Now showing items 1-20 of 47

    • Pelagic Eggs and Young Stages of Fishes Taken on the South Coast of Ireland in 1967

      Kennedy, M; Fitzmaurice, P (Department of Agriculture and Fisheries (Fisheries Division), 1969)
      Emes W. L. Halt was one of the pioneers of research on the spawning and early development of marine fishes, and collections of pelagic eggs and young stages of fishes made by him on the west coast of Ireland were the basis of some major contributions to the then young science of fisheries biology (HoIt 1891, 1893, 1899). Much more recently Fives (1967a) has worked on pelagic young stages of fishes taken in the plankton on the coasts of Galway and Clare. Collections of eggs and young stages of clupeoids have been made on, the south coast of Ireland in winter during the years 1960-1962 (Bud and Bracken, 1965; Bracken and Kennedy, 1967). Hitherto, however, no collections of eggs or young stages of other fishes appear to have been made on the south coast. As part of a programme of research by the Inland Fisheries Trust into the biology of the bass, Dicerntrarchus labrax (L.) in Irish waters, tow-netting for bass eggs was carried out at four centres on the southeast and south coasts of Ireland during the period April to June 1967. Pelagic eggs of a variety of species of fish, including bass, were obtained, as well as larvae, post-larvae and fry. The tow-netting was done close to shore and in estuaries-areas not as a rule sampled as extensively as the offshore waters where the major commercial fishes The results of the tow-nettings help, therefore, to fill in some of the gaps in existing data on the reproduction of fishes on the Irish coast.
    • Irish Investigation on the Lobster (Homarus vulgaris Edw.)

      Gibson, F A (Department of Agriculture and Fisheries (Fisheries Division), 1967)
      Commercially the lobster (Homarua vulgaris Edw.) is the most important shellfish in Ireland. The Irish coast is deeply indented, except on the east, and is well suited for the exploitation of lobsters. Even on the east coast amidst a predominantly sandy shoreline, a number of discreet areas are fished actively.
    • The feeding relationships of a small demersal fish community in the western Irish Sea

      O'Brien, K; Fives, J M (Department of the Marine, 1994)
      The feeding relationships of seasonal and resident fishes captured on a sandy substratum in the lrish Sea, in June and in September, were investigated. Stomach content analysis of the 17 species examined indicated four main feeding tvpes in the June sample and three in the September sample. The majority of the species analysed in both June and September showed the same food preferences in both months. Most of the fish species showed some changes in diet with increasing length (ontogenetic shift) - some became more specialized and others favoured more varied diet. There was no evidence of competition between specialist feeders within size groups.
    • The Distribution of Mytilus edulis and Anomid Larvae in Kilkieran Bay, Co. Galway

      Wilson, J H (Department of the Marine, 1987)
      The temporal and spatial distribution of Mytiius edulis and Anomiidae larvae were recorded in Kilkieran Bay, Co. Galway, during 1984 and 1985. Only larvae close to settlement (M. edulis larvae > 250 µm length and Anomiid larvae > 160 µm length) were considered. M. edulis larvae were commonest in late July, mid-August and early September 1984 and in early May, mid-June and early September 1985, while Anomiid larvae were commonest in late June and rnid-July 1984 and mid-June and early September 1985. M. edulis larvae were generally found in higher densities at the mouth of the bay, while Anomiids were more evenly dispersed, with high concentrations over the oyster beds. There was no significant (P < 0.05) net import of either species of larvae into the bay over tidal cycles.
    • Temporal and Spatial Distribution of Ostrea edulis Larvae in Kilkieran Bay, Co. Galway

      Wilson, J H (Department of the Marine, 1987)
      Concentrations and size distributions of Ostrea edulis L larvae were recorded in Kilkieran Bay, Co. Galway, Ireland, during 1984 and 1985. Larvae were most abundant during July and August in both years. Large larvae ≥ 250 µm were homogeneously distributed through the vertical water column. Higher percentages of smaller larvae ≤ 250 µm were recorded at stations near the mouth of the bay than at stations on or near the beds. Variations in tidal amplitude and low salinities caused displacement of larvae from the beds. There were no significant losses of larvae from the inner bay.
    • A Review of the Dunmore East Herring Fishery (1962-1968)

