; Erskine, K.; Lilley, K.; Heaney, G.; Lundy, M.; Schön, P.J. (Marine Institute, 2018)
      This report provides the main results and findings of the 16th 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 2018 design consisted of a randomised isometric grid of 100 stations at 4.5 nautical mile intervals out over the full known extent the stock. The resulting krigged burrow abundance estimate was 4.9 billion burrows. This was a similar result of that obtained in 2011, and 9% lower than the abundance in 2017. In contrast to 2017 the spatial distribution of burrows appears more homogenous across the survey area, with high densities in the SW of the ground in shallower water, and higher densities in the NW of the ground in deep water. Overall densities are high and abundance remains stable, well above MSY Btrigger. Reducing the number of stations compared to 2011 has not affected the accuracy of the survey estimate to date. 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 2018 implies a total catch option at Fmsy (=Fmax) of 11,107 tonnes which results in landings of no more than 8,959 tonnes. The sea-pen species observed in 2018 was predominantly Virgularia mirabilis, with one potential observation of Pennatula phosphorea (which requires verification). Sea-pens were observed at 20% of stations with high densities observed in the south-west of the ground. Trawl marks were noted at 26% of the UWTV stations.