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Recent Submissions

  • 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.
  • Exploitation and Survival of River Shannon Reared Salmon

    O'Maoileidigh, N; Browne, J; McDermott, T; Cullen, A; Bond, N; McEvoy, B; O'Farrell, M; O'Connor, W (Department of the Marine, 1994)
    Following the construction of the River Shannon hydroelectric scheme the Electricity Supply Board (ESB) have maintained a juvenile salmon restocking programme. Tagging of smolts with coded wire tags (microtags) was initiated in 1980 to examine the migration and survival of these stocked fish. In 1991, an estimated 292,000 hatchery reared salmon smolts (micro tagged and adipose finclipped) migrated from the River Shannon, County Limerick. This allowed an assessment to be made of the contribution of these fish to the high seas fisheries at West Greenland and Faroes, and also to homewater net and rod fisheries. Over 12,000 grilse from this release programme were estimated to have been taken by commercial nets with 525 taken on rods and 3,147 surviving to spawn. The return rate of 2 sea winter fish was much lower with 150 taken by commercial nets, 93 taken by rods and 202 estimated to have spawned. The Greenland fishery took approximately 107 potential 2 sea winter fish which is a high proportion of the overall 2 sea winter stock. Tag returns from groups of smolts released by helicopter proved to be highest. Groups released above the dams and which had to navigate through these installations also showed comparatively good returns. Early presmolt and smolt releases (i.e. December and February) did not give as good return rate in comparison to the other release groups.
  • Exploitation and Survival of Reared Salmon Released into the Burrishoole River System

    O'Maoileidigh, N; Browne, J; Cullen, A; McDermott, T; Keatinge, M (Department of the Marine, 1994)
    Hatchery reared salmon smolts have been microtagged using binary coded nose tags and released into Irish rivers since 1980. These tagged fish are intercepted and identified in high seas coastal fisheries and in Irish rivers as adult salmon. The tag recovery programme provides valuable information on the marine survival and exploitation rates of these tagged fish and the return rates back to the river of origin. This leaflet summarises the results for release groups of reared indigenous salmon from the Burrishoole system in Co. Mayo. Marine survival prior to homewater exploitation has been very variable in the period examined. Although homewater marine exploitation rates have varied considerably depending on the fishing areas, they remained high for all areas combined between the years 1982 to 1989 with exploitation rates by coastal fisheries up to 87%. The greater part of the catch is taken in the Mayo area. Exploitation rates have decreased since 1989 and approximately 60% of the returning stock is estimated to have been caught in coastal fisheries in 1993. Survival to the river has also varied with an average of 2.5% of the total number of smolts released returning as adults to the river.
  • Fish Kills in Ireland in 1993

    Moriarty, C (Department of the Marine, 1994)
    The pattern of fish kills in 1993 showed a dramatic change from that of the previous ten years. The number of incidents showed a very welcome reduction to a total of 33, the lowest since systematic records began to be kept in 1982. Only one case of damage caused by silage effluent was reported and two from farm effluents - in the recent past these were the most frequent and serious sources. However, fish kills provisionally attributed to 'enrichment' attained a record total of 16, most of them in the lakes in Co. Cavan in the Erne catchment. Sewage and runoff from agricultural land are the main sources of the phosphorous which brings about excessive blooms of microscopic algae. Enrichment has caused extremely serious problems in the past, in particular in Loughs Ennel and Sheelin. In both cases, remedial measures were successful, although problems have arisen again in the case of Lough Sheelin. The more widespread problem in the Erne catchment may be more difficult to contain and there are also signs of trouble in the Rivers Shannon and Lee. The trend of increasing numbers of enrichment-based fish kills does not necessarily mean that even more such incidents will take place in 1994 - but it is virtually certain that similar problems to those of 1993 will arise sooner or later unless action is taken.
  • Fish Kills in Ireland 1991-1992

    Moriarty, C (Department of the Marine, 1993)
    The numbers of fish kills were below the average for the ten years since the systematic recording of incidents began in 1983. Totals were 60 and 51 for 1991 and 1992 respectively. Both years therefore represent a continuation of the downward trend which began after the peak of 122 incidents in 1987. An important factor in the improved situation was the reduction in the number of silage discharges which had been the most serious problem for a number of years. Untreated sewage and industrial effluents in general have also shown downward trends. . Two serious problems remaining are 'enrichment' and run-off from farmyards, which includes spillage of slurry. Slurry and farm effluents in fact showed an increase in 1992 over 1991. Enrichment by excessive phosphorous, derived both from partially treated domestic sewage and from fertiliser, causes algal blooms leading to deoxygenation of the water and the death sometimes of very large numbers of fish - to say nothing of environmental conditions which are unacceptable to everybody who uses rivers or lakes. The effect of a discharge of effluent depends on many factors. In wet weather with high stream flows the damage will be minimised because the effluent is diluted quickly. A spillage beside a small river will led to a much more extensive fish kill than the same quantity of effluent will cause in a large one. These and other factors probably explain why, in spite of the small number of fish kills in 1992, nearly twice as much river was affected as in 1991.
  • Contaminants in marine biota 1990 monitoring programme

