• The Early Life of Brown Trout (Salmo Trutta L.)

      Kennedy, M.; Fitzmaurice, P. (Department of Agriculture and Fisheries [Fisheries Division], 1968)
      The programme of research included field and laboratory studies of certain aspects of the early life history of the trout that are considered below.
    • Ecological Changes over 21 Years Caused by Drainage of a salmonid stream, the Trimblestown River

      O'Grady, M. F. (Department of Agriculture and Fisheries [Fisheries Division], 1991)
      A site on the Trimblestown River (Boyne Catchment) studied by McCarthy (1977 and 1983), pre- and post-drainage (1968 to 1974), was re-examined by the author in 1989. Changes in the nature of the stream bed, in-stream and bank flora and fish stocks over the entire period (1968 to 1989) are reviewed. Data indicate a general ecological recovery of the site 17 years after drainage works.
    • Ecological Changes over 30 Years caused by drainage of a salmonid stream, the Bunree River

      O'Grady, M. F.; King, J. J. (Department of Agriculture and Fisheries [Fisheries Division], 1992)
      The general ecology of two sites in the Bunree River, May catchment are described for 1990 and compared with the observations of Toner, O'Riordan and Twomey, (1965) at the same sites 30 years ago when parts of this catchment were subjected to arterial drainage. Differences observed are discussed with particular reference to salmonid populations.
    • The Ecology of Brown Trout and Juvenile Salmon in the River Owena, Co. Donegal

      McCarthy, D .T. (Department of Agriculture and Fisheries [Fisheries Division], 1972)
      The growth rate and population structure of brown trout and juvenile salmon in two oligotrophic nursery streams in County Donegal in the North west of Ireland are compared, as well as data on sex ratios and sexual maturity. Details of the food of brown trout and salmon and the smolt run in 1967 are discussed. Estimates of fish population density and biomass for these rivers have been made and related to estimates made in two other rivers of similar terrain, one oligotrophic and the other eutrophic. Pre-migratory mortality rates in the salmon populations are discussed.
    • The Effects of Drainage on the Trimblestown River

      McCarthy, D. T. (Department of Agriculture and Fisheries [Fisheries Division], 1977)
      The effects of arterial drainage on the macro-invertebrates and flora of a salmon nursery stream are described. A section of the Trimblestown River, Co. Meath was sampled from 1968 to 1974. In drainage operations of this kind the substratum where insect life predominates is removed, also fish and salmonid ova and fry life is affected by mechanical disturbance. A Surber stream-bottom sampler covering an area of 1 square ft (O.093m2) was used to take 107 samples. Wet and dry weights of the fauna were determined. A survey of the aquatic flora, pre- and post-drainage is also described. The fauna and flora were seriously depleted after drainage but recovered rapidly both in numbers and biomass a year after drainage was completed. There was an increase in the growth of emergent vegetation after drainage. Filamentous algae and Chara sp. recolonised the bed of the river replacing two submerged species (Fontinalis sp and Rorippa nasturtium) which had been abundant prior to drainage.
    • Feeding Relationships of trout salmo trutta L., Perch Perca fluviatilis L., and Roach Rutilus rutilus (L.) in Lough Sheelin, Ireland

      Gargan, P. G.; O'Grady, M. F. (Department of Agriculture and Fisheries [Fisheries Division], 1992)
      Samples of trout, perch and roach were collected by gill netting from eight sampling stations over the period February 1982 - March 1984 to assess competition for food between the three species. At each of the sampling stations quantitative collections of benthic invertebrates were taken in order to examine the relationship between feeding and food availibility. Results indicate a significant correlation in diet between trout and perch, little correlation in diet between trout and roach and moderate correlation between perch and roach. The most important competitive interaction between all three fish species is likely to be at their juvenile stage for a cladoceran diet.
    • Feeding relationships of trout Salmo trutta perch Perca fluviatilis L and roach Rutilus rutilus L in Lough Sheelin Ireland.

      Gargan, P. G.; O'Grady, M. F. (Marine Institute, 1992)
      Samples of trout, perch and roach were collected by gill netting from eight sampling stations over the period February 1982 - March 1984 to assess competition for food between the three species. At each of the sampling stations quantitative collections of benthic invertebrates were taken in order to examine the relationship between feeding and food availibility.
    • Feeding, Growth, and Parasites of Trout Salmo Trutta L. From Mulroy Bay, an Irish Sea Lough

