• The cockle Cerastoderma edule (L.) on the South Bull, Dublin Bay: population parameters and fishery potential

      West, A B; Partridge, J K; Lovitt, A (Department of Fisheries and Forestry, 1979)
      The history of the Dublin Bay cockle fishery is reviewed briefly with emphasis on the period 1893-1913. Prior to 1900 some 80 tonnes of cockles are said to have been landed annually. In the subsequent decade the fishery declined and in recent times has been defunct. The population of cockles on the South Bull, Dublin Bay, was investigated in 1971 and 1972. Cockles were distributed throughout the beach, but occurred in greater density in the mid-shore region. The mean density, however, was low (9-13 cockles per sq.m) and the maximum recorded was only 51 per sq.m; this is consistent with the relatively exposed nature of the beach. The population was dominated by 0+ and 1+ age groups, though cockles as old as 9+ were collected. The age structure was consistent with regular annual recruitment, and the mean mortality figure for cockles in their second, third, fourth and fifth years was Z=0.76. The mean lengths at the end of the first four winters were 6.5, 22, 28.5 and 32 mm. The value of L∞ was 40 mm, and K = 0.6. The relationships between shell lengths and the weights of the shell, dry meat, wet meat, and shell + wet meat are described. The potential of this cockle population for commercial exploitation is considered, although in view of the low population density the catch per unit effort would probably be too small to be commercially viable at present. Yield curves indicate that a minimum legal length of 24 mm would be appropriate for protection of the breeding stock while allowing the optimum yield to be obtained. The potential sustained yield of the beach was estimated at 4 tonnes/sq.km annually at a fishing mortality of F=0.10.
    • Combined oral toxicity of azaspiracid-1 and yessotoxin in female NMRI mice

      Aasen, J A B; Espenes, A; Miles, C O; Samdal, I A; Hess, P; Aune, T (Elsevier, 2011)
      For many years, the presence of yessotoxins (YTXs) in shellfish has contributed to the outcome of the traditional mouse bioassay and has on many occasions caused closure of shellfisheries. Since YTXs do not appear to cause diarrhoea in man and exert low oral toxicity in animal experiments, it has been suggested that they should be removed from regulation. Before doing so, it is important to determine whether the oral toxicity of YTXs is enhanced when present together with shellfish toxins known to cause damage to the gastrointestinal tract. Consequently, mice were given high doses of YTX, at 1 or 5 mg/kg body weight, either alone or together with azaspiracid-1 (AZA1) at 200 μg/kg. The latter has been shown to induce damage to the small intestine at this level. The combined exposure caused no clinical effects, and no pathological changes were observed in internal organs. These results correspond well with the very low levels of YTX detected in internal organs by means of LCMS/MS and ELISA after dosing. Indeed, the very low absorption of YTX when given alone remained largely unchanged when YTX was administered in combination with AZA1. Thus, the oral toxicity of YTX is not enhanced in the presence of sub-lethal levels of AZA1.
    • The commercial exploitation of shrimp Palaemon serratus (Pennant) in Ireland

      Fahy, E.; Gleeson, P. (Marine Institute, 1996)
      Palaemon serratus is at the northern limit of its range in the British Isles. In Ireland it is most abundant in the southwest where it has been commercially fished since the mid-1970s. Landings in recent years have averaged between 200 and300 tonnes annually with an estimated export value of £2—3 m. These landings represent a three-fold expansion over those of the previous decade. The biology of the species was investigated over a 12 month period in Bantry Bay using commercial gear. At most times of the year there is a bimodal length frequency distribution and the life expectancy is interpreted as 2 years. Condition factor does not vary much during the year in males and immature females but the larger females put on up to 30% weight in the autumn. The reproductive cycle in Bantry resembles that in the south of England rather than that in north Wales, these two locations providing earlier studies of the species. The largest females come into berry in October and egg carriage within the population continues into the following summer; in May, a second group of smaller females, belonging to the 0 age group, carries eggs. Corroborative evidence for this interpretation is provided by the size of the ova and their developmental state. There would appear to be an influx of shrimp to Bantry Bay which builds up from May and declines after January but cohort and gender migrations are unclear. Catch per unit of fishing effort (cpue) is estimated from the weight of a consignment of shrimp delivered to a processor. Such data are variable but they are also consistent and stable over the short-term and throughout the range of shrimp fisheries. A time series from 1977 to 1994 suggests a 36% decline; the significance of this is not known. Shrimp fishing takes place during the autumn and winter months. In the southeast landings are taken throughout the year but those outside the period August to January, inclusive, do not exceed 8% of the total. In the southwest only 3% of landings are made outside these months, while in Connemara none was reported Mechanical grading in the factory is explored as a means of reconstructing age profiles. Two patterns of exploitation are described: that of the southwest and southern coast has a larger proportion of 0 group shrimp which may reach 40% by numbers of the total landings; in Connemara the proportion of 0 group shrimp is much smaller. Attempts are made to find some method of predicting aspects of the catch from biological and sea temperature data. There is a suggestion that a large brood year is influential in producing a successor whose size is estimated 2 years later. The sustainability of the shrimp fishery is unknown and two precautionary measures are suggested as the basis of a management regime: enlarging the mesh size to improve the exploitation pattern and limiting the fishing season.
    • Comparative effects of the marine algal toxins azaspiracid-1, -2, and -3 on Jurkat T lymphocyte cells

