• The escallop Pecten maximus in Mulroy Bay

      Minchin, D. (Department of Fisheries and Forestry, 1981)
      Following the discovery in 1978 of large numbers of escallops in the North Water of Mulroy Bay, a detailed study of stocks was made in 1979. Spat settled out at shell height 190 to 220 µm from late July to 9 August, greatest density was 1,390 spat per metre of 12 mm diameter blue polypropylene rope. Mean daily growth rates from August to mid October ranged from 196.6 µm failing to 17.5 µm from mid October to December. Greatest densities of adult escallops occurred near rocks at depths from 3 to 15 m. Age frequency determinations showed that settlement had occurred every year since 1967. Serious predation by Asterias rubens took place on escallop held in lantern nets. The most successful containers for growth were North West plastic trays held below 5 m depth.
    • The Wexford commercial sea bass Dicentrarchus labrax (L.) fishery

      Fahy, E. (Department of Fisheries and Forestry, 1981)
      The Wexford sea bass fishery is operated during most months of the year with a high season from May to October. The fishery commenced in the 1950s but has shown a decline from the first years in which statistics became available. A proportion of the commercial catch comes from stake and ring nets with a mesh size of 18.4 cm in the round. Both take fish of similar fork length. Bass of 30-43 cm were the majority of those retained and they were mainly immatures. The smallest mature female examined in 1978 was a 6+ of 36.5 cm fork length. The greater part of the commercial catch is taken by line. Some details of the biology of bass in south east Ireland in 1978 are given: the fish fed mainly on shore crabs, sand shrimps and bait fishes. Sex ratios were approximately two females to each male. Growth in the mid 1970s differed little from other decades and it is concluded that bass in Irish waters conform to a single growth curve which is temporarily altered by good or bad growing years.
    • The Beltra Fishery, Co. Mayo and its sea-trout Salmo trutta stocks

      Fahy, E. (Department of Fisheries and Forestry, 1981)
      The sea trout stocks of the Lough Beltra catchment in Co. Mayo are described from a sample of 620 specimens collected in 1973 and 1974. These angler-caught fish displayed a low diversity in age categories and the samples contained few previous spawners. Variation in the success of parr growth in different years, between males and females and between A and B type smolts is compared. The incidence of A type growth is high, resembling that of a neighbouring catchment and the amount of B type growth can be related to length of the estuary. The Beltra angling fishery for sea trout exploits mainly two year smolt post-smolt. Traditionally the angling clientele have originated largely out of state and the decline in catches in recent years is attributed to a smaller volume of tourism in the post-1969 period. Catch per effort does not correlate with the supposed availability of sea trout and angling effort is regarded as the main factor deciding the yield from the fishery.
    • Sea-trout and their fisheries from the Dublin Fishery District

      Fahy, E. (Department of Fisheries and Forestry, 1981)
      Age, length and weight data from 440 sea-run trout are described together with data from 339 parr from a small trout stream. Pre-migratory length at age was not influenced by calcium content of nursery streams. Relatively faster growth of certain year classes in particular years was observed. Mean smolt age (2.1 years) was low. Sea run fish averaged at 0.86 sea-winters, contrasting with longer lived sea-trout on the Welsh coast but early maturation was observed in both. The regression coefficient for percentage previous spawners on mean individual weight in the Irish/Celtic Seas was lower than for fish from the Atlantic. The four principal fishing centres are each supplied with sea-trout by two to four small to medium sized rivers. A proportion of the catch is likely to originate in non licensed mullet gear. The annual catch declined from a peak of four tonnes in the 1950s to stabilise at 1.5 tonnes since the 1960s. The decline coincided with an increase in the ratio of draft to drift nets.
    • Spawning trout Salmo trutta L. populations in the Cummeragh System, Co. Kerry

      Fahy, E. (Department of Fisheries and Forestry, 1982)
      Concentrations totalling more than 300 spawning trout from five sites at three parts of the Cummeragh system were examined in 1980. The majority of the fish were sea trout but some brown trout and precocious males occurred at every site. Of the various physical characteristics of the sites, numbers of fish displayed the most consistent relationship with the volume of water in the pools where they occurred. Trout ranged from 22cm to 68cm fork length and maiden fish of two sea summers comprised the majority. Brown trout matured at a smaller size and younger age than sea trout. Males matured before females and older smolts before younger. Females outnumbered males in the entire collections although there were differences in this and other characteristics of the fish from one site to another, a result it is thought of the timing of sampling. The majority of male sea trout had a brown livery and more female than male trout displayed scars on the body behind the dorsal fin.
    • Spawning Trout in Eastern Connemara

