• Lobster Trap Census, 1970

      Gibson, F A (Department of Agriculture and Fisheries (Fisheries Division), 1971)
      This leaflet continues the information given in Fishery Leaflets No. 11 and 23 concerning lobster traps in use around the Irish coasts. As in previous years the lobster catch figures supplied to the Fisheries Division by various collectors have been correlated with the fishing gear used by boats fishing off the 12 maritime counties. There was little change in 1970 in the preference of the fishermen for the different designs of fishing traps used.
    • Lobster trap census, 1973

      Bhatnagar, K M (Department of Agriculture and Fisheries (Fisheries Division), 1974)
      This leaflet continues the information provided by Fishery Leaflets numbered, 11, 23, 26, 39, and 57. Although more lobster traps (51.0%) were used in relation to French crawfish, (49.0%) in 1973 (Table 1), the order of preference of lobster fishing (all types) remained the same as in previous years as follows: (a) French crawfish traps (b) Scottish creels (or variation thereof) (c) Other types of traps.
    • Making more money from Periwinkles

      Crowley, M (Department of Agriculture and Fisheries (Fisheries Division), 1975)
      Each year about £250,000 worth of periwinkles are picked on our shores. This makes them far and away the most valuable molluscs in our fishing industry. What is more, the value might be doubled if the catch were to be handled carefully. The fact is that, although they appear very tough, the periwinkle are in some ways delicate animals and rough treatment kills many of them. An important fact in the periwinkle industry is that the resource is a natural one which costs little to exploit. No equipment is required to harvest them because they are simply picked by hand when the tide is out.
    • Mariculture in Ireland. Policies and Problems.

      Went, A E J (Department of Agriculture and Fisheries (Fisheries Division), 1975)
      Mariculture in Ireland up to 1974 was restricted to the flat oyster (Ostrea edulis) and mussel (Mytilus edulis) but since that year rearing of the Atlantic salmon (Salmo salar) in the sea and of some other species has been undertaken on an experimental basis. Because the fisheries in tidal waters and in the sea are, with some exceptions, vested in the public, legal difficulties can arise in many areas. Some of these legal difficulties in the case of the flat oyster, mussel, cockle (Cardium edule) and periwinkle (Littorina littorea) can be resolved by actions under the Irish Fisheries Acts but with other species new legislation is required for certain forms of activity. Problems can also arise in connection with the supply of stock for rearing purposes. Stringent regulations are in force regarding the importation of aquatic animals generally with a view to barring those animals which may have an adverse effect on existing stocks of fish or may lead to the introduction of diseases and parasites not already in the country.
    • Mercury concentration in fish from Irish waters in 1992

      Nixon, E; Rowe, A; McLaughlin, D (Department of the Marine, 1993-08)
      Fish landed at the major Irish ports and molluscs from the main growing areas were sampled during 1992 and analysed for total mercury content. Concentrations in fish species ranged from 0.015 to 1.02 mg/kg wet weight with a mean of 0.1, while in shellfish the concentrations were lower and ranged from 0.005 to 0.049 with a mean of 0.026. The mercury levels recorded in all fish sampled were within the standards for human health applied by the contracting parties to the Oslo and Paris Convention (OSPARCOM). The mean mercury concentrations in only two samples, redfish and crawfish from the west coast, showed levels close to the limit. These species are generally offshore and levels are associated with naturally-occurring mercury rather than with human activity. The survey confirms that Irish seafish of all kinds are effectively free from mercury contamination.
    • Mercury concentration in fish from Irish waters in 1993

      Nixon, E; Rowe, A; McLoughlin, D (Department of the Marine, 1994-11)
      During 1993, a total of 81 samples, covering 18 finfish and 4 shellfish species were collected and the edible portion analysed for total mercury content in accordance with the European Commission's Decision of 19 May 1993. In finfish the concentration of mercury ranged from 0.01 to 0.39 with a mean of 0.10 and in shellfish the concentration also ranged from 0.01 to 0.39 but with a mean of 0.04µg/g wet weight. These levels are low and are well within the maximum limits set by the EC for mercury in fisheries products. The total mercury concentration in Irish shellfish is very low and is generally low in the commercial catch landed at Irish ports. This survey confirms previous studies that show Irish seafoods are effectively free from mercury contamination.
    • Mercury Concentrations in Fish from Irish Waters in 1994

