• Blue Whiting Acoustic Survey Cruise Report Spring 2008

      O'Donnell, C; Mullins, E; Johnston, G; Lyons, K; Bethke, E; Holst, G; Wall, D (Marine Institute, 2008)
      Acoustic surveys on the blue whiting (Micromesistius poutassou) stock in the north east Atlantic have been carried out by the Institute of Marine Research (IMR), Norway since the early 1970s. In the early 1980s a coordinated acoustic survey approach was adopted, with both Russia and Norway participating to estimate the size of this migratory stock within its key spawning grounds. Since 2004, the coordinated survey program has expanded and to include vessels from the EU (Ireland and the Netherlands) and the Faroes. Due to the highly migratory nature of the stock a large geographical area has to be surveyed. Spawning takes place from January through to April, with a peak time between mid-March and mid-April. Consequently acoustic surveys are routinely carried out during the peak spawning period within known geographic confines. To facilitate a more coordinated spatiotemporal approach to the survey participating countries meet annually to discuss survey methods and define target areas at the ICES led Planning Group of Northern Pelagic Ecosystem Surveys (PGNAPES). Data from the annual spawning stock abundance survey (March/April, western waters), juvenile surveys (May, Norwegian Sea and January-March, Barents Sea trawl survey) and commercial landings data are presented annually at the ICES Working Group of Widely Distributed Stocks (WGWDS). Ultimately, combined data inputs into the management and catch advice for this international cross boundary stock. The 2008 survey was part of an International collaborative survey using the vessels RV Celtic Explorer (Ireland), RV Fridtjof Nansen (Russia), RV Tridens (Netherlands) and the RV Magnus Heinason (Faroes) and the FV Gardar (Norwegian commercial charter). The total combined area coverage in 2008 extended from the Faroe Islands in the north (62°N) to south of Ireland (51.30°N), with east - west extension from 5°-19° W. Combined area coverage included shelf break areas (>250m) and large bathymetric features including the slope areas of the Porcupine, Rockall and Hatton Banks. The Irish component of the survey was made up of transects covering 2,480nmi (nautical miles) covering the slope areas (>250m) of the north Porcupine area, the eastern fringes of the Rockall Bank, the Rockall Trough and the eastern slopes of the Hebrides shelf. This survey represents the 5th survey in the Irish time series.
    • Celtic Sea Herring Acoustic Survey Cruise Report 2008

      O'Donnell, C; Saunders, R; Lynch, D; Lyons, K; Wall, D (Marine Institute, 2008)
      In the southwest of Ireland and the Celtic Sea (ICES Divisions VIIaS, g & j), herring are an important commercial species to the pelagic and polyvalent fleet. The local fleet is composed of dry hold polyvalent vessels and a small number of purpose built RSW (Refrigerated seawater) vessels. The stock is composed of both autumn and winter spawning components and the fishery targets pre-spawning and spawning aggregations. The Irish commercial fishery has historically taken place within 1-20nmi (nautical miles) of the coast and focused on aggregated schools within the spawning cycle. In recent years the larger RSW vessels have actively targeted offshore summer feeding aggregations in the south Celtic Sea. In VIIj, the fishery traditionally begins in mid September and is concentrated within several miles of the shore including many bays and inlets. The VIIaS fishery peaks towards the year end in December, but may be active from mid October depending on location. In VIIg, along the south coast herring are targeted from October to January at a number of known spawning sites and surrounding areas. Overall, the protracted spawning period of the two components extends from October through to January, with annual variation of up to 3 weeks. Spawning occurs in successive waves in a number of well known locations including large scale grounds and small discreet spawning beds. The geographical confines of the annual 21 day survey have been modified in recent years to include areas to the south of the main winter spawning grounds in an effort to identify the whereabouts of winter spawning fish before the annual inshore spawning migration. Spatial resolution of acoustic transects has been increased over the entire south coast survey area. The acoustic component of the survey has been further complimented by detailed hydrographic and marine mammal and seabird work programs first initiated during this survey in 2004.
    • Celtic Sea Herring Acoustic Survey Cruise Report 2010

