• Blue Whiting Acoustic Survey Cruise Report March-April 2004

      O’Donnell, Ciaran; Mullins, Eugene; Monstad, Terje; Macualay, Gavin; Power, Gavin; Ullgren, Jenny (Marine Institute, 2004)
      Acoustic surveys on northern blue whiting (Micromesistius poutassou) stocks have been carried out since the early 1970s by the Institute of Marine Research (IMR), Bergen. In the early 1980s a coordinated acoustic survey approach was adopted, with both Russia and Norway participating to estimate the size of the stock. The acoustic survey programme is carried out for fishery management purposes, results are presented annually at the ICES led Northern Pelagic and Blue Whiting Fisheries Working Group and from this catch advice is determined for the following year. The highly migratory nature of this stock and its components require a large geographical area to be surveyed during a relatively short spawning window. Acoustic surveys are routinely carried out on specific spawning and pre-spawning aggregations of blue whiting. This can allow for high concentrations of fish to be surveyed in a relatively small geographical and often well defined area, if the timing is synchronised. This survey was conducted as part of a collaborative survey coordinated by the Institute of Marine Research, Bergen, Norway, using the vessel the MRV “Johan Hjort”. Also participating were the MRV “Fridtjof Nansen” (PINRO, Russia) and the MRV “Tridens” (RIVO, Netherlands). The total combined area surveyed in 2004 covered from the Faroe Islands in the north (62º of longitude) to the southern coast of Ireland (50.5º N), area coverage to the west extended from 2º -18º of latitude. The Irish component of the survey was made up of transects covering some 2,080 nautical miles. In addition to the collection of acoustic data fishing hauls were carried out to determine the make up of fish marks recorded by the equipment and to assess the length, weight, age, sex and maturity of the stock. Oceanographic data was collected using a number of spaced hydrograhic stations where salinity and temperature of the water column was recorded at depths of up to 1200 m.
    • Celtic Sea Herring Acoustic Survey Cruise Report 2004

      O'Donnell, Ciaran; Griffin, Karen; Clarke, Maurice; Lynch, Deirdre; Ulgren, Jenny; Goddijn, Lonneke; Wall, David; Mackey, Mick (Marine Institute, 2004)
      In the Celtic Sea and ICES Division VIIj, to the south and southwest of Ireland, herring is an important commercial species and currently Ireland is the only country targeting this species in this area. Herring in this region comprise both autumn and winter spawning components. Commercial fishing has targeted the fish during spawning times, though in most recent years fish have been targeted during the summer feeding phase too. In VIIj, fishing has traditionally taken place in October, and concentrated in the bays and inlets. In contrast, fishing in VIIaS has mainly been in December to January, though in VIIg the fishery traditionally takes place from November to January. The protracted spawning period of herring and the overlap between the two spawning socks in this area (October to February) means that it is difficult to design a survey that covers all spawning fish in one specific survey. The stock structure and discrimination of herring in this area is not fully understood. It is known that fish in the eastern Celtic Sea recruit from nursery areas in the Irish Sea and tagging studies have shown linkages between these areas also. For the purpose of stock assessment and management these areas have been combined since 1982. A project is currently underway to describe stock structure and discrimination of herring around Ireland. The results of this project may have implications for the design of this survey and for the stock assessment. For a period in the 1980’s, egg and 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. In the Celtic Sea and VIIj, herring acoustic surveys have been carried out since 1989, and the current survey is the 15th in the series. In addition to the survey track a small component (Baginbun) was intensively surveyed using acoustic and multibeam mapping techniques. The Baginbun area is located east of Waterford Harbour in ICES division VIIaS. Baginbun has supported a large winter fishery for many years and is one of the most important and well known winter spawning areas on the south coast. This year for the first time the RV Celtic Explorer was to survey the area. This allowed a more extensive degree of coverage in the time allocated, the survey was further complemented with a number of hydrographic transects concentrating along the bays in the west and southwest and also along the southern coastline.
    • Northwest Herring Acoustic Survey Report 2004