    Nixon, E R; McLaughlin, D; Boelens, R G; O'Sullivan, G (Department of the Marine, 1991)
    In 1990, samples of fish from commercial catches landed in Ireland, and fish and shellfish collected at Irish coastal sites, were analysed in accordance with the requirements of the Joint Monitoring Programme (JMP) of the Oslo and Paris Commissions (OSPARCOM). The methodologies employed were consistent with JMP Purpose A: Significance to human health, and JMP Purpose C: Existing geographical distributions. The levels of heavy metals and chlorinated hydrocarbon compounds were generally low: well below the internationally accepted levels for protection of human health, and below the levels known to be of significance to marine life. Higher than Irish average levels were found in areas such as Dublin Bay, Cork Harbour, Mornington on the river Boyne, and the Barrow and Rogerstown Estuaries. These are all adjacent to densely populated and industrialised catchments and coasts. There were no cases of serious contamination.
  • Fish Kills in Ireland in 1989

    Moriarty, C (Department of the Marine, 1990)
    The final estimate for the number of fish kills in 1989 was 111. The increase in 1989 is largely accounted for by the exceptional warm weather conditions which prevailed. Details of all the incidents are given in the following pages. When these are analysed some very significant facts emerge. The number of fish kills while higher than in 1988 (50 kills) was about nine percent lower than in 1987 (122 kills). Low water due to dry weather conditions was the most important factor in 1989 raising the number of kills by 50%. Despite weather conditions, fish kills due to agricultural causes showed little change on the 1988 level - thus maintaining the substantial reduction in kills due to these causes achieved in 1988. As many as 50 of the incidents resulted from pollution which in a normal wet summer would not have caused such serious damage. These problems give a useful, if painful, reminder that water pollution can have devastating results. They also serve to highlight high risk situations. Many of the 1989 fish kills resulted from a shortage of oxygen from untraceable causes, for example from excessive plant growth due to fertiliser run-off or domestic sewage - or both. Others came from identifiable sources. In about half these cases the authorities felt that genuine accidents had happened and a warning to the guilty party was all that was needed. In others, twenty-seven in all, legal proceedings were set in motion.
  • Fish Kills in Ireland in 1988

    McCarthy, D; Moriarty, C (Department of the Marine, 1989)
    The number of fish kills reported in 1988 showed a very welcome reduction to 50 incidents after the 1987 record of 122. The principal source of trouble has continued to be inadequately planned agricultural practices. Run-off from silage was once more the most serious problem, accounting for 13 kills. Slurry or manure accounted for seven more. While weather conditions may have alleviated the problem, due credit for the improvement must be given to the farmers who responded to the campaign organised by the Government in conjunction with the farming organisations. Industrial sources were responsible for 11 incidents. They have been increasing since 1985 but still remain below the maximum recorded in 1984. Sewage, for the first time since 1980, was not implicated. The most serious events in 1988 were on the Inny caused by an industrial effluent and on the Dodder following a discharge of silt from a water treatment plant.
  • Fish Kills 1969-1987

    McCarthy, D T (Department of the Marine, 1988)
    A total of 66 fish kills were reported to the Regional Fisheries Boards in 1986 and 122 in 1987. Effluents from agriculture and agriculture-based industries accounted for 56 of the kills in 1986 and 95 in 1987. When the two periods, 1969-74 and 1980-87 are compared, it can be seen that the numbers caused by sewage and industrial wastes have not changed significantly, but the damage from agriculture has risen at an alarming rate. The fact that problems from sewage and industry remained at a low level in the period, in spite of increasing urbanisation, suggests that measures to combat these sources of pollution have had some effect. Analysis of the fish kills shows clearly that the most urgent problem is to discover how silage effluent can be controlled.
  • The Eel Stocks of the Shannon System and Prospects for Development of the Fishery

    Moriarty, C (Department of the Marine, 1987)
    Lough Neagh has long been known to yield the greatest quantities of eels of any water body in Ireland, the annual catch being in excess of 700 tonnes. The Shannon catchment on the other hand yields less than 100 tonnes per annum. This Leaflet describes work carried out in Lough Neagh and in the Shannon catchment in 1985 and 1986 which has indicated that eels are now more abundant in the Shannon System than in Lough Neagh. The implications are that the stocks in the Shannon System are sufficient to yield an annual catch of as much as 1,000 tonnes and value £2 million. The current capital cost of establishing a two-man crew capable of catching 3 tonnes of eel, value £6,000, is £2,500. Annual running costs per crew are less than £1,000. The large scale exploitation of the fishery would involve much more substantial investment by the owners. Arising from this paper, the Department has raised the matter with the ESB and the Shannon Regional Fisheries Board to agree on a strategy to maximise employment from the fishery.
  • Results of Magnetic Tag Recovery Programme in the Mayo Area in 1986