      Fahy, E.; Nixon, J. J. (Department of Fisheries and Forestry, 1982)
      Concentrations totalling 299 trout from nine spawning sites in eastern Connemara in 1981 were examined to elucidate the spawning biology of these stocks. Sea trout made up the majority. Brown liveried fish predominated among migratory males (75%) but were few among females (2.5%). Males were of younger sea and river age than females and the ratio of females to males was lowest among the younger age categories. Scars and marks were evenly distributed between the sexes and 51% of females showed signs of being spent. Spawning Connemara sea trout were similar to spawning Cummeragh, Co. Kerry, sea trout in a number of, respects as for example their length at age but the spawning behaviour of fish in the two places differed considerably: the density of spawning fish was greater in the Cummeragh than in Connemara where immature trout occurred in the vicinity of the redds. The ratio of females to males was lower in Connemara than in the Cummeragh and males appeared to be more heavily marked in Connemara. The relevance of these observations to some known genetic characteristics of the stocks is briefly discussed.
    • A population study of the eel Anguilla anguilla in Meelick Bay, Lough Derg

      Moriarty, C. (Department of Fisheries and Forestry, 1983)
      Monthly samples totalling 1,945 yellow eels were caught by fyke net in a small bay, area 100 hectares, of a large lake in 1981 and 1982. Catch per unit effort figures showed that population density varied between months and between specific areas of the bay. Most of the eels sampled (80%) measured between 34 cm and 54 cm. Ages of a sample of 168 specimens taken in 1979 ranged from 7 to 17 years, 80% from 8 to 13 years. Length frequencies were constant throughout the bay within months but showed changes between months. Recapture rate of 1,660 eels tagged was extremely low at 1.14%. The results showed that (1) when eel population density is being compared between years, it is necessary to define exactly the positions where sampling takes place and (2) the eel population in this bay was not resident but appeared to be undergoing constant change throughout the warm months of the year.
    • Salmonid carrying capacity of streams in the Connemara region, a resource appraisal

      Fahy, E.; Nixon, J. J.; Murphy, M.; Dempster, S. (Department of Fisheries and Forestry, 1984)
      Standing crops of salmonids in the Connemara region are described from 80 site fishings made between March 1982 and May of the following year. Trout were more widely distributed than salmon, being able to exploit isolated water bodies as resident populations. High salmonid densities were associated with salmon which during the dry summer months were caught in large numbers on riffles. The smallest streams in the region supported only trout presumably because there was insufficient depth of water to permit the entry of salmon. Trout biomass and density within the region were distributed within the lower range reported from a number of countries in which brown trout are endemic and naturalised. Low saimonid densities at 16% of sites were in some cases associated with the rooting of angiosperms, and possibly oligotrophic conditions resulting from geological structure. Length at age of salmon and trout was similar to measurements recorded in Britain. The streams were important only for the first year of the trout life cycle. Because trout move downstream as they grow, occupying lakes during the later parr phase, and the entire streambed area in Connemara is one fortieth of the lake area, space is unlikely to be a critical constraint on the later parr phase. The condition of the stream substratum may be a factor in the production of sea trout; where loose gravels do not occur in shallow nursery streams, the catchments tend towards producing "brown" or "resident" rather than sea trout.
    • Sea trout and their exploitation by draft net from the Feale and Munster Blackwater Rivers, southern Ireland

      Fahy, E. (Department of Fisheries and Forestry, 1984)
      Biological characteristics of sea trout exploited in the rivers Bride (Co. Waterford) by angling and Feale (Co. Kerry) by draft net are described from small collections of scales and life data. Both stocks are short lived, poorly conditioned and have smolts whose fork lengths range between 19 and 26cm. Draft net fishing for these trout is conducted with relatively large meshed nets (4.45cm knot to knot). In the Feale highest catches are made in June and July and fish aged two sea summers constitute the majority of captures. A draft net mesh size smaller than the ordinary statutory minimum is required to retain large numbers of post-smoIt. A bunt mesh of 2.5cm knot to knot is effective in doing so.
    • Chemical contaminants in Irish estuarine and coastal waters, 1978 to 1988