      O'Donnell, Ciaran; Mullins, Eugene; Egan, Afra; Smith, Turloch; Bunn, Robert; Griffin, Karen; O’Driscol, Patrick; Bicknell, Simon; O’Driscol, Deirdre; Cross, Marcus; et al. (Marine Institute, 2004)
      The objectives of this survey were to: 1). To assess the size of the herring stock in VIaS and VIIb using an EK60 scientific sounder and a 38 kHz mounted within the vessels drop keel. Observe fish marks along the survey track using 18, 120 and 200 kHz; 2). Collect biological data from herring samples within this area and determine composition of marks using a single pelagic mid-water trawl.
    • Biological Sampling Survey: Celtic Voyager March 2004

      Marine Institute (Marine Institute, 2005)
      The survey is intended to address the requirements of the Data Collection Regulation 1639/2001. Information on growth, maturity and sex ratio (biological data) were collected for a range of commercially important species. Ovary samples were collected to validate visual maturity staging. Additionally, ovary samples were taken for CEFAS in Lowestoft, tissue samples were taken for genetics projects within the Marine Institute as well as other labs. Samples of whole flatfish were taken for meristics analysis in GMIT.
    • Celtic Sea Herring Acoustic Survey Cruise Report 2005

      O'Donnell, Ciaran; Doonan, Ian; Johnston, Graham; Lynch, Deirdre; Dransfeld, Leonie; Wall, David (Marine Institute, 2005)
      In the Celtic Sea and ICES Division VIIj, to the south and southwest of Ireland, herring are an important commercial species to the pelagic fleet. The local fleet is composed of dry hold polyvalent vessels and a number of purpose built RSW (Refrigerated seawater) vessels. This stock is composed of both autumn and winter spawning components. The commercial fishery has historically taken place within 6nmi (nautical miles) of the coast and focused on aggregated schools within the spawning cycle. In recent years the RSW fleet has actively targeted offshore summer feeding grounds in the south Celtic Sea. In division VIIj, the fishery traditionally begins in early October and is concentrated within several miles of the shore bays and inlets. The division VIIaS fishery peaks towards the year end in December, but may be active from mid October depending on location. In division 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 is not fully understood. It is known that fish in the eastern Celtic Sea recruit from nursery areas in the Irish Sea and tagging studies have shown linkages between these areas also. For the purpose of stock assessment and management these areas have been combined since 1982. For a period in the 1980’s, egg and 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. In the Celtic Sea and VIIj, herring acoustic surveys have been carried out since 1989, and the current survey is the 16th in the series. The autumn 2005 survey is the most comprehensive survey carried out in the current time series. The geographical confines of the annual 21 day survey were expanded 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 were increased over the entire south coast survey areas. The acoustic component of the survey was complimented by a continuation of the detailed hydrographic work carried out in the Celtic Sea in 2004. In addition a second inshore survey was carried out along the southern coast using a chartered commercial fishing vessel (FV Regina Ponti). This second survey focused on area between 0.5nmi and 10nmi offshore and covered the main autumn and winter spawning areas along the south coast.
    • Northwest Herring Acoustic Survey Report 2005