      Twiner, M.; El-Ladki, R.; Kilcoyne, J.; Doucette, G.J. (ACS Publications, 2012)
      Azaspiracids (AZA) are polyether marine toxins of dinoflagellate origin that accumulate in shellfish and represent an emerging human health risk. Although monitored and regulated in many European and Asian countries, there are no monitoring programs or regulatory requirements in the United States for this toxin group. This did not prove to be a problem until June 2009 when AZAs were identified in US seafood for the first time resulting in human intoxications and further expanding their global distribution. Efforts are now underway in several laboratories to better define the effects and mechanism(s) of action for the AZAs. Our investigations have employed Jurkat T lymphocyte cells as an in vitro model to characterize the toxicological effects of AZA1, AZA2, and AZA3. Cytotoxicity experiments employing a metabolically based dye (i.e., MTS) indicated that AZA1, AZA2, and AZA3 each elicited a lethal response that was both concentration- and time-dependent, with EC50 values in the sub- to low nanomolar range. On the basis of EC50 comparisons, the order of potency was as follows: AZA2 > AZA3 > AZA1, with toxic equivalence factors (TEFs) relative to AZA1 of 8.3-fold and 4.5-fold greater for AZA2 and AZA3, respectively. Image analysis of exposed cells using Nomarski differential interference contrast (DIC) imaging and fluorescent imaging of cellular actin indicated that the morphological effects of AZA1 on this cell type are unique relative to the effects of AZA2 and AZA3. Collectively, our data support the growing body of evidence suggesting that natural analogues of AZA are highly potent and that they may have multiple molecular targets.
    • Comparison of the effects of exploitation on theoretical long-lived fish species with different life-history strategies and the implications for management

      Codling, E.A.; Kelly, C.J.; Clarke, M. (International Council for the Exploration of the Sea (ICES), 2005)
      A stage-based simulation model is used to investigate the effect of exploitation on theoretical populations representing long-lived elasmobranch and teleost species with different life-history strategies. A comparison is made between the effect of exploitation on the elasmobranch ‘k-strategists’ and other teleost species that are ‘r-strategists’. We demonstrate the effects of stage-based exploitation on a typical long-lived elasmobranch population and discuss the implications of this when designing a management plan to ensure survival of the stock.
    • A Comparitive Limnological Study of Two Irish Lakes (Lough Sillan, Co. Cavan and Lough Dan, Co. Wicklow).

      O'Connor, J. P.; Bracken, J .J. (Department of Agriculture and Fisheries [Fisheries Division], 1978)
      A comparative study of Lough Sillan (Co. Cavan) and Lough Dan (Co. Wicklow) revealed that these two Irish lakes differ markedly in their physicoRchemical and faunal characteristics. The possible causes of these observed dissimilarities are reviewed and discussed. Lough Sillan may be classified as moderately eutrophic while Lough Dan is both humic and oligotrophic.
    • Compilation of Habitat-Based Catchment Information and Historical Eel Data in Support of Eel Management Plans ‘EEL-PLAN’ – Final Summary Report