      O'Sullivan, M. P.; Nixon, E. R.; McLaughlin, D.; O'Sullivan, M. L.; O'Sullivan, D. (Department of the Marine, 1991)
      Observations on the concentrations of heavy metals (mercury, cadmium, copper, lead and zinc) and chlorinated hydrocarbons (PCBs and the pesticides, lindane, dieldrin, DDTs and chlordanes) are presented. Sources comprise mussels and oysters from twenty six estuarine and coastal locations and in fin fish landed from all coasts. Data on heavy metals and nutrients in sea water and heavy metals in sediments for nine estuaries are also reported. Data were collected to comply with the Joint Monitoring Programme of the Oslo and Paris Commissions and with the Cooperative Monitoring Programme of the International Council for the Exploration of the Sea. The locations sampled included Boyne estuary, Dublin Bay, Wexford Harbour, Barrow estuary, Waterford Harbour, Cork Harbour, Bandon estuary, Tralee Bay, Shannon estuary, Clarinbridge, Kilkieran Bay, Clew Bay, Killary Harbour and Mulroy Bay. Four cases of elevated concentrations of cadmium, two each of copper, zinc and mercury and one of lead are reported. The general overall temporal trend in metal levels has been of stability or, in the case of more marked contamination, of reduction. The degree of organochlorine contamination was low in all the estuaries and shellfish growing areas monitored. No instances of contamination exceeding tolerance levels in shellfish and fin fish for human consumption were recorded. With very few exceptions, it was found that Irish coastal waters enjoyed exceptionally low levels of contamination.
    • The western spurdog Squalus acanthias L. fishery in 1989 and 1990, with observations on the further development of the gillnet fishery directed on the species

      Fahy, E. (Department of the Marine, 1992)
      Between 1987 and 1990 the western fisheries of spurdog briefly harvested heavy then progressively reduced landings. These were sampled in each year. The peak and post-peak fisheries have been described and this account is of the fishery in 1989 and 1990. Although the catch per effort has declined substantially from the peak fishery, spurdog remains an important target species. The fishery is assessed from 856 individuals captured in 1989 and 688 the following year. The following criteria of sampled fish classified according to method of capture were examined: sex ratio, weight, age and a growth index. Gillnet-caught females are regarded as indicators of the broodstock which shows signs of having made some recovery from its immediate post peak condition. The Carrigaholt gill net fishery, the index fishery which has been monitored for four years, exploits a range of species by gill net, spurdog and gadoids being the principal ones to date, and it has increased its fishing capacity over the period. In 1989 and 1990 effort was directed on hake; some characteristics of these landings are given and compared with gill net caught hake from other parts of the country.
    • A second assessment of the stock of megrim Lepiodorhombus whiffiagonis in Divisions Vll b, c, j and k

      Fahy, E.; Gleeson, P. (Department of the Marine, 1992)
      An assessment of megrim captured by Irish and joint venture (Spanish) vessels in Divisions Vll b, c, j, k is based on landings from both fleets and discards from Irish vessels targeting whitefish and Nephrops. Fishing activity by the joint venture fleet is centred on the 200m depth contour. Megrim CPUE has declined since 1985. Lepidorhombus whiffiagonis constitutes the majority of the landings by joint venture vessels; L. boscii amounts up to 2% by weight of the landings from deeper waters. In catches of undersized megrim, L. boscii was 12% of the total. Landings of L. whiffiagonis have similar length frequency distributions in the Irish inshore and joint venture fleets. There are indications of what may be seasonal abundance in the discards and landings of Irish vessels fishing inshore. Discards were calculated as 77% of landed weight in the first half of the year and 31% in the second. Megrim with an inshore provenance were slightly larger than those coming from deeper waters. The following growth parameters were calculated: L∞ = 51.2cm, k = 0.17 and to = -0.97. A catch curve derived from the combined landed and discarded megrim has a value of Z = 0.45, slightly less than the value calculated for the inshore Irish fleet (0.49). F is consequently in much the same position as in the 1989-90 assessment, on the negative slope of the yield per recruit curve.
    • Aspects of the exploitation of hake Merluccius merluccius belonging to the northern stock by fleets based in Ireland