    Gallagher, P; Browne, J (Department of the Marine, 1987)
    Young salmon are tagged at various locations throughout the country with coded wire tags. They are released at different times of the year, and in various river systems to establish the best time of year and the best locations for release. The majority of the tagged fish are hatchery reared, the only exception being in the Corrib and Blackwater rivers where wild smolts are tagged. All micro-tagged fish are adipose fin clipped. Some hatcheries also use an adipose fin clip to mark their reared fish. Twenty nine thousand net caught salmon were examined at a number of locations in Mayo. All fish with adipose fin clips were screened with a magnetic tag detector. A total of 736 tags were recovered from which it was estimated that rearing stations contributed over 1,300 fish to the north Mayo catch.
  • Profile of the Caragh, County Kerry: A Salmonid Producing Catchment

    Fahy, E (Department of Tourism, Fisheries and Forestry, 1987)
    From the mid 1960s competition for Atlantic salmon intensified with the expansion of high seas fisheries in the marine sub-Arctic and drift-netting closer to home. Inshore commercial fishermen and freshwater anglers saw progressively more of the salmon stock being landed outside its river of origin which prompted some to seek an alternative game species. Sea trout, which have traditionally been a by-catch of the commercial salmon fishery and which game fishermen valued, were considered and various clubs and individuals (fishery owners and managers) addressed queries to the Department responsible for fisheries on the possibility of developing a sea trout run to supplement a declining salmon population. The majority of queries examined by this writer concerned the introduction of sea trout to parts of river systems outside their normal range. A review of sea trout distribution (Fahy, 1977) described their migratory limit inland and contained adequate information to assess the suitability of the majority of fresh water bodies for the fish. The Caragh (Glencar) catchment was more intriguing. There are now in existence many investigations on the inter-relationships of salmonid species in fresh water and on their interactions with their environment but there are few specific references to the suitability of catchments for particular species. This investigation examines a case in point.
  • Populations Estimates of Juvenile Salmon in the Corrib System from 1982 to 1984

    Browne, J; Gallagher, P (Department of Tourism, Fisheries and Forestry, 1987)
    This leaflet gives the details of juvenile salmonid densities for the years 1982 to 1984 in the Corrib system. In general, since these investigations began in 1979, the Corrib tributaries have appeared to be adequately stocked with salmon. The salmon densities in the rivers to the west of Lough Corrib are much higher than in the rivers to the east. However, survival is higher in the latter. A detailed survey of juvenile salmon habitat revealed that there are 392,000 square metres of suitable habitat in the system. Of this 253,000 square metres are on the west side and 139,000 on the east side.
  • Results of Magnetic tag Recovery Programme in the Mayo Area in 1985

    Gallagher, P (Department of Tourism, Fisheries and Forestry, 1986)
    This leaflet deals with the results of the magnetic tag recovery programme for the Mayo area in 1985. The commercial salmon catch was sampled for adipose fin clipped and micro tagged fish at a number of locations in Mayo. All fish with adipose fin clips were screened with a magnetic tag detector for tags, and the tags were read to establish the origin of the fish. Fish are tagged at various locations throughout the country with magnetic wire tags. These tagged fish are released at different times of the year, and in various river systems to establish the best time of year to release fish and the best locations. The majority of all the tagged fish are hatchery reared, only in the Corrib river are wild fish tagged.
  • Interaction between seals and salmon drift net fisheries in the west of Ireland

    McCarthy, D T (Department of Fisheries and Forestry, 1985-05)
    The common seal Phoca vitulina L. and the grey seal Halichoerus grypus F. are both present in colonies along the west coast. The common seal inhabits bays and estuaries and inlets with sandy bars mainly in Galway Bay, Clew Bay, Co. Mayo, Ballysadare Bay, Co. Sligo and Donegal Bay. The grey seal is more widely dispersed particularly in the summer months and can be seen in bays, estuaries and offshore islands. Widespread complaints by salmon fishermen in Galway Bay of severe predation by seals on salmon caught in drift nets in 1978 led to a programme to study the problem. In 1979 and 1981 direct observations on board two salmon drifters were made in Galway Bay and in 1980 and 1981 similar work took place on three boats in Sligo Bay. In addition, two crews were interviewed in port each evening. In 1980 salmon landed in Donegal, Galway and Kenmare were examined at market points and the number of seal damaged fish recorded. This leaflet gives the results of the study and concludes that effective control requires measures against the seals which are actually robbing the nets. Destruction of seals at breeding colonies is unlikely to have any positive effect on the rate of predation.
  • The Impact of Eel Fyke Netting on Other Fisheries