      Molloy, J (Department of Agriculture and Fisheries (Fisheries Division), 1969)
      The winter herring fishery off the south coast of Ireland, based on what is commonly called the Dunmore stock, has been studied in detail by earlier workers and particularly by Bracken and Burd (1965). In their paper, they reviewed the fishery up to 1963 and arrived at conclusions regarding the economic yield of the fishery. They stated that, “ with the major spawning grounds (where the intense fishery takes place) situated within Irish exclusive fishery limits, there is considerable scope for the control of effort in such a way that, for the first time, a herring stock might be rationally exploited”. Since 1963, certain changes have taken place in respect of the stocks themselves and the fishing to which they are subjected. The purpose of this paper is to bring these changes to light and to compare the state of the fishery during the seasons 1962/63 to 1967/68 with that during the period of Braken’s and Burd’s observations.
    • Age, Growth and Maturity of Irish lobsters

      Gibson, F A (Department of Agriculture and Fisheries (Fisheries Division), 1969)
      A completely satisfactory method of ageing lobstem has not been developed. Gibson (1967) attempted to age lobsters using the principles of the von Bertalanffy equation as suggested by Beverton and Holt (1957). In this case the only determinable parameters were L∞, K and the annual growth rate was calculated from the recapture of tagged lobsters which had been at liberty for a period of one year, during which time they had or had not moulted. The smooth curve produced from these data suggested that lobsters first come into the catch, in large numbers at the end of their fifth year and are fully recruited in the sixth year. In reaching this age, the rate at which lobsters grow does not appear to be consistent, and does not appear to be so throughout the life span.
    • Stocks of Nephrops norvegicus off the south coast of Ireland

      Gibson, F A (Department of Agriculture and Fisheries (Fisheries Division), 1967)
      Nephrops norvegicus is also known popularly as the Dublin Bay Prawn or Norway Lobster. The stocks of prawns in depths down to 60 fathoms (109m) have been studies since 1956, off the south of Ireland, from Mine Head, Co. Waterford, to the Kenmare River, Co. Kerry. The present paper is concerned with data obtained from the research vessel Cú Feasa, together with other samples collected from commercial fishing boats, during the years 1963 to 1966 inclusive.
    • Occurance of Eggs of Echiodon drummondi Thompson on the Coast of County Kerry

      Kennedy, M; Champ, T (Department of Agriculture and Fisheries (Fisheries Division), 1971)
      As part of a programme of research on the spawning of bass Dicentrarchus labrax (L), tow-netting for pelagic fish eggs has ben carried out on various parts of the Irish coast during the years 1967 to 1971 inclusive. In May, 1970, in the course of tow-netting in Blasket Sound, Co. Kerry, eggs of the pearlfish Echiodon drummondi Thompson were taken in three hauls. Most of the eggs were hatched out and the larvae reared for some days. This appears to be the first record of the eggs of this species on the Irish coast. The following discusses the natural history of pearlfishes and the hauls in which pearlfish eggs were obtained.
    • The Whiting Fishery Off Counties Dublin and Louth On the East Coast of Ireland: Research Vessel Investigations

      Hillis, J P (Department of Agriculture and Fisheries (Fisheries Division), 1971)
      The stock of whiting (Merlangius merlangus L.) off Counties Dublin and Louth forms the basis of a commercial fishery (Hillis, 1968). This paper presents the result of research vessel investigations into the stock from July, 1962 to May, 1967. Hillis (1962, 1963) recorded the results from the early part of the period, which are also incorporated in the present work.
    • Reproductive cycle of the velvet swimming crab Necora puber (L.) (Decapoda, Brachyura, Portunidae) on the east coast of Ireland