      Fahy, E. (Department of Agriculture and Fisheries [Fisheries Division], 1985)
      The feeding and gut parasite burden of 354 trout collected between May 1980 and April 1981 from Mulroy Bay on the north coast of Ireland are described and compared with a collection of trout from the Irish Sea. The sea ages of the fish ranged between 0 and 2 sea winters, more than 90% being post-smalt. Males and females were equally represented in the younger, females predominated in the older. The food web was larger than in the Irish Sea, insects and crustaceans being its most numerous constituents but fish making up the greatest volume. Shoal fishes were relatively unimportant. Parasites comprised five species of Digenea, one cestode and a nematode. All occurred at a relatively low incidence and burden. Weights of the Mulroy fish were lower than for trout of equivalent length from the Irish Sea.
    • Fluctuations in the Characteristics in Irish Salmon

      Went, A. E .J.; Twomey, E. (Department of Agriculture and Fisheries [Fisheries Division], 1971)
      Fluctuations in the catches and stocks of fish are exceedingly important and have interested scientific workers for years. As far as the salmon is concerned it is known that great fluctuations occur not only in the number of fish entering the rivers from year to year but also in their character. This paper is an attempt to put on record certain changes, some of which have already been recorded in papers on Irish salmon published in a very wide range of journals.
    • Insect Emergence Data from Four Small Lakes in the South and Southwest of Ireland

      Bracken, J. J.; Murray, D A. (Department of Agriculture and Fisheries [Fisheries Division], 1973)
      Emerging insects from four small lakes in Counties Cork and Kerry were captured using floating Mundie emergence traps during the period from late April to early November 1969. The data obtained are examined to provide information on distribution, emergence periods and seasonal fluctuations in numbers of insects present. The traps were serviced at weekly intervals and the weekly maximum/minimum temperature fluctuation was observed. Chironomids were the dominant forms emerging during the period of investigation, 51 species were recorded but only five were present in significant numbers; 19 Trichopteran species were taken, but only four in significant numbers; one species each of Chaoboridae and Ephemeroptera was taken. There does not appear to be a direct correlation between high temperatures and peak emergence within the Chironomidae, however the peak emergence of Chaoborus flavicans in Lough Avaul coincides with the maximum temperature recorded (15 C). Differences in peak emergence periods of some similar species in different lakes are apparent.
    • An Investigation into the Chemical and Biological Effects of Pollution in the River Tolka

      O'Connor, M. A.; Bracken, J. J. (Department of Agriculture and Fisheries [Fisheries Division], 1980)
      Physico-chemical and biological sampling show that the River Tolka is affected by organic pollution over most of its length. Domestic sewage is the major contaminant. A distinct zonation of the river is noted as certain polluted areas are succeeded by downstream recovery zones. Many of the effluents and tributaries are investigated. Oxygen depletion and excessive ammonia concentrations are the factors most likely to have caused the observed faunal changes.
    • Irish Kelt Tagging Experiments

      Went, A. E. J. (Department of Agriculture and Fisheries [Fisheries Division], 1969)
      Since the beginning of the century large numbers of salmon kelts have been tagged in Irish waters and the results have been given in a series of papers...a considerable number of kelts have been tagged since 1962 at a number of stations in Ireland and they form the basis of this paper.
    • Irish Pike Investigations

      Kennedy, M. (Department of Agriculture and Fisheries [Fisheries Division], 1969)
      The spawning of pike was studied in 1965 and 1966 in five large Irish limestone lakes-Loughs Sheelin, Ennell, Mask, Corrib and Arrow. The spawning period was found to be February to April. Spawning took place in shallow, sheltered situations where there was a carpet of dead or living vegetation on the bottom at a depth of 20 to 60 cm. Spawning took place by day, at a water temperature of at least 9-1O C, when lake levels were high or rising. Gill-net catches reached a peak during periods of spawning. Weather conditions in February and March were much milder in 1966 than in 1965, and spawning began about a month earlier than in 1965. The eggs of Irish pike are 2.7 to 3.0 cm in diameter. They are golden to honey coloured, with a great many minute oil-globules distributed through the yolk in numerous tiny clusters. The incubation period in the field is probably 8-14 days, and the newly hatched larva is 8.0-9.0 mm long. For the first 10 days or so, the larvae hang vertically from the vegetation by means of adhesive glands on the head. They then become free-swimming, and soon afterwards begin to feed. At this stage they measure 13.0-13.5 mm. Their first food consists of small cladocera and copepods. Later, they feed on larger cladocera, amphipods, isopods, young stages of aquatic insects, and fish fry.
    • A List of Rotatoria Known to Occur in Ireland with Notes on Their Habitats and Distribution

      Horkan, J. P. K. (Department of Agriculture and Fisheries [Fisheries Division], 1981)
      A total of 315 species of rotifers are known to occur in Ireland. Of these 71 belong to the Bdelloidea and 244 to the Monogononta. Three species new to Ireland are now recorded and one of them is also a new record for the British Isles. A taxonomic list of the 315 species is given together with notes on ecology, where possible, and distribution. The names of recorders are included.
    • The Movement of Salmon (Salmo Salar) Through an Estuary and a Fish-Pass