    Moriarty, C (Department of Tourism, Fisheries and Forestry, 1986)
    The small fyke net was introduced to Ireland in 1963 and has been operated extensively in tidal water ever since. Experiments in freshwater began in Lough Corrib in 1967, conducted by the then Department of Agriculture and Fisheries. In 1970 operation by professional fishermen under special authorisations began. It has been effectively demonstrated by the Department's experiments, by information furnished by the professional fishermen and by observations by local fishermen and the Department's officials that fyke nets could be used for eel fishing without harmful effects on other fish stocks. As a result, the fyke net was listed as a "scheduled engine" in the Fisheries Act, 1980
  • Surveys for herring larvae off the northwest and west coasts of Ireland in 1982 and 1983

    Grainger, R; McArdle, E (Department of Fisheries and Forestry (Trade and Information Section), 1984)
    This Leaflet describes the methods used in sampling and gives the results of the 1982 and 1983 surveys in a series of maps showing the distribution of the young larvae. Sampling took place at fortnightly intervals and recorded the numbers of larvae in three size groups. The area of operation extended from Inishowen Head to Loop Head and thus includes the entire new assessment area for this herring stock. It was first surveyed for herring larvae in 1981 (see Fisheries Leaflet 117). As in1981, these surveys showed spawning to move progressively southwards during the season in October and November. There are three main spawning areas: the north Donegal coast, the west coast of Donegal and the west coast of Mayo. Larval abundance was over 10% higher in 1983 than in 1982. When the survey has been in progress for a few more years it will be possible to make an improved annual assessment of the herring stock in the region. This can be used by management to ensure that the fishery is exploited to the fullest extent without risk of damage to the stocks in the future.
  • The Sea Trout Year 1983

    Fahy, E (Department of Fisheries and Forestry (Trade and Information Section), 1984)
    Climatic conditions favourable to sea trout production did not improve in 1983 and juvenile output from freshwater was poor. Several years of a reduced smolt exodus have resulted in the stocks being depleted of older fish and a large proportion of the 1983 landings consisted of post-smolt (finnock). The mean smolt age has been tending upwards so that the prospect for "specimen" sea trout in the future is not good. In spite of the depleted recruitment of the past few years the yield from sea trout fisheries has remained fairly constant: the estimated total catch between 1980 and 1982 varied from 49.4 to 59.3 tonnes. A steady catch total against a background of fluctuating recruitment is due to two factors: first, the catch being a small proportion of the stocks and second, the fact that sea run trout make a divided return to fresh water.
  • Have Hatcheries a Role in Sea-Trout Management?

    Fahy, E (Department of Fisheries and Forestry (Trade and Information Section), 1983)
    The artificial propagation of sea trout in Ireland has a long history but the fish were never produced in large numbers and they were disposed of at an early stage in development. The evidence suggests that artificial propagation was undertaken as a by-product of salmon management. The circumstances in which artificial propagation of sea trout may be justified are examined and some general reservations are expressed. For the future it seems likely that sea trout will be exploited in wild rather than in put-and-take fisheries. The emphasis should remain on providing the most suitable nursery conditions for the fish to reproduce naturally. Further investigations should however be undertaken on devising suitable methods of propagating sea trout and consideration might be given to re-establishing some of the long lived strains which are now believed to be extinct.
  • The Sea Trout Year, 1982

    Fahy, E (Department of Fisheries and Forestry (Trade and Information Section), 1983)
    The large juvenile trout exodus from fresh water to the sea which occurred in 1981 was not repeated in 1982. Climatic indicators suggest alternately good and poor years in the output of juvenile fish with a reduced recruitment to the fishery in the immediate future. The mean smolt age is likely to rise and the consequences of this will most likely be a reasonable post-smolt (or finnock) run and a diminution in the contribution of larger sea trout to the catch. Added to the poor run of exploitable fish in 1982, the angling season was curtailed by very dry weather which reduced effective fishing effort. In spite of this, yield per rod licence was almost identical to that in the previous year. However figures for the fishery districts suggest that fewer sea trout were captured. Draft net catches were up on those of 1981 by 68%. This had been anticipated in Fisheries Leaflet number 116 which suggested that trout from the larger juvenile exodus of 1981 would become exploited as one sea winter fish by this method: the recorded increase in the catch was almost certainly promoted by dry summer weather which confined sea trout to the estuaries. Both draft and drift net sea trout catches constituted a higher proportion of the salmon net catch in. 1982 than in 1981. The latter showed a marked reduction on the previous year but this evaluation of the data does not include returns from the Western and particularly the Northern fisheries regions where the salmon catch was said to be high.

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