      Nixon, E; Rowe, A; McLaughlin, D (Department of the Marine, 1995-09)
      During 1994, a total of 65 samples, covering the commercially important fish and shellfish species, were collected and the edible portion analysed for total mercury content in accordance with the European Commission's Decision of 19 May 1993. In fish, including prawns, the concentration of mercury ranged from 0.01 to 0.21 with a mean of 0.06 and in shellfish from 0.01 to 0.13 with a mean of 0.04mg/kg wet weight. These levels are low and are well within the maximum limits, 0.05mg/kg wet weight, set by the EC for mercury in fisheries products. This survey confirms previous studies that show Irish seafoods are effectively free from mercury contamination.
    • Metal and Organo-Chlorine Concentrations in Fin-Fish from Irish Waters in 1995

      Rowe, A; Nixon, E; McGovern, E; McManus, M; Smyth, M (Marine Institute, 1998-02)
      During 1995 a total of 44 samples taken from 16 different species of fin-fish were collected from five Irish fishing ports and analysed for total mercury content in the edible tissue, in accordance with the European Commission's Decision of 19 May 1993. The concentration of mercury ranged from 0.03 to 0.28 with a mean of 0.09µg/g wet weight. These levels are low and are well within the maximum limits set by the EC for mercury in fisheries products. This survey confirms previous studies that show Irish seafoods are effectively free from mercury contamination. In addition a number of samples were also analysed for cadmium, copper, lead, zinc, chromium and chlorinated hydrocarbons. Although there are no EU guidelines or standards for these additional contaminants, the levels are well below the strictest standards or guidance values applied by Contracting Parties of the Oslo and Paris Conventions.
    • Monitoring of Shellfish Growing Areas - 1993

      Nixon, E.; Rowe, A.; Smith, M.; McLoughlin, D.; Silke, J. (Department of the Marine, 1994-08)
      During 1993, water and shellfish from 19 major growing areas were monitored for chemical parameters in accordance with the 1979 Council Directive 79/923/EC. At each site temperature, salinity, pH, dissolved oxygen and suspended solids measurements were taken and shellfish samples were returned to the laboratory for metal, chlorinated hydrocarbon and algal biotoxin determinations. Generally, water quality in all areas was good and conformed to the guidelines of the Directive. The highest levels of metals recorded were: cadmium in Tralee Bay (0.4 to 0.7µg/g) and Carlingford Lough (0.3 to 0.7µg/g) and lead in Wexford Harbour (0.5µg/g). Mercury in all cases was low with the exception of Cromane during November when levels of 0.3µg/g were detected. Chlorinated hydrocarbons levels were extremely low and indicate the clean nature of Irish shellfish, unpolluted by these synthetic organic compounds. Algal biotoxins were not detected in any samples.
    • Monitoring of Shellfish Growing Areas - 1994

      Nixon, E; McLaughlin, D; Rowe, A; Smyth, M (Department of the Marine, 1995)
      To fulfil the monitoring requirements of the 1979 Council Directive 79/923/EC on the water quality of shellfish waters, water and shellfish samples were collected from 19 major shellfish-growing areas and analysed for physicochemical parameters and chemical contaminants. At each site temperature, salinity, pH and dissolved oxygen measurements were made and the area was inspected for the presence of petroleum hydrocarbons. Water samples were collected for suspended solids determinations. A representative sample of the shellfish from each area was collected and returned to the laboratory for metal and chlorinated hydrocarbon analyses. As in previous years, the water quality was good and conformed to guidelines and requirements of the Directive. Petroleum hydrocarbons were not observed in any of the shellfish waters or as deposits on the shellfish. Chlorinated hydrocarbon levels were very low, evidence of the clean, unpolluted nature of Irish shellfish and shellfish producing waters. Mercury and lead levels were consistently low, however, levels of cadmium in oysters from a number of areas were above average but did not exceed the Dutch human consumption tolerance value. It is known that oysters accumulate metals more readily than mussels and, considering the remoteness of many of these areas, the elevated cadmium levels are not considered to be anthropogenic in origin.
    • Monitoring of Shellfish Growing Areas - 1995