      Saunders, R; O'Donnell, C; Campbell, A; Lynch, D; Egan, A; Lyons, K; Wall, D (Marine Institute, 2010)
      In the southwest of Ireland and the Celtic Sea (ICES Divisions VIIaS, g & j), herring are an important commercial species to the pelagic and polyvalent fleet. The local fleet is composed of dry hold polyvalent vessels and a small number of purpose built Refrigerated seawater vessels (RSW). The stock is composed of both autumn and winter spawning components and the fishery targets pre-spawning and spawning aggregations. The Irish commercial fishery has historically taken place within 1-20 nmi (nautical miles) of the coast and focused on aggregated schools within the spawning cycle. In recent years the larger RSW vessels have actively targeted offshore summer feeding aggregations in the south Celtic Sea. In VIIj, the fishery traditionally begins in mid September and is concentrated within several miles of the shore including many bays and inlets. The VIIaS fishery peaks towards the year end in December, but may be active from mid October depending on location. In VIIg, along the south coast herring are targeted from October to January at a number of known spawning sites and surrounding areas. Overall, the protracted spawning period of the two components extends from October through to January, with annual variation of up to 3 weeks. Spawning occurs in successive waves in a number of well known locations including large-scale grounds and small discreet spawning beds. The stock structure and discrimination of herring in this area has been investigated recently. Hatfield et al. (2007) has shown the Celtic Sea stock to be fairly discrete. However, it is known that fish in the eastern Celtic Sea recruit from nursery areas in the Irish Sea, returning to the Celtic Sea as young adults (Brophy et al. 2002; Molloy et al., 1993). The stock identity of VIIj herring is less clear, though there is evidence that they have linkages with VIIb and VIaS (ICES, 1994; Grainger, 1978). Molloy (1968) identified possible linkages between young fish in VIIj and those of the Celtic Sea herring. For the purpose of stock assessment and management divisions VIIaS, VIIg and VII j have been combined since 1982. For a period in the 1970s and 1980s, larval surveys were conducted for herring in this area. However, since 1989, acoustic surveys have been carried out, and currently are the only tuning indices available for this stock. In the Celtic Sea and VIIj, herring acoustic surveys have been carried out since 1989, and this survey is the 19th in the overall acoustic series or the sixth in the modified time series (i.e. conducted in October). The geographical confines of the annual 21 day survey have been modified in recent years to include areas to the south of the main winter spawning grounds in an effort to identify the whereabouts of winter spawning fish before the annual inshore spawning migration. Spatial resolution of acoustic transects has been increased over the entire south coast survey area. The acoustic component of the survey has been further complimented by detailed hydrographic and marine mammal and seabird work programs first initiated during this survey in 2004.
    • Celtic Sea Herring Acoustic Survey Cruise Report and Biomass Estimate, 2007

      O'Donnell, C; Egan, A; Lynch, D; Dransfeld, L; Boyd, J; Lyons, K; Wall, D (Marine Institute, 2007)
      In the southwest of Ireland and the Celtic Sea (ICES Divisions VIIaS, g & j), herring are an important commercial species to the pelagic and polyvalent fleet. The local fleet is composed of dry hold polyvalent vessels and a small number of purpose built RSW (Refrigerated seawater) vessels. The stock is composed of both autumn and winter spawning components and the fishery targets pre-spawning and spawning aggregations. The Irish commercial fishery has historically taken place within 1-20nmi (nautical miles) of the coast and focused on aggregated schools within the spawning cycle. In recent years the larger RSW vessels have actively targeted offshore summer feeding aggregations in the south Celtic Sea. In VIIj, the fishery traditionally begins in early October and is concentrated within several miles of the shore including many bays and inlets. The VIIaS fishery peaks towards the year end in December, but may be active from mid October depending on location. In VIIg, along the south coast herring are targeted from October to January at a number of known spawning sites and surrounding areas. Overall, the protracted spawning period of the two components extends from October through to January, with annual variation of up to 3 weeks. Spawning occurs in successive waves in a number of well known locations including large scale grounds and small discreet spawning beds. The geographical confines of the annual 21 day survey have been modified in recent years to include areas to the south of the main winter spawning grounds in an effort to identify the whereabouts of winter spawning fish before the annual inshore spawning migration. Spatial resolution of acoustic transects has been increased over the entire south coast survey area. The acoustic component of the survey has been further complimented by detailed hydrographic and marine mammal and seabird work programs first initiated during this survey in 2004.
    • Celtic Sea Herring Acoustic Survey RV Celtic Explorer 1st – 21st October 2006

      O'Donnell, C; Doonan, I; Lynch, D; Egan, A; Boyd, J; Wall, D; Ullgren, J (Marine Institute, 2006)
      In the Celtic Sea and ICES Division VIIj the herring fishery is divided into 3 main catching seasons. In quarters four and one, the fishery is focused on autumn and winter pre-spawning and spawning aggregations. In the 2004/05 season 34 vessels participated in the fishery, ranging from small dry hold polyvalent vessels (<20m) to purpose built RSW (Refrigerated seawater) vessels of 23-40m. Single and pair midwater trawling are common, with the latter representing the preferred catching method. In recent years a quarter-3 summer fishery has developed targeting offshore feeding aggregations, 78nmi (nautical miles) offshore on the Labadie Bank. This offshore fishery is restricted to the RSW fleet on the grounds of product quality delivered to processors. The 2006 autumn survey is the most comprehensive survey carried out in the current time series. The geographical extent of the annual 21 day survey was extended further offshore to include areas to the south of the main coastal spawning grounds to target winter spawning fish on an inward spawning migration. Spatial resolution of acoustic transects were increased over the entire south coast survey areas, with a special focus on spawning grounds throughout the survey confines. The acoustic component of the survey was complimented by a continuation of the detailed hydrographic work first established in the Celtic Sea in 2004.
    • Celtic Sea Herring Acoustic Survey, Cruise Report 2009