      Bakir, W M A; Healy, B (Department of the Marine, 1995)
      An unfished population of Necora puber, in a coastal area just south of Dublin, was sampled monthly between August 1986 and November 1987 using baited creels. The reproductive cycle was analysed using gonad stages, the incidence and size distribution of ovigerous females and developmental stages of the egg masses. Both sexes started to breed at a carapace width of about 50 mm when they were about one year old. Seven ovarian and six testicular stages were recognised, both macro- and microscopically. The ovary underwent continuous cyclical changes and there was no distinct winter resting period. All ovigerous females had developing or ripe ovaries and they may thus produce more than one brood in a season. The main breeding season started in February with the greatest number of ovigerous females found in March-June and a peak in May. Less than 10% of females were ovigerous from August to January. The main periods of larval release were April, June and August. Spawning and recovering males were present throughout the year. Differences between the observed reproductive cycle and those studied in Britain and Spain are discussed.
    • Appraisal of the whelk Buccinum undatum fishery of the Southern Irish Sea with proposals for a management strategy

      Fahy, E; Yalloway, G; Gleeson, P (Department of the Marine, 1995)
      A small occasional fishery for whelk in the southern Irish Sea expanded in the early 1990s, particularly in 1993, to provide meat for the Far East. Between 1990 and 1993 the weight of whelk delivered by a fisherman to factory per day remained stable but the fishing effort increased by 44%. The quality of landings declined, increasing proportions of smaller whelk being retained. The most heavily fished populations apparently display a Lee effect. An age at length key was prepared from 3,081 individuals and is used to transform length to age frequencies within the area of interest. The weight compositions of graded samples, abstracted from processors' financial accounts, were converted to population numbers. The age of full recruitment is reckoned to be five years over the area of interest although it may fall to four in the most intensely fished whelk patches. A Thompson-Bell yield per recruit curve has Fmax at F=0.3. Only one fishery, at the northern fringes of the fishing area, has an F value (read from the catch curve) of less than this. F values of fisheries at the centre and south of the exploited area are all situated on the negative slope of the yield per recruit curve. Male maturation occurs at a length of 70 - 80 mm in the least and 50 mm in the most exploited populations. Thus, a measure to protect broodstock would require a size limit of approximately 70 - 80 mm which would, coincidentally, approximate the size for maximum sustainable yield. It would also have a catastrophic effect on the existing fisheries. A size limit of 50 mm is already in force.
    • Proceedings of the Third Annual Conference of the European Association of Fisheries Economists, Dublin, Ireland, 10-12 April 1991

      Hillis, J P (ed) (Department of the Marine, 1994)
      The European Association of Fisheries Economists (EAFE) was founded following a meeting of interested European fisheries economists at Esbjerg in August 1988. Its first Annual Conference was a modest one held at Brussels in January 1990, while the second was held at Lisbon in March 1990. At Lisbon, the Bureau accepted an invitation to meet in Dublin in the spring of 1991, so the Third Annual Conference of EAFE was duly held in Dublin, at the Headquarters of the Geological Survey of Ireland, during the 10th to 12th April, 1991. Three themes were selected for the Conference, (1) The Single European Market, (2) Capacity, and (3) Coastal Management. In the event, the second theme attracted the most interest, reflecting the widespread preoccupation with overfishing and the problems inherent in trying to rectify it; papers accepted included two in Section 1, thirteen in Section 2 and five in Section 3, although one (No. 16), originally submitted in Section 3, was by reason of the nature of its contents finally transferred to Section 2.
    • The exploitation of angler fish Lophius Spp. in Irish waters