      Jackson, P. A.; Howie, D. I. D. (Department of the Marine, 1967)
      In this paper we have attempted to analyze in quantitative terms the behaviour of the salmon of the River Erne during the important phase of migration when the fish first enter brackish and fresh water.
    • Observations on the Trichoptera of the Killarney Lakes, Co. Kerry, Ireland

      O'Connor, J .P.; Wise, E. J. (Department of Agriculture and Fisheries [Fisheries Division], 1984)
      Trichoptera were obtained in two separate surveys of the Killarney Lakes. During eutrophication investigations, larvae were collected at twelve littoral stations once a month for a year. As part of a special study of the Irish Trichoptera, larvae, pupae and imagines were collected extensively using both semiquantitative and qualitative techniques. The combined results of these two surveys demonstrated that the lakes possesed a rich and interesting trichopterous fauna. Altogether 71 species were recorded, representing half the known Irish Trichoptera. The Upper Lake had the poorest fauna with 29 species. By contrast, 54 and 58 species were recorded from Muckross Lake and Lough Leane respectively. A total of six species new to Ireland was discovered. Species of particular interest on the grounds of rarity or occurrence in lentic rather than lotic habitats included Apatania auricula (Forsslund), Athripsodes albifrons (Curtis) and Setades argentipunctellus McLachlan.
    • Papers Presented to the 7th Session of the EIFAC Working Party on Eel

      Moriarty, C. (ed) (Department of Agriculture and Fisheries [Fisheries Division], 1992)
      The Seventh Session of the Working Party on Eel of the European Inland Fisheries Advisory Commission was held in the Royal Hospital, Killmainham, Dublin. A list of the peer-reviewed papers and abstracts of other presentations to the session are given below. -- I M Domingos: Fluctuation of glass eel migration in the Mondego estuary (Portugal) in 1988 and 1989. -- Daniel Guerault, Raymonde Lecomte-Finiger, Yves Desaunay, Sylvie Biagianti-Risbourg, Pierre Beillois and Patrick Grellier: Glass eel arrivals in the Vilaine estuary (Northern Bay of Biscay) in 1990: Demographic features and early life history. -- Jan G P Klein Breteler: Effect of provenance and density on growth and survival of glass eels Anguilla anguilla (L.) in mesocosm experiments. -- R. Lecomte-Finiger, S. Biagianti-Risbourg, Y. Desaunay, D. Guerault, B. Fourcault, S. Planes and A. Yahyaoui: Age at recruitment of A. anguilla glass-eels on the eastern Atlantic coast as inferred from otolith growth increments. -- P McGovern and T K McCarthy: Elver migration in the River Corrib system, western Ireland. -- Christopher Moriarty: Catches of Anguilla anguilla (L.) elver on the Atlantic coast of Europe 1989-1990. -- Maria Assuncao Santos and Michael Weber: Growth studies on monthly captured glass eels from the Rio Minho in two recirculation systems. -- Raymonde Lecomte-Finiger: Age and birth date of elvers collected in Moorea (French Polynesia) (poster). -- Lotti Ben Abdallah: Influence of some abiotic factors on the abundances of glass eel Anguilla anguilla (L.) in the estuary of the River Loire, France (abstract). -- C. Belpaire, H Van Driessche, F Y Gao and F Ollevier: Food and feeding activity of glass eel Anguilla anguilla (L.) stocked in earthen ponds. -- Maria Bninska and Marian Leopold: The effect of eel on fish stock composition in lakes- preliminary results. -- Rose M Callaghan and T Kieran McCarthy: Variations in population structure and growth rate of eels in the Dunkellin river system, western Ireland. -- J L Costa, P R Almeida, C Assis, F Moreira and M J Costa: A study of methods of estimating the size of eel populations in small streams. -- Christopher Moriarty: Management of the Corrib eel fishery, Ireland. -- I A Naismith and B Kights: The distribution, density and growth of the European eel Anguilla anguilla (L.) in the River Thames catchment. -- W Russell Poole, Julian D Reynolds and Christopher Moriarty: Age and growth of eel Anguilla anguilla (L.) in oligotrophic streams. -- R H Hadderingh, J W van der Stoep and J M P M Habraken: Deflecting eels from water inlets of power stations with light. -- K Holmgren, H Wickstrom and K Fredga: Growth of eel in a meoscale experiment. -- Aline Caillou, Christian Francisco, Raymonde Lecomte-Finiger and Jean-Marie Salmon: Lipofuscin used as an age indicator in the European eel Anguilla anguilla (L.). Comparison between lipopigment, fluorimetric measurements and otolithometric data (poster). -- Peer Doering, Jiirgen Ludwig and Gerhard Gmel: Prelimary results of otolith amalysis with eels of known age (abstract). -- Antoine Legault: A study of some selectivity factors in eel ladders (abstract). -- F - W Tesch: Insignificance of tidal currents for silver eel migration as studied by eel trac.kings and current measurements. -- F - W Tesch and U Niermann: Stock density of eel larvae Anguilla anguilla (L.) on the European continental slope, based on collections made between 1985 and 1989. -- Takakazu Ozawa, Futoshi Kakizoe, Osame Tabeta, Takashi Maeda and Yasutaka Yuwaki: Larval growth and drift of the Japanese eel Anguilla japonica estimated from leptocephali collections (abstract). -- W-N Tzeng and Y-C Tsai: Otolith microstructural growth patterns and daily age of the eel Anguilla japonica elvers from the estuaries of Taiwan (abstract). -- S Appelbaum and V Birkan: The effect of grading on the growth and distribution pattern in young eels Anguilla anguilla (L.) reared in recirculating systems. -- Inge Boiitius, Karl Otto Wahlstrom and Curt Gelin: Experimentally induced sexual maturity in farmed European eel Anguilla anguilla (L.). -- G. Golombo and G. Grandi: Further experiments in the effects of sex steroids on the gonad sex differentiation of European eel. -- Soeren Hendriksen: Production of eel in recirculation systems in Denmark 1985-1991. -- M Saroglia, C lando Ii, lingle and G Angle: Recent developments in eel farming in Italy. -- Reiner Knosche: An effective biofilter system for eel culture in closed recirculating systems. -- Hao-Ren Lin, Mei-Li Zhang, Lianxi Chen, Glen Van Der Kraak and R E Peter: Effects of sex steroids on gonadotropin synthesis and secretion as well as ovarian development in female Japanese silver eel Anguilla japonica (abstract). -- J Hoglund, J Andersson, H. Wickstrom and M Reizenstein: The distribution of Anguillicola in Sweden and its association with thermal discharge areas. -- J Bosnakovski, K Necev, K Apostolski and M Hristovski: Appearance of eel diseases in Ohrid Lake. Inge Boetius: Development of Anguillicola infestations in some Danish lakes and inlets (abstract).
    • Review of the Irish Salmon Industry