      Saunders, R; O'Donnell, C; Campbell, A; Lynch, D; Lyons, K; Wall, D (Marine Institute, 2009)
      In the southwest of Ireland and the Celtic Sea (ICES Divisions VIIaS, g & j), herring are an important commercial species to the pelagic and polyvalent fleet. The local fleet is composed of dry hold polyvalent vessels and a small number of purpose built Refrigerated seawater vessels (RSW). The stock is composed of both autumn and winter spawning components and the fishery targets pre-spawning and spawning aggregations. The Irish commercial fishery has historically taken place within 1-20 nmi (nautical miles) of the coast and focused on aggregated schools within the spawning cycle. In recent years the larger RSW vessels have actively targeted offshore summer feeding aggregations in the south Celtic Sea. In VIIj, the fishery traditionally begins in mid September and is concentrated within several miles of the shore including many bays and inlets. The VIIaS fishery peaks towards the year end in December, but may be active from mid October depending on location. In VIIg, along the south coast herring are targeted from October to January at a number of known spawning sites and surrounding areas. Overall, the protracted spawning period of the two components extends from October through to January, with annual variation of up to 3 weeks. Spawning occurs in successive waves in a number of well known locations including large scale grounds and small discreet spawning beds. The stock structure and discrimination of herring in this area has been investigated recently. Hatfield et al. (2007) has shown the Celtic Sea stock to be fairly discrete. However, it is known that fish in the eastern Celtic Sea recruit from nursery areas in the Irish Sea, returning to the Celtic Sea as young adults (Brophy et al. 2002; Molloy et al., 1993). The stock identity of VIIj herring is less clear, though there is evidence that they have linkages with VIIb and VIaS (ICES, 1994; Grainger, 1978). Molloy (1968) identified possible linkages between young fish in VIIj and those of the Celtic Sea herring. For the purpose of stock assessment and management divisions VIIaS, VIIg and VII j have been combined since 1982. For a period in the 1970s and1980s, larval surveys were conducted for herring in this area. However, since 1989, acoustic surveys have been carried out, and currently are the only tuning indices available for this stock. In the Celtic Sea and VIIj, herring acoustic surveys have been carried out since 1989, and this survey represents the 18th in the overall acoustic series or the fourth in the modified time series. The geographical confines of the annual 21 day survey have been modified in recent years to include areas to the south of the main winter spawning grounds in an effort to identify the whereabouts of winter spawning fish before the annual inshore spawning migration. Spatial resolution of acoustic transects has been increased over the entire south coast survey area. The acoustic component of the survey has been further complimented by detailed hydrographic and marine mammal and seabird work programs first initiated during this survey in 2004.
    • Deep Water Survey, 2008 Celtic Explorer 9th – 22nd September 2008

      O'Hea, B; Johnston, G; Leahy, Y; Mohn, C; Wall, D; Gerritsen, H.D. (Marine Institute, 2009)
      The Marine Institute and the National University of Ireland, Galway conducted a deepwater survey in September 2008. This survey was the third in a series, carried out on the RV Celtic Explorer, gathering fishery and hydrographic data on the continental slope to the north and west of Ireland, and on the Porcupine Bank. The survey objectives were to collect biological data on the main deepwater fish species and invertebrates. Fishing hauls were carried out at four depths, 500m, 1000m, 1500m, and 1800m, in each of three distinct Areas. Six comparative tows were carried out with Scottish Fisheries Science Service scientists aboard the RV Scotia. CTD data was collected along transects in each area. Cetacean observations were carried out by an observer from the Irish Whale and Dolphin Group. The fisheries data collected will provide information for assessment of deepwater stocks, and will provide a time series for CPUE. 122 species of fish were identified, with a further 8 taken ashore for further work.
    • Deepwater Survey Report 2006

