• Activity patterns of some inshore fishing vessels in 2006-2007

      Fahy, E.; Fee, D.; O'Connor, S.; Smith, T. (Marine Institute, 2007)
      Observations of daily “absence-from-port” patterns and indications of gears used were carried out on 147 vessels ranging from 5 to 13 m overall length, between April 2006 and March 2007 at three ports in west, southwest and southern Ireland. The vessels numbered approximately 6% of the total national fleet and they were larger than the average length of boats observing a daily working “absence-from-port” pattern. Fishing gears belonged to one of five categories: shellfish dredges, nets, hook and line, pots and otter trawl. More than half of the vessels observed did not carry any indication of fishing gear; 46 % had evidence of using one gear and 3% showed signs of using two. Activity (absence) patterns were low, ranging between 14 and 42 % of week-days on which observations were made. The annual pattern of gear usage described by BIM in 1999 was not apparent in any of the three ports. Instead, the local availability of fishing opportunities was influential in deciding which methods predominated. In only one port was there a marked seasonal activity pattern. Visible signs of vessel registration were similar to the situation in 2002.
    • 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 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.
    • 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.
    • A preliminary account of fisheries for the surf clam Spisula solida (L) (Mactracea) in Ireland

      Fahy, E.; Carroll, J.; O'Toole, M.; Hickey, J. (Marine Institute, 2003)
      Surf clams from seven stocklets on the west and south coasts are examined to provide a preliminary account of the fishery in Ireland. Spisula solida is the species harvested in every case. Most of the material was collected by commercial (box or hydraulic) dredge. A quantitative account of a surf clam bed is based on sampling by Day grab in Waterford Harbour. Ageing was by external shell sculpture. A limited comparison of this method with ageing by internal shell structure confirmed the method was usable and the results are presented on this basis with, however, reservations on the reliability of the approach. S. solida in Ireland had Linf of c 43 cm. Material gathered in Clifden, Co Galway, had an Linf of 35 mm. The Clifden stocklet was heavily fished when the material was gathered and a low value for Linf is attributed to the Lee phenomenon. A growth curve is constructed for only one stocklet, that in Waterford Harbour. Growth was slower than for S. solida in the North Sea, a possible consequence of heavy fishing also. The clam bed in Waterford Harbour was a low elevation bank of coarse (Spisula) sand. The area of the bed had become reduced during the preceding year by the invasion of silt grades displaced by earthworks upstream; these were injected into the coarse material to form a perimeter of the clam patch. Within the bed, the highest biomass of S. solida was 600 g/sq.m. Representation of age frequencies within samples suggests that heavy spatfalls of S. solida occur at irregular intervals and this complicates the calculation of F values from a catch curve. A yield per recruit curve is prepared for the clam patch in Waterford Harbour.
    • 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.
    • 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.
    • 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.
    • Some thick shelled whelk Buccinum undatum characteristics and fisheries in Ireland

      Fahy, E.; Grogan, S.; Byrne, J.; Carroll, J. (Marine Institute, 2006)
      Observations are presented on two whelk populations from the Cape grounds in Co. Donegal and the vicinity of Helvic Head Co. Waterford. Both co-exist with large populations of brown crab (Cancer pagurus) which is the likely explanation for their thick shells. In the south west Irish Sea (with which comparison is made) and in the Cape stocks, 83-88% of individuals were easily aged by reference to the operculum. Heavy calcification obscured structure in the case of Helvic animals and only 6% of these could be confidently aged. Helvic and south west Irish Sea whelk have similar L∞, but both Helvic and Cape whelk have more rapid early growth than in the Irish Sea. The density of whelk in the Helvic vicinity is insufficient to support a commercial fishery. The yield of whelk from other areas of the Celtic Sea is sporadic and slow to recover from exploitation. The Cape fishery shows signs of rapid depletion since most recent exploitation began there in 2003. The centrally situated sectors of the south west Irish Sea fishery are highly resilient and recover rapidly from heavy removals of biomass which can exceed 50% per annum. Maturation appears to take place at a lower size and age in the Irish Sea than in the other two whelk stocks and this is tentatively proposed as the explanation for their lower productivity.
    • 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.
    • 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.
    • The status of the inshore component of the northern brown crab Cancer pagurus fishery, assessed from a time series of LPUE constructed from historical sources

      Meredith, D.; Fahy, E. (Marine Institute, 2005)
      A 27 year LPUE series was compiled from daily landings and creel numbers fished, as reported by a processor and by personnel participating in the activities of a small inshore fleet at Malin Head, Co. Donegal. The fleet targeted brown crab in the late summer and autumn months and the series was compared with two other series of LPUE constructed from data obtained from two fleet sources fishing the same stock. The most significant event to have taken place since records commenced in the late 1970s was the introduction in the 1990s of a small vivier offshore crabbing fleet. Competition between the inshore and offshore components intensified and the inshore fleet responded by further capitalising and increasing its seaward range. Since the mid-1980s the number of boats in the Malin Head inshore fleet pursuing the autumn fishery halved while the total amount of gear increased by 29%. The number of pots set by a vessel in a day averaged 600 in 2004 but in 2000 the practice of fishing two sets of gear simultaneously became established. The vivier boats also moved inshore and the ranges of the two fleets now overlap. In the past 15 years there was a loss of between 37 and 57% LPUE, according to the data assembled in this work. Schaefer analyses carried out on the inshore Malin Head fleet’s results and extended to cover the estimated landings of the Donegal inshore fleet, indicate that maximum sustainable yield was almost reached and that the F0.1 point was exceeded by both fleets. Any additional increase in F is likely to further accelerate decline in LPUE. The stock is regarded as being close to over-fished in a regime without effective effort controls. The problems associated with managing a fishery of this kind are briefly discussed.
    • 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.
    • 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.
    • 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.