      Smyth, M; Rowe, A; McGovern, E; Nixon, E (Marine Institute, 1997-08)
      In accordance with the monitoring requirements of the 1979 Council Directive 79/923/EC on the water quality of shellfish waters, water and shellfish samples were collected from 21 major shellfish-growing areas and analysed for physicochemical parameters and chemical contaminants. At each site temperature, salinity, pH and dissolved oxygen measurements were made and the area was inspected for the presence of visible petroleum hydrocarbons. Water samples were collected for suspended solids determinations. A representative sample of the shellfish from each area was collected and returned to the laboratory for metal and chlorinated hydrocarbon analyses. As in previous years, the water quality was good and conformed to guidelines and requirements of the Directive. Petroleum hydrocarbons were not observed in any of the shellfish waters or as deposits on the shellfish. Chlorinated hydrocarbon levels were very low, evidence of the clean, unpolluted nature of Irish shellfish and shellfish-producing waters. Mercury and lead levels were consistently low. Levels of cadmium in oysters from a number of areas were slightly elevated but did not exceed the Dutch human consumption tolerance value of 1mg/kg (ppm) wet weight.
    • Movement of Salmon from the South Coast in 1975

      McCarthy, D T (Department of Agriculture and Fisheries (Fisheries Division), 1977)
      In 1973, tagging investigations commenced into the origin of the salmon stocks being exploited by drift nets along the south coast of Ireland (8º0’W - 10º0’W). The exploitation of these stocks commenced in 1968 with a catch of 1,500 fish and by 1975 the catch had increased to 90,400. The results of the 1973-1974 programme and a description of the fishing methods used have been published in Fishery Leaflet No. 67. Throughout the programme, fish were tagged using Lea’s hydrostatic tags described by Went (1951). A marked difference in returns was observed in 1975 between salmon revived in sea water tanks and those released directly after tagging, In the former, a 14.8% recapture rate was recorded, compared with 6% in the case of salmon released immediately after tagging.
    • Movement of salmon from the south coast of Ireland in 1973-1974

      McCarthy, D T (Department of Agriculture and Fisheries (Fisheries Division), 1975)
      In 1973 tagging investigations were started into the origin of the salmon stocks being exploited in the West Cork area (8º0'W to 10º10'W) along the south coast of Ireland. The vessels used varied from six metre open boats to twenty metre trawlers, the average length was 10.5 metres (1972 survey involving 276 boats). Fishing is carried on over the twenty four hours. Up to 1973 nets were 30 mashes deep: in that year nets of 60 and up to 98 meshes were introduced, and during the 1974 season most boats fished nets of 68 meshes deep. The length of net varied from 400 metres to 1.6 km. Nets were shot at right angles to the coast in roughly a north-south direction, all vessels staying quite close to land, the furthest distance out being approximately 2 km from land. Most fish were caught in the bottom portion of the net during the hours of day-light but at night or in rough weather about half the catch were caught in the top portion of the net.
    • Mulroy Bay Scallop Research 1980

      Griffith, David de G (Department of Agriculture and Fisheries (Fisheries Division), 1981)
      Following a preliminary investigation in 1977, the Department of Fisheries & Forestry carried out an intensive multi-disciplinary survey of Mulroy Bay in the summer of 1978. The results of this "blitz" survey, when evaluated, formed the basis of more extensive research in the North Water during 1979. This North Water programme was expanded in 1980, as part of the Department's contribution to a co-operative research programme on Mulroy Bay organised in conjunction with the National Board for Science & Technology. This included a hydrographic survey, specially commissioned by the Department, to produce a detailed bathymetric chart of the North Water. This was made available free of charge to interested individuals and groups in the locality. The 1980 research results were presented at a seminar in January 1981 at the Department's Fisheries Research Centre, which was organised in order that the data obtained could be discussed and evaluated by the individuals and agencies involved in the field programme. This Fisheries Leaflet is a summary of the papers read at that seminar, by staff of the Fisheries Research Centre.
    • National activities in the field of Aquaculture: Ireland

      Griffith, David de G (ed) (Marine Institute, 1996-05)
      This document was prepared in May 1995 by a group of invited aquaculture experts drawn from the Irish aquaculture industry, the Fisheries Research Centre, An Bord Iascaigh Mhara, Salmon Research Agency, Veterinary Research Laboratory, the Marine Institute and from University RTD laboratories. It was drafted as a contribution to the 1995 meeting of Directors of Fisheries Research Organisations of the European Union, and as a response to a review by DG XIV entitled "European Aquaculture Research: current position and prospects” (COM(94) 258 final).
    • National Survey of the Sea Lice (Lepeophtheirus salmonis Krøyer and Caligus elongates Nordmann) on Fish Farms in Ireland - 2000

