• Studies of the Eel Anguila Anguila in Ireland

      Moriarty, C. (Department of Agriculture and Fisheries [Fisheries Division], 1972)
      A total of 1,722 immature eels of lengths 25 to 95 cm and ages 5 to 33 years were collected in summer by fyke netting. It was shown that migration upstream was very slow, few eels of less than 9 years old being found upstream of Lough Corrib. Eels of less than 50 cm fed mainly on invertebrates, larger individuals brcoming piscivorous. Differences in the diets in the various lakes were observed and some evidence of selective feeding was found.
    • Studies of the Eel Anguila Anguila in Ireland No. 2. In Lough Conn, Lough Gill, and North Cavan Lakes

      Moriarty, C. (Department of Agriculture and Fisheries [Fisheries Division], 1973)
      A total of 843 immature eels of length 27 to 86 em and ages 5 to 28 years were collected in summer by fyke netting. The North Cavan eels formed a distinct population of large, fast-growing eels, most of which matured before 12 years. The eels of the other lakes were slower in growth and in maturing, substantial numbers of 13 years and older being found. Principal food organisms in the Cavan eels were fish and chironomid larvae; in Lough Gill fish for eels of over 50 cm and Gammarus and Ephemeroptera larvae for smaller; in Lough Conn, Gastropoda for all sizes.
    • Studies of the Eel Anguila Anguila in Ireland No. 3. In the Shannon Catchment

      Moriarty, C. (Department of Agriculture and Fisheries [Fisheries Division], 1974)
      A sample of 1,637 immature eels of length 28 to 91 em and age 5 to 26 years was collected in summer seasons from 1969 to 1973 by fyke netting. The growth rate was similar to that of eels in many other Irish lakes but the age at maturity in the eels of the main Shannon was several years more than in similar waters. The food was almost exclusively invertebrate. In the Fergus system lakes earlier maturity was noted and fish was the principal food of eels of over 50 cm. A preliminary study of eels migrating upstream at Parteen Weir in 1973, 15 km above the tidal boundary, showed that few, if any, elvers travelled that distance in their first year.
    • Studies of the Eel Anguila Anguila in Ireland No. 4. In the Munster Blackwater River

      Moriarty, C. (Department of Agriculture and Fisheries [Fisheries Division], 1974)
      Yellow eels from estuarine and freshwater populations were sampled by fyke netting: in 1965 and 1966 2,221 specimens from the estuary and in 1972 and 1973 826 specimens from freshwater. It was the first extensive study of eels in an Irish river and the population was found to be more dense than that recorded in lakes. Growth in the estuary was relatively fast and spawning migration began at 9 years while in the freshwater growth was slower and migration began about four years later. One specimen of 36 years old was found and more than 17% of the freshwater sample were over 19 years. Eels of less than 40 cm fed largely on invertebrates whereas eels of 50 cm and over fed mainly on fish, cyprinids being taken to a much greater degree than salmonids. It was calculated that fyke netting of the unexploited fishery could yield a catch of 21 tonne of eels of over 50 em length in the lowland freshwater portion of the river.
    • Studies on Dublin Bay Prawns (Nephrops norvegicus) in the Irish Sea

      Hillis, J P (Department of Agriculture and Fisheries (Fisheries Division), 1971)
      The fishery for Dublin Bay prawns (Nephrops norvegicus) is carried on in a number of areas around the coast of Ireland, but the bulk of the catch comes from the Irish Sea north of Dublin, where the greatest landings, excluding County Down, are at Skerries, It is of recent origin, having been negligible prior to 1955, since when it had risen with some fluctuations to nearly 18,000 cwt in Counties Dublin and Louth in 1968. In research on prawns, there is no known means of ageing the animals, which makes estimates of their mortality and growth rate difficult. Sampling is complicated by the fact that they make burrows in the sea bed, into which they retreat when conditions are not suitable, thus sometimes giving small catches on grounds where the population may be large. This activity is governed by light conditions and the strength of bottom currents. In addition, females carrying external eggs disappear from the catch soon after becoming buried, due to either burrowing or emigration - most research workers believe the former to be the case. Work carried out in 1968 included:- (i) a survey of the commercial catch to find the size of prawns marketed and of those discarded at sea in order to compare their sizes with those taken in former years and (ii) with the aid of the research vessel, Cú na Mara, a comparison of the numbers, average size and sex-ratio of prawns from different depths and at different times of day. The aim of this research programme is to ascertain the facts governing the reproduction, growth rates and economic yield of this important stock of prawns.
    • Studies on the Minnow Phoxinus Phoxinus (L.) from an Upland Irish Reservoir System

