• Exploitation and Survival of Reared Salmon Released into the Burrishoole River System

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

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

      Browne, J (Department of Fisheries and Forestry (Trade and Information Section), 1981)
      This leaflet describes the use of a new and highly sophisticated method of tagging salmon. The tag is a microscopic piece of steel carrying a binary-coded number. It is injected into the nose of the young fish and can be recovered at any time subsequently by passing the fish through a magnetic detector. More than 127,000 juvenile salmon were tagged in 1979 and the first of these were recaptured as grilse in the summer of 1981. Research work initiated by Eileen Twomey in 1975 at the Fisheries Research Centre showed that hatchery-reared smolts were making a significant contribution to the national salmon catch. Hatchery-reared fish are recognised by the absence of the adipose fin which is clipped off before the fish are released. The adipose fin is generally thought to be rudimentary and its removal does not seem to affect the fish in any way. The results obtained showed that the proportion of hatchery-reared fish in the commercial catch varied from 2% in the Northwest to 13% on the Clare and Galway coasts. This work gave information on the contribution of hatcheries to the national salmon harvest. The Electricity Supply Board (ESB) have proposals to increase significantly the production of reared smolts for release. It is clearly essential to have information on the survival of hatchery salmon, on the efficiency of various rearing stations and on aspects of husbandry such as the best time for releasing the young fish. This information cannot be obtained by the fin-clipping technique alone but the coded wire tag can provide the answers to many of the vital questions.
    • Population estimates of juvenile salmonids in the corrib system 1980

      Browne, J; Gallagher, P (Department of Fisheries and Forestry, 1981)
      Population assessments of the juvenile salmonids in the Corrib System are being made as part of the overall management plan for the Galway Fishery. In 1980 the first of a series of reports which will be issued annually gave information on the juvenile stocks and on the state of the spawning and nursery tributaries during 1979. Details of the methods used and some background on each of the tributaries were presented. Chemical and biological data on water quality along with numbers, size, age and survival of both salmon and trout are given in Fishery Leaflet 103. During 1979 eight tributaries were surveyed and in two cases upstream and downstream reaches were examined. In 1980 the effort in terms of personnel and equipment was increased but the high rainfall during the period of work, from mid-July to mid-September, meant that only two further stations were studied, one on the Dalgan river and the other on the Balinbrack river. The methods used and the scope of the work were identical in 1979 and 1980. In these assessments the emphasis is on salmon type tributaries and salmon type habitats within these tributaries so that trout numbers could be expected to be low.
    • Population estimates of juvenile salmonids in the Corrib system 1981

      Browne, J; Gallagher, P (Department of Fisheries and Forestry (Trade and Information Section), 1982)
      This is the third in a series of reports regarding the stocks of juvenile salmonids in the Corrib system. During the 1981 season fourteen tributaries were surveyed and in two cases upstream and downstream reaches were examined. These included three which had not been studied previously: the Failmore, Letterfore and Black. The methods were identical to those used in 1979 and 1980. As in the previous years the rivers were selected because they were known salmon holding tributaries and do not reflect trout numbers in the system. The population numbers are assessed by electrically fishing a selected area. The fish caught are marked by fin clipping and allowed to re-mix with the fish in the stream. The next day fishing is repeated in the same place and the proportion of marked to unmarked fish gives an estimate of the population. While it is not essential that river conditions remain the same on both days it does help the accuracy of the estimate. There is a tendency for fish to move out of their home territories during floods. Population surveys yield the best results when a large proportion of the tagged fish are recovered. Ideal electro fishing conditions are low water, overcast sky and similar river conditions on both days.
    • Populations Estimates of Juvenile Salmon in the Corrib System from 1982 to 1984

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

      Browne, J; Gallagher, P (Department of Fisheries and Forestry (Trade and Information Section), 1980)
      Population assessments of the juvenile salmonids in the Corrib system are being made as part of the overall management plan for the Galway Fishery. This leaflet is the first of a series of reports which will be issued annually to give up-to-date information on the stocks and on the state of the tributaries used for spawning and nursery grounds. Eight tributaries were surveyed in 1979 and in two cases an upstream and a downstream reach were examined.
    • Preliminary Results of Salmon Tagging in the Killala Bay Area 1977

      Browne, J (Department of Fisheries (Trade and Information Section), 1978)
      Salmon movements in and around Killala Bay in 1977 were investigated by tagging. A total of 40 tags (20%) were returned. The areas of recovery ranged from the River Shannon to the south coast of England.
    • Recaptures of Adult Salmon tagged as smolts at Carrigadroghid

      Browne, J; Doyle, J (Department of Fisheries and Forestry (Trade and Information Section), 1979)
      A total of 2936 salmon were tagged at Carrigadroghid Co Cork in January 1973. From this tagging there were 34 recaptures, a return rate of 1.16%. In 1975 the number of salmon smolts tagged was 4860 and 18 were recovered, representing a return rate of 0.37%. Details of the recaptures resulting from these two tagging operations are given.
    • Recaptures of Irish Tagged Salmon off Greenland

      Browne, J (Department of Agriculture and Fisheries (Fisheries Division), 1977)
      Since tagging of smolts began in Ireland there have been sixteen distant water recaptures of adult salmon tagged as smolts or parr in Irish waters. Fifteen of these were recaptured from the Greenland fishery and one salmon was recovered from the Faroe Islands. The recaptures resulted from a number of salmon smolt and salmon parr tagging programmes. Some of these programmes were designed specifically to obtain information on the distant migrations of Irish salmon but other programmes were to study migrations and mortality in the home waters. Information on recaptures has been published elsewhere (Piggins 1970, Went 1973). This leaflet brings together all the available information on recaptures of tagged Irish salmon in distant waters up to December 1975 and gives background information on the tagging programmes.
    • Results of Magnetic Tag Recovery Programme in the Mayo Area in 1986

      Gallagher, P; Browne, J (Department of the Marine, 1987)
      Young salmon are tagged at various locations throughout the country with coded wire tags. They are released at different times of the year, and in various river systems to establish the best time of year and the best locations for release. The majority of the tagged fish are hatchery reared, the only exception being in the Corrib and Blackwater rivers where wild smolts are tagged. All micro-tagged fish are adipose fin clipped. Some hatcheries also use an adipose fin clip to mark their reared fish. Twenty nine thousand net caught salmon were examined at a number of locations in Mayo. All fish with adipose fin clips were screened with a magnetic tag detector. A total of 736 tags were recovered from which it was estimated that rearing stations contributed over 1,300 fish to the north Mayo catch.
    • Results of Salmon tagging in the Killala Bay area, 1976

      Browne, J (Department of Fisheries (Trade and Information Section), 1978)
      Salmon movements in and around Killala Bay were investigated by tagging. A total of 49 tags (17.07%) were returned. The areas of recovery ranged from the Kerry coast to the Scottish west coast. A high proportion of the tags recovered from the River Moy were from fish tagged at stations to the east of Killala Bay.