      McCarney, P; Copley, L; Jackson, D; Nulty, C; Kennedy, S (Marine Institute, 2001-09)
      Fanned fish can be divided into three distinct groups, rainbow trout and two year classes (or generations) of salmon. In terms of husbandry and lice management, salmon which are at sea for a year or longer in April (growers/one-sea winter) are treated separately from younger salmon (smolts) and rainbow trout. Those salmon that were put to sea in winter 1999/spring 2000 are referred to as smolts, or 2000 year class fish. The farms were inspected twice a month in March, April and May and once a month thereafter, with one exception, December/January where sites were visited only once. Two species of lice are commonly found on cultured salmonids, Caligus elongates Nordmann, a species of parasite that infests over fifty different species of marine fish, and Lepeophtheirus salmonis Krøyer, which infests only salmon and closely related species such as rainbow trout. Lepeophtheirus salmonis, the Salmon Louse, is regarded as the more serious of the two species and occurs most frequently on Irish cultivated salmon (Jackson and Minchin, 1992). Results for both species are given for each sampling period. These sea-lice inflict damage to their hosts through their feeding activity on the host's body (Jones et al., 1990; Jonsdottir et al., 1992; Kabata, 1974) and significant economic losses were attributed to these copepod ectoparasites by Roth et al. (1993). Lepeophtheirus salmonis is a member of the Family Caligidae and has a direct lifecycle (i.e. a single host). This life-cycle comprises ten stages. Following hatching from paired egg strings, two free-living nauplius stages are dispersed into the plankton. These stages are followed by a copepodid stage where contact with the host takes place. The copepodid then moults through four chalimus stages before becoming a pre-adult male or female. This pre-adult phase comprises two stages and is followed by the fully mature adult phase. The adult female can produce a number of batches of paired egg-strings which in turn hatch into the water column to give rise to the next generation (Kabata, 1979; Schram, 1993).
    • National Survey of the Sea Lice (Lepeophtheirus salmonis Krøyer and Caligus elongates Nordmann) on Fish Farms in Ireland - 2001

      McCarney, P; Copley, L; Kennedy, S; Nulty, C; Jackson, D (Marine Institute, 2002-02)
      Two species of lice are found on cultured salmonids, Caligus elongatus Nordmann, a species of parasite that infests over fifty different types of marine fishes, and Lepeophtheirus salmonis Krøyer, which infests only salmon and other salmonids. The Salmon Louse (L. salmonis) is regarded as the more serious parasite of the two species and has been found to occur most frequently on Irish farmed salmon (Jackson and Minchin, 1992). Most of the damage caused by these parasites is thought to be mechanical, carried out during the course of attachment and feeding (Kabata, 1974; Brandal et al., 1976; Jones et al., 1990). Inflammation and hyperplasia (enlargement caused by an abnormal increase in the number of cells in an organ or tissue) have been recorded in Atlantic salmon in response to infections with L. salmonis (Jones et al., 1990; Jonsdottir et al., 1992; Nolan et al., 2000). Increases in stress hormones caused by sea lice infestations have been suggested to increase the susceptibility of fish to infectious diseases (MacKinnon, 1998). Severe erosion around the head caused by heavy infestations of L. salmonis has been recorded previously (Pike, 1989; Berland, 1993). This is thought to occur because of the rich supply of mucus secreted by mucous cell-lined ducts in that region (Nolan et al., 1999). In experimental and field investigations carried out in Norway heavy infestation was found to cause fish mortalities (Finstad et al., 2000). Lepeophtheirus salmonis (Caligidae) has a direct life cycle, meaning it uses a single host. After hatching from the egg (which is extruded from the adult female louse in paired egg strings) two free-living nauplii stages are dispersed into the water column. A copepodid stage then follows during which a host must be located before the parasite can develop further. After finding a host the copepodid moults through four chalimus stages, which all occur while the parasite is attached to the host, before developing into a mobile pre-adult male or female. A moult then separates two pre-adult stages after which the fully mature adult develops. The adult female is capable of producing a number of batches of paired egg-strings during her life-span, which in turn hatch into the water column giving rise to the next generation. This gives a total of ten stages through which the parasite must develop to reach adulthood (Kabata, 1979; Schram, 1993). Caligus elongatus is a non-host specific parasite and can be found on many different fish species (Kabata, 1979). It has a similar life cycle to that of L. salmonis (Hogans and Trudeau, 1989). Four groups of farmed fish were examined during sea-lice inspections in 2001. These include rainbow trout, salmon smolts (200 I generation), one sea-winter salmon (2000 generation) and two sea-winter salmon (1999 generation). S1/2's or half year smolts are fish which are transferred to sea in Autumn/Winter of the same year that they are hatched, they smoltify early due to a photoperiod manipulation (Willoughby, 1999). Their S1 siblings smoltify and are put to sea in early spring. S1/2's are included in each year class of fish for the purpose of analyses.
    • National Survey of the Sea Lice (Lepeophtheirus salmonis Krøyer and Caligus elongates Nordmann) on Fish Farms in Ireland - 2002