      Dauod, H. A.; Bolger, T.; Bracken, J. J. (Department of Agriculture and Fisheries [Fisheries Division], 1985)
      The paper deals with the population structure and biology of the minnow, Phoxinus phoxinus (L.), in the Roundwood Reservoir system. A total of 4,342 minnow were taken during the study period from three locations, 2,796 fish were used to calculate the age distributions and 3,013 were examined for gut contents. The age data, determined from the otoliths, showed that there are five age classes present. The mean length at the end of the first year (O-Group fish), was 3.41 cm, at the end of the second year (I-Group fish) it was 5.32 cm and 6.68 cm at the end of the third year (II-Group). Only thirteen minnow were found to be older than three years. The breeding season is later than normal and peaks in August and September. Sexual maturity is reached by the majority in their second year and all older fish are mature. Egg diameters were shown to be smaller than for fish from midland Irish waters. In the North and South Lakes the dominant food organisms were found to be chironomid and trichopteran larvae, molluscs and Cladocera. The diet of the fish from the Vartry River contained more ephemeropteran nymphs. Seasonal differences in the diet are noted. The influence of the minnow on the associated fish species is discussed. An account of the distribution of the minnow in Ireland is included as an Appendix.
    • Studies on the Three-Spined Stickleback Gasterosteus aculeatus L. from an Upland Irish Reservoir System

      Dauod, H. A.; Bolger, T.; Bracken, J. J. (Department of Agriculture and Fisheries [Fisheries Division], 1985)
      Monthly samples were taken using a small-meshed beach seine. A total of 1092 sticklebacks were captured, 725 fish were used to calculate the age distributions and 699 were examined for gut contents. The age data, determined from the otoliths, showed that there were four age classes present. The mean length of first year fish (O-Group fish) was 2.24cm, of second year fish (I-Group) 3.36 and 4.47cm and 5.72cm for II-Group and III-Group fish respectively. The breeding season was June-July. Sex ratios were similar in both lakes and did not differ significantly from 1 : 1. Sexual maturity was reached by all fish above 3cm. The smallest maturing virgin was 2.6cm in length. Egg diameters varied between 1.0 and 1.5mm. The diet was similar in the two lakes studied. In the North Lake Cladocera, chironomid larvae, copepods and molluscs dominated while in the South Lake Cladocera, copepods, chironomid larvae and surface insects were dominant. Sticklebacks were extremely scarce in the Vartry River and feeder streams entering both lakes and would not pose a threat to egg production by trout and minnow in these streams. The influence of sticklebacks is discussed in relation to other fish species.
    • Study of Brominated Flame Retardants in Irish Farmed Salmon

      Marine Institute (Marine Institute, 2004)
      The Marine Institute (MI) undertakes monitoring and research relating to contaminants and chemical residues in Irish fisheries products, and works with key agencies such as the Food Safety Authority of Ireland (FSAI) to ensure a high level of consumer protection. In 2004 the MI carried out a study of levels of brominated flame retardants, (BFRs), in Irish farmed salmon.
    • A Study of Selected Maërl Beds in Irish Waters and their Potential for Sustainable Extraction

      De Grave, S; Fazakerley, H; Kelly, L; Guiry, M D; Ryan, M; Walshe, J (Marine Institute, 2000)
      Although maërl beds are both of economic importance and conservation interest, data on the distribution of beds and their associated communities are lacking in Irish waters. This report describes the spatial distribution and volume of the maërl resource (Lithothamnion corallioides, Phymatolithon calcareum) along the west coast of Ireland from Donegal to Cork. Taking an average thickness of 2m (range: 0.1 – 3m) the current study estimates that the total national exploitable maërl bearing resource is of the order of 3 x 10^6 metres cubed. The Report outlines guidelines for the exploitation of this natural resource, which because of its extremely low growth rate, cannot be considered a renewable resource in the strictest sense.
    • A study of some invertebrate resources within Bertrabouy Bay, Connemara