      Fahy, E.; Gleeson, P. (Department of the Marine, 1993)
      The development of the hake fishery in the ICES Divisions adjoining Ireland displays strong similarities to the fishery for megrim; Ireland's landings of hake rose from 100t per year in 1979 to 2,000t ten years later. Most hake comes from Divisions Vllg-k. The Communities Logbook of the Irish-Spanish joint venture fleet provides a short time series. CPUE by both demersal trawl and long line declined sharply between 1985 and 1991. The second quarter is the most productive of hake landings but otherwise there is no clear seasonal pattern. Hake were sampled on a half yearly basis and the fish were aged on the otoliths with a success rate of 70%. Ages in the first half were adjusted to a birth date of 1 January. Mean lengths at age were higher than those calculated by statistical methods (Normsep.). Length frequencies indicated two age groups in the discards. Methods of capturing hake have altered over the past five years, gill nets have increased their share of the Irish catch and, in 1991, were a close second to demersal trawl. Age of recruitment to the landings is 2-4 years. Discard hake was calculated at 25-163% by weight of landings per quarter in 1991, higher values coming from small-meshed nets targeting Nephrops. Survivorship curves based on aged length frequencies of hake taken by whitefish boats provided F values of between 0.40 and 0.76. These results are high and together with sharply declining CPUE would seem to suggest the part of the stock in Divisions Vllb-c and Vllg-k is more heavily fished than the stock in other parts of Sub-area VII.
    • The European eel fishery in 1993 and 1994

      Moriarty, C. (Marine Institute, 1996)
      A group of 17 experts, representing 9 member states of the EU, undertook in March 1995 the Concerted Action AIR A94-1939 entitled Enhancement of the European eel fishery and conservation of the species. This paper presents the results of the first phase of the study which aimed to compile a database of information on the eel in the 9 states. The total annual yield of European eel was estimated to lie between 20,000 t and 30,000 t. Glass eels account for 4% of the total by weight and 33% by value. The value of the catch as paid to the fisherman was estimated at 180 M ECU and with value added as 375 M ECU. Manpower engaged fulltime in eel fishing was relatively low, fewer than 500 individuals. Numbers engaged part-time totalled at least 25,000. Although rarely providing the mainstay of a fishing community, the eel made a sociological contribution out of all proportion to its cash value. Yields greater than 5 kg per hectare were attained in a variety of habitats throughout the region. The highest yields per hectare recorded were 324 kg in one Italian coastal lagoon, 75 kg in another, 52 kg in a French Mediterranean lagoon and 40 kg in a Norwegian river and lake system. The yield from most fisheries was less than 5 kg per ha. This implied that proper management could greatly increase yields throughout the geographical range of the species. Between 2 and 3 billion young eels were captured annually, of which more than 95% were killed for consumption at that young stage, while less than 5% were harvested at later stages or left to contribute to the breeding stock. The implication was that adequate glass eels existed for a greatly enhanced stocking programme. Many eel fisheries had declined in the course of the previous twenty years, the principal factors appearing to be recruitment failure and inadequate management measures. Eel fishing can be undertaken with a low capital investment and provides important opportunities for work in communities where unemployment is high.
    • Management of the European Eel

      Moriarty, C. (ed); Dekker, W. (ed) (Marine Institute, 1997)
      Concern expressed by fishermen, fish culturists and scientists alike on the decline in recruitment and fishery yields of the eel led to the establishment of a working group, EC Concerted Action AIR A94-1939, to pursue a project entitled Enhancement of the European eel fishery and conservation of the species. Scientists from ten countries have contributed to the current report and its predecessor, published in 1996. The reports present an account of the eel fishery together with scientific data of significance in control of the stocks and make recommendations for future management.
    • Catch analysis of shrimp Palaemon serratus (Pennant) taken by different mesh sizes