      O'Donohoe, P; Kennedy, S; Copley, L; Kane, F; Naughton, O; Jackson, D (Marine Institute, 2003)
      Salmonids farmed in Ireland in 2002 can be divided into the following groups: one year class of rainbow trout Oncorhynchus mykiss and three year classes of Atlantic salmon Salmo safar. The year classes of salmon include, smolts (2002 generation), one sea-winter salmon (2001 generation) and two sea-winter salmon (2000 generation). S1/2' s are fish which are transferred to sea in Autumn/Winter of the same year that they are hatched. Their S1 siblings smoltify and are put to sea in early spring, some three to four months later. Salmon which are at sea for a year or longer in April are known as growers/one sea-winter and are treated separately from younger salmon (smolts) and rainbow trout. Those salmon that were put to sea in winter 200 I /spring 2002 are referred to as smolts, or 2002 year class fish. During the 2002 sampling period all four groups of farmed fish were examined. Two species of sea lice are found on cultured salmonids in Ireland, Caligus elongates Nordmann, a species of parasite that infests over eighty different types of marine fish, and Lepeophtheirus salmonis Krøyer, which infests only salmon and other salmonids. Sea lice are regarded as having the most commercially damaging effect on cultured salmon in the world with major economic losses to the fish farming community resulting per annum (Bristow and Berland, 1991; Jackson and Costello, 1991). They affect salmon in a variety of ways: mainIy by reducing fish growth, loss of scales which leaves the fish open to secondary infections (Wootten et aI., 1982) and damaging of fish which reduces marketability.
    • National Survey of the Sea Lice (Lepeophtheirus salmonis Krøyer and Caligus elongates Nordmann) on Fish Farms in Ireland - 2003

      O'Donohoe, P; Kennedy, S; Kane, F; Naughton, O; Tierney, D; Copley, L; Jackson, D (Marine Institute, 2004)
      Sea lice are regarded as having the most commercially damaging effect on cultured salmon in the world with major economic losses to the fish farming community resulting per annum (Bristow and Berland, 1991; Jackson and Costello, 1991). They affect salmon in a variety of ways; by reducing fish growth; by causing loss of scales, which leaves the fish open to secondary infections (Wootten et al., 1982); and by damaging the fish, which reduces its marketability. The two species of sea lice found on cultured salmonids in Ireland are Caligus elongatus Nordmann, a species of parasite that infests over 80 different types of marine fish, and Lepeophtheirus salmanis Kroyer, which infests only salmon and other salmonids. L. salmonis is regarded as the more serious parasite of the two species and has been found to occur most frequently on farmed salmon (Jackson and Minchin, 1992). Most of the damage caused by these parasites is thought to be mechanical, carried out during the course of attachment and feeding (Kabata, 1974; Brandal et al., 1976; Jones et al., 1990). Inflammation and hyperplasia (enlargement caused by an abnormal increase in the number of cells in an organ or tissue) have been recorded in Atlantic salmon in response to infections with L. salmonis (Jones et al., 1990; Jonsdottir et al., 1992; Nolan et al., 2000). Increases in stress hormones caused by sea lice infestations have been suggested to increase the susceptibility of fish to infectious diseases (MacKinnon, 1998). Severe erosion around the head caused by heavy infestations of L. salmonis has been recorded previously (Pike, 1989; Berland, 1993). This is thought to occur because of the rich supply of mucus secreted by mucous cell-lined ducts in that region (Nolan et al., 1999). In experimental and field investigations carried out in Norway heavy infestation was found to cause fish mortalities (Finstad et al., 2000).
    • The Parasitology of Irish Mussels

      Crowley, M (Department of Agriculture and Fisheries (Fisheries Division), 1972)
      Investigations of the distribution of three parasites of mussels, an internal copepod parasite of the gut (Mytilicola intestinalis), an external decapod parasite in the gill region (Pinnotheres pissum) and an analid shell parasite (Polydora ciliata) were carried out from October 1971 to April 1972. Samples from 26 locations around the Irish coast were investigated. One hundred mussels from each sample were weighed, measured in 5 mm groups, boiled and the following were estimated as percentages of the whole mussel:- a. Shell; b. Meat; and c. Loss.