      Minchin, D (Department of Agriculture and Fisheries (Fisheries Division), 1975)
      This study of invertebrates in Bertrabouy bay was a by-product from an investigation of the distribution of escallops in Connemara examined by SCUBA diving and dredging. The bay is about 5 miles by 2 miles and has many small inlets and islands; it deepens to 18 fathoms near its entrance. Most of the escallops and lobsters are fished from the centre of the bay to its entrance. Small populations of escallops are fished with hand nets at the head of the bay where oysters were once cultivated on banks that are often covered with eelgrass. Cluaisíns are picked from the banks and winkles are found intertidally throughout the bay. In the course of the study an unexploited lobster population was discovered at the centre of the bay. Crawfish are taken at the bay entrance where razorfish and otter clams are also found. The oyster banks could be examined for future development and the use of a portable shellfish harvester to collect razorfish might be investigated.
    • Summary of the 1st Annual Biodiscovery Research Workshop

      O'Toole, M. J. (Marine Institute, 2010)
      This publication presents the background and aims of the inaugural Marine Biodiscovery Workshop 2008. Presentations relating to progress achieved in the marine biodiscovery research area through the Irish Beaufort Marine Biodiscovery Research Awards have been captured in extended abstracts.
    • Summary Report on 2015 Residue Monitoring of Irish Farmed Finfish and 2015 Border Inspection Post Fishery and Fishery Product Sample Testing

      Residues Monitoring Programme, Chemistry Section, Marine Environmental Food Safety Services (Marine Institute, 2017)
      On behalf of the Department of Agriculture, Food and Marine (DAFM), the Marine Institute carries out monitoring of chemical residues in finfish for aquaculture sector. This monitoring is set out in the annual National Residue Control Plan, which is approved by the European Commission, and is an important component of the DAFM food safety controls and is implemented under a service contract with the Food Safety Authority of Ireland. Since 1999, the Marine Institute has implemented the National Residues Monitoring Programme for aquaculture. This is carried out on behalf of the Sea Fisheries Protection Authority, which is the responsible organisation for residue controls on farmed finfish. The outcome for residues levels in farmed finfish during 2015 remains one of consistently low occurrence. In 2015, in excess of 676 tests and a total of 1,845 measurements were carried out on 128 samples (i.e. 124 target samples & 4 suspect samples) of farmed finfish for a range of chemical substances, including banned and unauthorised substances, various authorised veterinary treatments and environmental contaminants.
    • Summary Report on 2016 Residue Monitoring of Irish Farmed Finfish and 2016 Border Inspection Post Fishery Product Testing undertaken at the Marine Institute

      Marine Institute (Marine Institute, 2018)
      On behalf of the Department of Agriculture, Food and Marine (DAFM), the Marine Institute carries out monitoring of chemical residues in finfish for aquaculture sector. This monitoring is set out in the annual National Residue Control Plan, which is approved by the European Commission, and is an important component of the DAFM food safety controls and is implemented under a service contract with the Food Safety Authority of Ireland. Since 1999, the Marine Institute has implemented the National Residues Monitoring Programme for aquaculture. This is carried out on behalf of the Sea Fisheries Protection Authority, which is the responsible organisation for residue controls on farmed finfish. The outcome for residues levels in farmed finfish during 2016 remains one of consistently low occurrence. In 2016, in excess of 691 tests and a total of 1,933 measurements were carried out on 136 samples (i.e. 126 target samples & 10 suspect samples) of farmed finfish for a range of chemical substances, including banned and unauthorised substances, various authorised veterinary treatments and environmental contaminants.
    • Summary Report on 2017 Residue Monitoring of Irish Farmed Finfish and 2017 Border Inspection Post Fishery Product Testing undertaken at the Marine Institute

      Marine Institute (Marine Institute, 2018-11-27)
      On behalf of the Department of Agriculture, Food and Marine (DAFM), the Marine Institute carries out monitoring of chemical residues in finfish for aquaculture sector. This monitoring is set out in the annual National Residue Control Plan, which is approved by the European Commission, and is an important component of the DAFM food safety controls and is implemented under a service contract with the Food Safety Authority of Ireland. Since 1999, the Marine Institute has implemented the National Residues Monitoring Programme for aquaculture. This is carried out on behalf of the Sea Fisheries Protection Authority, which is the responsible organisation for residue controls on farmed finfish. The outcome for residues levels in farmed finfish during 2017 remains one of consistently low occurrence. In 2017, in excess of 775 tests and a total of 2,250 measurements were carried out on 141 samples of farmed finfish for a range of chemical substances, including banned and unauthorised substances, various authorised veterinary treatments and environmental contaminants.
    • Summary Report on 2018 Residue Monitoring of Irish Farmed Finfish & 2018 Border Inspection Post Fishery Product Testing undertaken at the Marine Institute