      Fahy, E.; Forrestt, N.; Oakley, L. (Marine Institute, 1998)
      Five mesh sizes were used to sample shrimp Palaemon serratus at depths of less than 30 m in Bantry Bay, southwest Ireland from June 1996 to March 1997. All of the meshes, with the exception of the smallest (2.5 mm) were made up of polyethylene and they were distributed over a gang of 20 Chinesehat-ended creels which were fished on fourteen occasions throughout the period which overlapped with the commercial fishing season. Some 5,000 shrimp were captured and the size distribution of the total catch per month reflected the growth of the species so it is supposed that the population was representatively sampled throughout. Selection was calculated using the alternate hauls method. Shrimps did not enter the pots in any numbers below the length of 50 mm (total length) and mesh selection could not he demonstrated at a mesh size of 5.2 mm. Thereafter, as the mesh sizes were ascended, selectivity became more significant. It was however weak; Lc values ranged between 58-75 mm for females and 71-88 mm total lengths for males for mesh sizes of 7.5 - 13.5 mm. These lengths coincide with the centre of the length frequency distribution of shrimp. As the mesh size increased, the ratio of females to males rose, but the numbers per haul declined abruptly in the 13.5 mm mesh.
    • Strategy for the development of the eel fishery in Ireland

      Moriarty, C. (Marine Institute, 1999)
      In the course of a reply to a Parliamentary Question on eel in February 1997, the Minister stated that ‘there is considerable potential for development of the fishery and an integrated development strategy plan is being formulated’. The Marine Institute and other bodies were asked by the Department of the Marine to prepare a submission. The material which follows is based on the author’s work as a biologist, first in the fisheries service of the Government and, subsequently in the Marine Institute.
    • Development of the Irish Eel Fishery: Proceedings of a National Workshop - Dun Laoghaire, 7 July 1998

      Watson, L. (ed); Moriarty, C. (ed); Gargan, P. (ed) (Marine Institute, 1999)
      Increasing awareness of the value of eel fishing led to a decision by the Minister for the Marine to formulate a national eel strategy. As a contribution to the necessary gathering of views and information, the principal authorities concerned convened an Eel Management Workshop on 7th July 1998 at the Royal Marine Hotel in Dun Laoghaire. The Workshop was co-hosted by an Bord Iascaigh Mhara (BIM), the Marine Institute (MI) and the Central Fisheries Board (CFB), and was attended by 100 participants representing all sectors, including the eel fisheries and co-operatives, eel farmers, eel processors and smokers, the regional fisheries hoards and the state development and regulatory agencies from both sides of the border. It was decided to hold a workshop on eel to heighten awareness of this most intriguing and valuable resource in Ireland, and to establish the baseline data for a national strategy for the development of the Irish eel fishery to be announced by the Minister for the Marine and Natural Resources during 1998.
    • A Benthic Survey of Inner Bantry Bay

      Neiland, S.; McMahon, T. (Marine Institute, 1999)
      In February 1993 sediment samples were collected from a total of 18 stations in Bantry Harbour, Glengarriff Harbour and along the north shore of Whiddy Island. The samples were analysed for grain size, organic carbon content and the abundance of benthic infauna. The benthic infauna were identified to family level. The sediments in Bantry Harbour and Glengarriff Harbour were comprised of fine particles with typically >80% of the dry weight being in the silt/clay (<63 μm) fraction. In contrast, the sediments close to Whiddy Island contained relatively high amounts of coarser material. In Bantry Harbour a total of 53 families with 742 individuals were identified from the ten stations sampled. Of the 53 families identified, 21 were Polychaeta, 6 Bivalvia, 7 Gastropoda, 3 Echinodermata, and 16 Crustacea. A total of 31 families with 491 individuals were identified from the five stations sampled in the Glengarriff Harbour area. Of these 16 were Polychaeta, 4 were Bivalvia, 3 were Gastropoda, 1 was Echinodermata, and 7 were Crustacea. From the three stations sampled in the vicinity of Whiddy Island 47 families with 461 individuals were identified. Of these 23 were Polychaeta, 8 Bivalvia, 4 Gastropoda, 2 Echinodermata, and 10 Crustacea. In Bantry Harbour and Glengarriff Harbour cirratulid polychaetes were dominant and the benthic infaunal composition was indicative of stressed environmental conditions. In contrast, the sediments close to Whiddy Island exhibited a very healthy faunal composition with no one family predominating and high numbers of amphiuroid echinoderms were recorded from these sampling stations.
    • 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.