      Fahy, E; Gleeson, P (Department of the Marine, 1992)
      Two species of European angler, Lophius plscatorius and L. budegassa occur In Irish waters. L piscatorius is dominant, particularly closer to the coast; L. budegassa becomes more important moving south and in landings from medium/deep water. Three stocks of anglers are recognized; this work concerns the fish in the central one, specifically in ICES Divisions Vllb, c and j,k. Anglers are taken in a mixed demersal fishery, and they are particularly associated with hake and megrim. Most landings of the species come from ICES Divisions VlIg-k. The species have traditionally been taken in a mixed demersal fishery, mainly by France and Scotland. Ireland's landings have increased from 100t in 1977 to in excess of 2,000t in recent years. Species composition of the landings was determined by port sampling. The proportion of Lophius piscatorius, while still dominant, has declined since the mid 1980s. A short CPUE time series from joint venture vessels fishing medium/deep water (approximately 200 m) shows no consistent trends although the values for 1991 were the lowest in the six years. Irish vessels take anglers of slightly greater weight than do their joint venture (Spanish) counterparts. Length frequency distributions of both species from the Irish trawl fishery are available from 1987 to 1991 inclusive. They are redistributed by age using French ALKs. The age distribution shows no particular trend for L. budegassa whereas that for L. piscatorius shows evidence of strong year classes from the mid 1980s passing through the population. The sharp reduction in angler CPUE in 1991 may have resulted from the exhaustion of strong mid 1980s year classes of L. piscatorius. A large plus group in the age distribution of L. piscatorius restricted interpretation of its population structure. Discarding of anglers appears to be very low in the south western Irish trawl fisheries, an estimate of 6.8% landed weight being used in this assessment. A catch curve for L. piscaforius suggested a value of Z+0.48; taking M=0.15 provides a value for F=0.33, to the right of Fmax and in general agreement with what has been concluded for this species in recent assessments.
    • Large scale Phaeocystis blooms off the west cost of Ireland in 1990

      Pybus, C; McGrath, D (Department of the Marine, 1992)
      The occurrence of blooms of Phaeocystis are reported from the West Coast of Ireland in the spring of 1990. Populations were observed along the coastlines of counties Clare, Galway, Mayo, Sligo and Donegal. The causative species is believed to have been P. globosa. These blooms represent the largest scale development of this or any other phytoplanktonic species recorded from this geographic area.
    • The south eastern ray Raja spp. fishery, with observations on the growth of rays in Irish waters and their commercial grading.

      Fahy, E (Department of the Marine, 1991)
      Five species contribute to the landings of the south eastern ray fishery, Raja microocellata being additional to the four more generally encountered in the Irish Sea. Fishing logs from 17 vessels were examined; they described more than 26,000 hours of fishing effort, most of it in division Vllg. Auction records contained a higher than expected proportion of small grades. The fishery is assessed as being more heavily exploited than the ray fisheries of division Vila. As far as possible, growth curves of rays in Irish waters were calculated on the fully recruited age groups. Values for L∞ were greater for females than males of all species; those for R. montagui and R. naevus are less than in other published accounts. Values of K range between 0.19 and 0.33 while values of to are between -3.009 and +0.49. In general, there is more variability in the values of to than is warranted by life cycles which are basically similar. Fishermen sort rays primarily on their size and secondarily on their external appearance, certain species having greater values than others. The supply of fish influences the outcome, insufficient quantities requiring that fish which would normally be segregated are bulked. Another Influence is the local occurrence of certain species. Statistical associations among species differ with grade, the smaller growing species rarely gaining access to the larger grades; when they do they are usually associated with species of lesser value. Rays are probably most effectively sampled by working on size grades within which samples are chosen at random.
    • The feeding relationships of the shanny, Lipophyrys pholis (L.) and Montagu's blenny, Coryphoblennius galerita (L.) (Teleostei:Blenniidae)