      Glynn, D.; McGovern, E.; Kelly, C.; Moffat, R.; Farragher, E. (Marine Institute, 2019)
      On behalf of the Department of Agriculture, Food and Marine (DAFM), the Marine Institute carries out monitoring of chemical residues in finfish for aquaculture sector. This monitoring is set out in the annual National Residue Control Plan, which is approved by the European Commission, and is an important component of the DAFM food safety controls and is implemented under a service contract with the Food Safety Authority of Ireland. Since 1999, the Marine Institute has implemented the National Residues Monitoring Programme for aquaculture. This is carried out on behalf of the Sea Fisheries Protection Authority, which is the responsible organisation for residue controls on farmed finfish. In 2018, in excess of 920 tests and a total of 2,611 measurements were carried out on 171 samples of farmed finfish for a range of residues. Implementation of the Aquaculture 2018 Plan involves taking samples at both farm and processing plant: • 123 target samples taken at harvest: 110 farmed salmon and 13 freshwater trout. • 48 target samples were taken at other stages of production: 40 salmon smolts and 8 freshwater trout. All 2018 samples were compliant. For target sampling of farmed fish, a summary table of the residue results from 2005 - 2018 is outlined in Table 1. Overall, the outcome for aquaculture remains one of consistently low occurrence of residues in farmed finfish, with no non-compliant target residues results for the period 2006-2014, 0.11% and 0.10% non-compliant target residues results in 2015 and 2016 respectively and no non-compliant target results in 2017 and 2018.
    • The Summer herring fishery in the Irish Sea in 1974

      Molloy, J (Department of Agriculture and Fisheries (Fisheries Division), 1975)
      In 1974 the landings of herrings taken by the Irish fleet from the summer herring fishery in the north western part of the Irish Sea increased considerably and were valued at over £277,000. The fishery is based on two different races of herring each having different spawning areas. At present, both stocks are rather small and catches are dependant to a large extent on the influx of young fish each summer. In this situation controls are necessary to prevent the over-exploitation of the adult stock and certain conservation measures are suggested. The operating expenses of boats in this fishery could be reduced considerably by co-operation in the transport of catches from the fishing grounds to the home ports.
    • Supplement to List of Irish Fishes

      Went, A E J (Department of Agriculture and Fisheries (Fisheries Division), 1973)
      In 1969 Dr, M, Kennedy of the Inland Fisheries Trust Inc, and I compiled a List of Irish fishes, which was published by the National Museum, Dublin. This List gave details of the authentic captures of fishes in Irish waters of less than 100 fathoms up to 1968. Since that time three annual lists of rare or interesting fishes from Irish waters have been published in the Irish Naturalist’s Journal (Went, 1970, 1971 and 1972). Details of the fish taken in 1972 will eventually be recorded in an annual list in The Irish Naturalist's Journal. In addition Dunne (1972) has given a list of fishes taken in Galway Bay and adjacent areas. These further captures of interesting species arc summarised in this Leaflet. The order of the species described is that given in the List to which reference should be made for details of captures prior to 1969. Unless stated otherwise all the fish in question were taken in trawls.
    • Surface Temperature Observations at Coninbeg Lightship on the South Coast of Ireland

      Farran, G. (Conseil International pour l'Exploration de la Mer (ICES), 1939)
    • A survey by hydraulic dredge of interstitial bivalves with commercial potential in Cill Chiaráin and Beirtreach buí Bays and along their connecting shoreline, Co Galway