      Went, A. E. J. (Department of Agriculture and Fisheries [Fisheries Division], 1965)
      For centuries the salmon has been an important item of commerce in Ireland and in many parts of the country today it is still very important in the general economy of the people, who gain a living directly or indirectly from it. It is important from two points of view. It provides sport for the angler and it supports a commercial fishery. There are three other articles in this issue: II. SALMON OF THE RIVER SHANNON (1957 to 1962) - Eileen Twomey; III. THE EFFECTS OF ARTERIAL DRAINAGE WORKS ON THE SALMON STOCK OF A TRIBUTORY OF THE RIVER MOY - E.D. Toner, Ann O’Riordan & Eileen Twomey; IV. RECAPTURES OF IRISH TAGGED SALMON OFF GREENLAND - A.E.J. Went.
    • Sea Trout from the Currane Fishery in 1973 and 1974

      Fahy, E. (Department of Agriculture and Fisheries [Fisheries Division], 1980)
      Collections of 1,163 sets of scales from rod-caught sea trout Salma trutta L., made in 1973 and 1974, are described and the results compared with data from previous collections. The mean weight of 821 g was higher than usual in Irish fisheries and smolts were large, ranging from 22.8 to 24.5 cm at two years. Previous indications of a long lived-stock were confirmed by the identification of 37 age categories. The amount of B type growth was considerably less than that observed in samples from rivers with longer estuaries. Marine growth was relatively poor so that the length attained at the end of each sea winter was similar to that of sea trout in other Irish populations. The large size of specimens in the Waterville fishery may therefore be ascribed to longevity rather than to rapid growth at sea. Circuli on parr scales were more numerous than on scales from an east coast sample. Changes observed since the 1944 sampling included an increase in the proportion of older fish indicating that the drift net fishery has not had an adverse effect on the stocks.
    • Sea-Trout from the Tidal Waters of the River Moy

      Fahy, E. (Department of Agriculture and Fisheries [Fisheries Division], 1979)
      Sea trout from the tidal waters of the River Moy are described on the basis of life data and scales from 1,269 specimens collected during 1974 and 1975. The mean smolt age was 2.30 years. Lengths ranged from 16.4 cm for one-year-old A type smolts to 23.9 cm for four-year-old B type fish. Two-year-old smolts increased in length by 67% in their first summer at sea. Sixteen age categories were identified and 82 % of the first spawners were finnock. The proportion of 2. + fish increased throughout the season. Correlation between mean age at first maturation and coefficient of total mortality in British and Irish sea trout stocks was demonstrated. Moy trout are short-lived in the sea and this factor is identified as the most important of those influencing the population which is a typically westem seaboard Atlantic-feeding stock.