      O'Donnell, Ciaran; Mullins, Eugene; Johnston, Graham; Power, Ayesha; Beatie, Susan (Marine Institute, 2005)
      The northwest and west coast herring acoustic survey programme was first implemented in 1994. Prior to this a larval survey programme was carried out between 1981 and 1986. The ICES herring working group (HAWG) identified the need for a dedicated herring acoustic survey in this area (Anon, 1993). The stock in this area is composed of a number of spawning components and spawning may extend from September through to March (Molloy et al, 2000). Commercial fishing has targeted the fish during spawning times, no summer matje fishery exists in this area. In VIaS, fishing has traditionally taken place in late December and continues until late February (winter spawners). Traditionally in VIIb, fishing is mainly concentrated on the later months of the year and would be concluded by the early part of the new year (Autumn spawners). The protracted spawning period of herring and the overlap between the two spawning socks in this area (October to February) means that it is difficult to design a survey that covers all spawning fish in one specific survey. A project is currently underway to describe stock structure and discrimination of herring around Ireland. The results of this project may have implications for the design of this survey and for the stock assessment. However, since 1994, acoustic surveys have been carried out, and currently are the only tuning indices available. The current survey makes up the 11th in the time series. The design and execution of this survey has evolved from summer feeding phase surveys, in the mid 1990s until its present winter spawning state.
    • Blue Whiting Acoustic Survey Cruise Report March-April 2005

      O’Donnell, Ciaran; Mullins, Eugene; Power, Gavin; Goddijn, Lonneke; Mackey, Mick (Marine Institute, 2005)
      Acoustic surveys on northern blue whiting (Micromesistius poutassou) stocks have been carried out since the early 1970s by the Institute of Marine Research (IMR), Bergen. In the early 1980s a coordinated acoustic survey approach was adopted, with both Russia and Norway participating to estimate the size of the stock. The acoustic survey programme is carried out for fishery management purposes, results are presented annually at the ICES led Northern Pelagic and Blue Whiting Fisheries Working Group and from this catch advice is determined for the following year. The highly migratory nature of this stock and its components require a large geographical area to be surveyed during a relatively short spawning window. Acoustic surveys are routinely carried out on specific spawning and pre-spawning aggregations of blue whiting. This can allow for high concentrations of fish to be surveyed in a relatively small geographical and often well defined area, if the timing is synchronised. This survey was conducted as part of a collaborative survey coordinated by the Institute of Marine Research, Bergen, Norway, using the vessel the RV “G.O. Sars”. Also participating were the RV “Fridtjof Nansen” (PINRO, Russia), RV “Atlantniro” (Russia), RV “Tridens” (RIVO, Netherlands) and the RV “Magnus Heinason” (Faroes). The total combined area surveyed in 2005 covered from the Faroe Islands in the north (62º of longitude) to the southern coast of Ireland (49º N), area coverage to the west extended from 2º -20º of latitude. The Irish component of the survey was made up of transects covering some 2,228 nautical miles. In addition to the collection of acoustic data fishing hauls were carried out to determine the make up of fish marks recorded by the equipment and to assess the length, weight, age, sex and maturity of the stock. Oceanographic data was collected using a number of spaced hydrograhic stations where salinity and temperature of the water column was recorded at depths of up to 1200 m.
    • Cruise Report Biological Sampling Survey 2005

      Marine Institute (Marine Institute, 2006)
      The survey is intended to address the requirements of the Data Collection Regulation 1639/2001. Information on growth, maturity and sex ratio (biological data) were collected for a range of commercially important species. Ovary samples were collected to validate visual maturity taging.
    • 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.
    • 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.
    • International Blue Whiting Spawning Stock Survey Spring 2006

      Marine Institute; Institute of Marine Research; AtlantNIRO; PINRO; National University of Ireland, Galway; Faroese Fisheries Laboratory; Institute for Marine Resources & Ecosystem Studies; Danish Institute for Fisheries Research (Marine Institute, 2006)
      In spring 2006, five research vessels representing the Faroe Islands, Ireland, the Netherlands, Norway and Russia surveyed the spawning grounds of blue whiting west of the British Isles. International co-operation allows for wider and more synoptic coverage of the stock and more rational utilisation of resources than uncoordinated national surveys. The survey was the second coordinated international blue whiting spawning stock survey since mid-1990s. The primary purpose of the survey was to obtain estimates of blue whiting stock abundance in the main spawning grounds using acoustic methods as well as to collect hydrographic information. Results of all the surveys are also presented in national reports (Atlantniro: Shnar et al. 2006; Celtic Explorer: Mullins et al. 2006; G. O. Sars: Heino et al. 2006; M. Heinason: Jacobsen et al. 2006; Tridens: Ybema et al. 2006). This report is based on a workshop held after the international survey in Tórshavn, 20–21/4/2006, where the data were analysed and the report written. Parts of the document were worked out through correspondence during and after the workshop.
    • Blue Whiting Acoustic Survey Cruise Report March-April 2006