      Fahy, E.; Carroll, J.; Browne, R.; Ní Rathaille, A.; Casburn, P.; Breathnach, S.; Norman, M.; Stokes, D. (Marine Institute, 2002)
      The shellfish co-operative, Comharchuman Sliogéisc Chonamara Teó (CSC) manages oyster and scallop in Beirtreach buí and Cill Chiaráin Bays, both of which are designated aquaculture areas. Cill Chiaráin is also a candidate Special Area of Conservation (cSAC). Various traditional fishing activities are carried on in the bays and CSC has rights to exploit clam species there. The work described here is a survey of interstitial clam species by hydraulic dredge between November 2001 and January 2002. Investigations were restricted from some of the upper bay areas where surface bivalve management was in progress. Much of the remaining areas within the Bays proved unsuitable for hydraulic dredging by virtue of the nature of the substratum. The exposed parts of the lower bays and the intervening coastline where the substratum was coarse sand (maërl or shell sand) were suitable for hydraulic dredging but bedrock and loose boulders often proved obstacles to towing. There was evidence of two assemblages of bivalves in the bays: one typified by Venus verrucosa, Venerupis senegalensis and Tapes rhomboides, all large and potentially valuable, occurred within maërl mixed with fine mud, the other whose most valuable components included Ensis arcuatus and Spisula solida, occurred in disintegrating maërl and in shell sand. The bivalve fauna in the two bays appeared to be typified by relatively high diversity and low biomass – which is accentuated by recent natural mortalities of Ensis arcuatus, a dominant species - and this is likely to prove a challenge to marketing; the Irish market typically exploits small numbers of clam species simultaneously. The terms of the licence under which CSC operates may provide opportunities to exploit clams within their designated area by means other than hydraulic dredging and these should be investigated. In view of the scientific values of the area and its status as a cSAC any plan to exploit its interstitial bivalves should be discussed with the relevant state agency.
    • A Survey of Bottlenose Dolphins (Tursiops truncatus) in the Shannon Estuary

      Rogan, E; Ingram, S; Holmes, B; O'Flanagan, C (Marine Institute, 2000)
      The bottlenose dolphin Tursiops truncatus is a ubiquitous species found throughout the temperate and tropical oceans of the world. The bottlenose dolphin population that occurs in the Shannon is one of only six known resident European populations. Since 1994, a small dolphin watching industry has been operating in the estuary, with plans for expansion. The objectives of this were to a) assess the degree of residency of bottlenose dolphins in the Shannon; b) estimate the population size and assess the production of calves; c) examine the social structure of the population; d) study habitat use and e) examine the effects of boats on dolphin behaviour. Boat-based surveys and photo-identification techniques were used to derive a population estimate and to examine distribution and movements of individually identifiable dolphins over a two-year period. Land-based scan samples were used to examine behavioural activity and interactions of dolphins with all categories of boat traffic. Trips on dolphin watching boats examined whether these boats were interacting with the same individual dolphins on a trip, daily or weekly basis. Dolphins were recorded in all months of the year but with a seasonal peak between May and September. Many of the identifiable dolphins were resighted throughout the study indicating a high degree of residency. Using photo-identification and mark-recapture analyses, the population estimate for the Shannon is 113 dolphins (CV 0.14, 95% C.I. 94 - 161). The presence of neonatal calves only from July – September indicates that there is a marked breeding season for this population and that the area is important as a nursery area. Group sizes ranged from singletons to groups of 32 animals and while dolphins were seen throughout the study area, groups were frequently encountered in the narrow water at Kilcredaun and in the mouth of the estuary. A second area of concentrated sightings was identified further up-river around Moneypoint and Tarbert/Killimer. This group comprised a smaller number of individuals, and the re-encounter rate of these individuals in the same area suggests a degree of habitat partitioning. These dolphins may be more vulnerable to dolphin watching activities than the more diffuse numbers in the outer estuary. The influence of tidal cycle was recorded at Kilcredaun and at Killimer/Tarbert with a distinct peak in sightings in the four-hour period before low tide. The frequency distribution of association indices shows that there are few "strong" associations between individuals and supports the notion of a fluid and gregarious social structure. Dolphin watching boats were involved in 61.8% of all interactions with dolphin groups, higher than any other category of boat. At present, two operators make approximately 200 dolphin watching trips annually, carrying a total of 2,400 passengers per year. The operators are highly successful in locating dolphins (97%) and the tour boats rarely come into contact with each other on the water and generally search in different areas and watch different groups. The potential for land-based dolphin watching was examined and possible sites identified. The information from this study provides a basis from which sound conservation management strategies can be developed, in order to properly conserve the species and its habitat, to develop a sustainable dolphin watching industry and to develop/monitor other coastal zone industries such as oil and gas exploration and shipping development within the Shannon.