      Hareide, N; O'Hea, B; Johnston, G; Leahy, Y; McCormick, E; Trueman, C; Wall, D; Gerritsen, H.D. (Marine Institute, 2006)
      The Marine Institute fisheries science services carried out a deepwater survey in 2006, to revisit earlier survey areas from the nineties and investigate the impact of the high levels of exploitation on the abundance and biological parameters of the deepwater species. The survey was carried out in three areas, two of which were located on the western continental slope and the third on the northern slope of the Porcupine Bank. Hauls were made at four depths, 500m, 750m, 1000m and 1500 meters. Eight comparative tows were made with the Scottish research vessel, RV Scotia. The object of the survey was to collect biological information on the main deepwater fish species, and also to collect benthic invertebrates and bottom sediment samples. CTD transects, grab sampling, and cetacean studies were also carried out. 126 species of fish were identified along with 131 species of invertebrates. The survey will be the basis for further collaborative work with FRS in future years, and provide a timeseries for CPUE for the main deepwater species.
    • Irish Multidisciplinary Deepwater Survey 2007 SSTI Project Report

      Dransfeld, L; Davie, S; Johnston, G; Leahy, Y; O'Beirn, F.X.; O'Hea, B; O'Shea, C; Wall, D; White, M; Gerritsen, H.D. (Marine Institute, 2007)
      The Marine Institute with the collaboration of the National University of Galway conducted a multidisciplinary deepwater survey along the continental slope of the Northeast Atlantic. At three selected sites northwest of Ireland and on the northern slopes of the Porcupine Bank, fishing transects were carried out at four depth strata (500m, 1000m 1500m and 1800m) during the day, while oceanographic measurements and plankton and benthic invertebrate sampling was carried out during the night. Data from CTD and ADCP measurements showed following distribution of water masses: The top 700 m was occupied by that of Eastern North Atlantic Water (ENAW) origin which is a basic feature of the upper layer hydrography in the Rockall Trough; small salinity maxima indicated the region associated with the core of the shelf edge current (SEC). At Area 6, immediately north of Porcupine Bank, a salinity maximum at a depth of 900-1000 m indicated the presence of Mediterranean Outflow Water (MOW) with the presence Labrador Sea Water (LSW) at 1800-2000 m. The SEC was identified in both CTD and ADCP transects and was characterised by a number of relatively narrow filaments evident in the salinity data. In terms of benthic invertebrate data, a total of 104 taxa were identified with a maximum number of 33 invertebrate taxa identified per haul (these values were recorded at two 1500m hauls in 2006 and 2007, in Areas 5 and 2, respectively). Overall, no clear relationship between the number of invertebrate species and depth was apparent, however there was some indication that the number of species appears to be more variable in deeper waters. Several species occurred in very large numbers; these were the echinoderms, Cidaris cidaris, Benthegone rosea and Stichopus tremulus and the bivalve, Pseudammusium septemradii. Fisheries data revealed distinct deepwater fish communities that changed with depth and to a lesser extent with area. The number of species increased with depth at all sites to reach a maximum at 1500m before decreasing again at 1800m. At 500m depth the fish community was mainly composed of rabbit fish and rattails with some shelf species present such as hake, ling and silver pout. The 1000m depth strata presented a transition of species composition. The most abundant species overall was Roundnose grenadier which had is highest abundance at 1500m in all three areas but could also be found in the 1000 and 18000m depth strata. Other species of high abundance which also had their highest number of individuals at 1500m were Baird’s smoothhead and other species of grenadiers. Cluster analysis revealed that Roundnose grenadier was a distinct species grouping as was that of Baird’s smoothhead. Species occurrences were similar in all three areas with some regional differences; in area 2, Phycis blennoides, greater forkbeard,occurred among the ten most abundant species while in area 5, species, such as Black Scabbard, Aphanopus carbo, and cut throat eel, Synaphobranchus kaupi, were being caught here in larger numbers while present in the other areas in low numbers. Seven comparative tows were carried out with the Scottish research vessels RV Scotia and indicated that overall similar numbers of species and total number of fish were caught. Size distribution also compared well between the two different vessels, however for some species the numbers or size ranges of fish caught differed.
    • Northwest Herring Acoustic Survey Cruise Report and Abundance Estimate, 2007

      O'Donnell, C; Egan, A; Lynch, D; Boyd, J; Wall, D; Goddjin, L (Marine Institute, 2007)
      The northwest and west coast herring acoustic survey programme was first implemented in 1994, with the current winter spawning survey representing the 9th in the time series. The stock in this area is composed of 2 spawning components (autumn and winter), covering a large geographical area. Spawning occurs over a protracted period of over 4-months from late September through to late March. The age profile of the survey stock as generated from trawl samples indicated ages ranging from 1-7 years. Maturity samples indicate the largest proportion of the stock to be in a pre-spawning, spawning or spent state, with small amounts of immature fish, as would be expected at this time. The 2007 survey estimate generated a TSB (total stock biomass) of 14,200 t relating to a SSB (spawning stock biomass) of 13,974 t. Poor weather dominated the survey with almost 25% lost in downtime. As a result the survey area and track lines had to be reduced to compensate and hydrographic stations had to be sacrificed. The poor weather experienced no doubt had an impact on herring schooling behaviour and our detection ability.