      Mullins, Eugene; Johnston, Graham; Power, Gavin; Goddijn, Lonneke; Mackey, Mick (Marine Institute, 2006)
      Acoustic surveys on the blue whiting (Micromesistius poutassou) stock in the north east atlantic have been carried out since the early 1970s by the Institute of Marine Research (IMR), Norway. In the early 1980s a coordinated acoustic survey approach was adopted, with both Russia and Norway participating to estimate the size of the combined stock. The acoustic survey programme is carried out for fishery management purposes and is continued to date. Results of this annual spawning stock assessment combined with juvenile surveys and commercial catch at age data are presented annually at the ICES led Northern Pelagic and Blue Whiting Fisheries Working Group. Ultimately, from this combined scientific data, management and catch advice is determined for the following year. The highly migratory nature of the combined stock requires a large geographical area to be surveyed during a protracted spawning period. Consequently Acoustic surveys are routinely carried out on specific spawning and post-spawning aggregations of blue whiting. To facilitate a more coordinated spatio-temporal approach to spawning stock assessment, several nations became involved in the PGNAPES coordinated survey programme in 2004. Ireland is one of these nations involved in this annual survey. The 2006 survey was part of an International collaborative survey coordinated by the Institute of Marine Research, Bergen, Norway, using the vessel the RV “G.O. Sars”. Also participating were the RV “Atlantniro” (Russia), RV “Tridens” (RIVO, Netherlands) the RV “Magnus Heinason” (Faroes) and RV “Celtic Explorer” (Ireland). The total combined area surveyed in 2006 covered from the Faroe Islands in the north (62°of longitude) to the southern coast of Ireland (51° N), area coverage to the west extended from 4°-18° of latitude. The Irish component of the survey was made up of transects covering some 2,632 nautical miles (Figure 1). In addition to the collection of acoustic data, fishing hauls were carried out to determine the make up of fish marks recorded by the equipment and to assess the length, weight, age, sex and maturity of the stock. Oceanographic data was collected using a number of spaced hydrograhic stations where salinity and temperature of the water column was recorded at depths down to 800m.
    • Northwest Herring Acoustic Survey Report 2006

      O'Donnell, Ciaran; Doonan, Ian; Lynch, Deirdre; O’Hea, Brendan; Egan, Afra (Marine Institute, 2006)
      The northwest and west coast herring acoustic survey programme was first implemented in 1994. Prior to this a larval survey programme was carried out between 1981 and 1986. In the early 1990s, the ICES herring working group (HAWG) identified the need for a dedicated herring acoustic survey in this area (Anon, 1994). The stock in this area is composed of 2 spawning components (autumn and winter), covering a large geographical area. Spawning may extend over a 4 month period from late September through to late March (Molloy et al, 2000). Traditionally fishing activity has targeted spawning and pre-spawning aggregations, no summer matje fishery exists in this area, as is the case in the Celtic Sea. In VIaS, fishing has traditionally taken place in late October and continues until late February (winter spawners). Traditionally in VIIb, fishing is mainly concentrated on the later months of the year and would be concluded by the early part of the new year (Autumn spawners). The protracted spawning period of herring and the overlap between the two spawning stocks in this area (October to February) is highly dynamic with variations between annual spawning events of up to 3 weeks. Accurate survey timing is a key component of the design to cover the overlap of peak spawning events. A project is currently underway to describe stock structure and discrimination of herring around Ireland. The results of this project may have implications for the design of this survey and for the stock assessment. However, since 1994, acoustic surveys have been carried out, and currently are the only tuning indices available. The current survey makes up the 13th in the time series. The design and execution of this survey has evolved from summer feeding phase surveys, in the mid 1990s until its present winter spawning state. This is the third survey of this stock carried out by the Celtic Explorer.
    • Mackerel Egg survey, March 6th – 26th, 2007