      O'Farrell, M M; Fives, J M (Department of the Marine, 1990)
      Collections of 279 specimens of Montagu's blenny, Coryphoblennius galerita (L.), and 276 shanny, Lipophrys pholis (L.), were made over a ten month period on a 2km stretch of the western shore of Mweenish Island on the west coast of Ireland. Further collections of 99 L. pholis and 8 C. galerita were made in March and April at two mainland sites. Sampling was confined to rockpools in the upper midshore region. The result of this bias was that while all age groups of C. galerita were collected, most of the L. pholis taken were less than two years old. Both species are omnivorous and exhibit definite seasonal feeding patterns. In general, C. galerita mutilate prey species, whereas only juvenile L. pholis are found to do this. Both species exploit a wide range of intertidal organisms. The ecological differentiation necessary for co-existence is evident, polychaetes are important only in the diet of juvenile C. galerita and bivalves and gastropods are important to L. pholis. There are only two food categories of importance to adult C. galerita and this may reflect the ecological stress on C. galerita of the habitat and the presence of L. pholis.
    • The post-peak-yield gill-net fishery for spurdog Squalus acanthias L. in Western Ireland

      Fahy, E; Gleeson, P (Department of the Marine, 1990)
      A gill net fishery, directed on Spurdog, expanded rapidly on the western coast of Ireland in the 1980s and quickly collapsed, the fishermen moving offshore in pursuit of smaller individuals. Catch per effort and landing data in the gill net fishery are used to estimate the size of the mature and maturing component of the south western "stock" which is within a range of 3,700 tonnes (landed) and 5,700 (calculated). An appraisal of the post-peak-yield landings reveals that the average individual weight declined from those of peak landings, in males by 9.5% and females 32.0%, and the percentage of females in them declined from 75 to 19%. The majority of the later catches were immatures whereas the peak-yield catches were mainly mature and maturing females. The average age of females was reduced from 19 to 16 years - 18 to 17 years in the case of males - and later captures were a shorter length at age. The fate of the depleted stock is not known and the possibility of its locus having moved elsewhere cannot be discounted.
    • Fisheries for Ray (Batoidei) in Western statistical area viia, investigated through the commercial catches.

      Fahy, E (Department of the Marine, 1989)
      The status of the Irish Sea ray fishery is investigated using commercial catches of rays landed into two ports, Howth and Arklow. Approximately 80 45kg boxes were examined monthly over a year when approximately 100 individuals of each of the four contributing species were aged and measured. The species are R. naevus, montagui, clavata and brachyura. These are inter-mixed and casually segregated into four grades on their length. Weighting factors are provided to raise the sampled numbers to total landings. The frequency distribution of grades at the two ports is established from an analysis of some 5,700 commercial transactions. At Arklow, the pattern is stable from one year to another and apparently seasonal. Arklow boats have a short range. The pattern of landings at Howth is more complex; these vessels have a longer range and probably exploit various ages of rays. Growth in all four species occurs most actively during the summer months, slowing down in the winter. Annulus formation is not readily associated with the conventional birth date of 1 January. Coefficients of total mortality (Z) are high for the four species (0.38-1.00), higher than those found in a recent study of rays in Carmarthen Bay. R. brachyura is the most valuable species. R. naevus is the most numerous, possibly because it has a competitive advantage due to its age at full recruitment being one year later than those of the other three species. The yield of rays increases moving offshore and in a southerly direction in the Irish Sea. Landings into Irish ports by Irish vessels have increased between 1903 and 1985 although, until recently, ray as a percentage of total demersal landings was declining, from the 1950s.
    • A Review and Catalogue of the Amphipoda (Crustacea) in Ireland

      Costello, M J; Holmes, J M C; McGrath, D; Myers, A A (Department of the Marine, 1989)
      The distribution and source of published and unpublished records of 307 marine, freshwater, terrestrial and subterranean amphipod species in Ireland are documented. A historical account of studies on amphipods in Ireland, including the researchers, frequency of publications, localities and habitats surveyed, and sampling methods, is presented. The occurrence of introduced species, commensalism, and parasitism is noted. The amphipod fauna recorded from Galway Bay, Kilkieran Bay, the Clare Island Survey, Belfast Lough, Strangford Lough, Dublin Bay, Carnsore Point, Cork Harbour, Kinsale Harbour, Lough Hyne and Valentia is discussed. The Irish and British lists are compared. Differences with the British list are largely explicable in terms of the latitudinal range of a species. The balance consists of rare, introduced, recently described, and unconfirmed records.