      O'Hea, B (Marine Institute, 2007)
      Every three years the International Council for the Exploration of the Sea (ICES) coordinates a series of mackerel and horse mackerel egg surveys covering the eastern Atlantic from Gibraltar to the north coast of Scotland between January and July. The aim of this survey programme is to assess the northeastern Atlantic mackerel and horse mackerel stock. The Marine Institute participates in this programme and covers stations in the Celtic Sea. Plankton samples were collected at 112 stations, and the eggs they contained were preserved in 4% buffered formaldehyde. Preliminary analysis shows that egg numbers were concentrated close to the shelf edge, around the 200m contour line. Eleven fishing hauls were made to collect mackerel and horse mackerel samples for fecundity analysis. Samples were collected to ensure maximum temporal and geographical spread. CTD’s were also carried out for the Oceanography section of the Marine Institute.
    • Survey Report: Biological Sampling Survey 16-25 February 2007, Celtic Sea

      Gerritsen, H.D. (Marine Institute, 2007)
      The Biological Sampling Survey took place on 16-25 February in Celtic Sea on the Celtic Voyager. The survey is intended to address the requirements of the Data Collection Regulation 1639/2001. Information on growth, maturity and sex ratio (biological data) were collected for a range of commercially important species.
    • 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.
    • Blue Whiting Acoustic Survey Cruise Report Spring 2007

      O'Donnell, C; Mullins, E; Johnston, G; Beattie, S; Ullgren, J; Heino, M; Anthonypillai, V (Marine Institute, 2007)
      Acoustic surveys on the blue whiting (Micromesistius poutassou) stock in the north east Atlantic have been carried out since the early 1970s by the Institute of Marine Research (IMR), Norway. 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 now includes vessels from the Netherlands, Faroes and Ireland in addition to those from the Russian Federation and Norway. 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 early 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 this spawning stock 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), juvenile surveys (May) and commercial landings data are presented annually at the ICES led Northern Pelagic and Blue Whiting Fisheries Working Group (WGNPBW). Ultimately, combined data inputs into the management and catch advice for this cross boundary stock. The 2007 survey was part of an International collaborative survey using the vessels RV “Celtic Explorer” (Marine Institute, Ireland), RV “Atlantida” (AtlantNIRO, Russian Federation), RV “Tridens” (IMARES, Netherlands) and the RV “Magnus Heinason” (FRS, Faroes) and the FV “Eros” (IMR commercial charter). The total combined area coverage in 2007 extended from the Faroe Islands in the north (61.30°N) to south of Ireland (50.30°N), with east –west extension from 5°-19° W. Combined area coverage included shelf break areas (>200m) and large bathymetric features including the Porcupine, Rockall and Hatton Banks. The Irish component of the survey was made up of transects covering 2,624 nmi (nautical miles) covering the north Porcupine area, the eastern and western fringes of the Rockall Bank and the western slopes of the Hatton Bank. This survey represents the 4th survey in the Irish time series.
    • Cruise Report Biological Sampling Survey 2006: Irish Sea 24 February to 5 March

      Marine Institute (Marine Institute, 2007)
      The survey is intended to address the requirements of the Data Collection Regulation 1639/2001. Information on growth, maturity and sex ratio (biological data) were collected for a range of commercially important species. Ovary samples were collected to validate visual maturity staging and to provide fecundity samples for the Irish Sea Egg Production Project in collaboration with CEFAS (Lowesoft) and DARDNI (Belfast). Samples of various squid species were collected for genetic analysis by ANFACO-CECOPESCA (Vigo, Spain).
    • 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.
    • 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.