      Compass Informatics Ltd; Inland Fisheries Ireland; National University of Ireland, Galway (Marine Institute, 2011)
      The overall aim of the project was to establish an information management framework for the development of River Basin Eel Management Plans (EMP). This involved the collation of base information to assist the publication of the initial National Plan (DCENR 2008) and, importantly, the establishment of a GIS and database system for continued information collation, analysis, management and planning. This report is the summary report of this project.
    • Compilation of Habitat-Based Catchment Information and Historical Eel Data in Support of Eel Management Plans ‘EEL-PLAN’ – Final Technical Report

      Compass Informatics Ltd; Inland Fisheries Ireland; National University of Ireland, Galway (Marine Institute, 2011)
      The overall aim of the project was to establish an information management framework for the development of River Basin Eel Management Plans (EMP). This involved the collation of base information to assist the publication of the initial National Plan (DCENR 2008) and, importantly, the establishment of a GIS and database system for continued information collation, analysis, management and planning. This report is the full technical report of this project.
    • Complex pattern of genetic structuring in the Atlantic salmon (Salmo salar L.) of the River Foyle system in northwest Ireland: disentangling the evolutionary signal from population stochasticity

      Ensing, Dennis; Prodöhl, Paulo A.; McGinnity, Philip; Boylan, Patrick; O’Maoiléidigh, Niall; Crozier, Walter W. (Blackwell Publishing Ltd., 2011)
      Little is known about the microevolutionary processes shaping within river population genetic structure of aquatic organisms characterized by high levels of homing and spawning site fidelity. Using a microsatellite panel, we observed complex and highly significant levels of intrariver population genetic substructure and Isolation-by-Distance, in the Atlantic salmon stock of a large river system. Two evolutionary models have been considered explaining mechanisms promoting genetic substructuring in Atlantic salmon, the member-vagrant and metapopulation models. We show that both models can be simultaneously used to explain patterns and levels of population structuring within the Foyle system. We show that anthropogenic factors have had a large influence on contemporary population structure observed. In an analytical development, we found that the frequently used estimator of genetic differentiation, FST, routinely underestimated genetic differentiation by a factor three to four compared to the equivalent statistic Jost's Dest (Jost 2008). These statistics also showed a near-perfect correlation. Despite ongoing discussions regarding the usefulness of “adjusted” FST statistics, we argue that these could be useful to identify and quantify qualitative differences between populations, which are important from management and conservation perspectives as an indicator of existence of biologically significant variation among tributary populations or a warning of critical environmental damage.
    • Concentration of norovirus during wastewater treatment and its impact on oyster contamination

      Flannery, John; Keaveney, Sinéad; Rajko-Nenow, Paulina; O’Flaherty, Vincent; Doré, William (American Society for Microbiology, 2012)
      Concentrations of E. coli, FRNA bacteriophage, norovirus genogroup I (NoV GI) and II (NoV GII) in wastewater were monitored weekly over a one-year period at a wastewater treatment plant (WWTP) providing secondary treatment. A total of 49 samples of influent, primary and secondary-treated wastewater were analyzed. Using a real-time RT-qPCR, mean NoV GI and NoV GII concentrations detected in effluent wastewater were 2.53 and 2.63 log10 virus genome copies 100 ml-1 respectively. Mean NoV concentrations in wastewater during the winter period (January to March inclusive) (n=12) were 0.82 (NoV GI) and 1.41 (NoV GII) log units greater than mean concentrations for the rest of the year (n=37). The mean reduction of NoV GI and GII during treatment was 0.80 and 0.92 log units respectively with no significant difference detected in the extent of NoV reductions due to season. No seasonal trend was detected in the concentrations of E. coli or FRNA bacteriophage in wastewater influent and showed mean reductions of 1.49 and 2.13 log units respectively. Mean concentrations of 3.56 and 3.72 log10 virus genome copies 100 ml-1 for NoV GI and GII respectively were detected in oysters sampled adjacent to the WWTP discharge. A strong seasonal trend was observed and concentrations of NoV GI and GII detected in oyster were correlated with concentrations detected in the wastewater effluent. No seasonal difference was detected in concentrations of E. coli or FRNA bacteriophage detected in oysters.
    • The Conditions for Successful Oyster Culture

      Fowler, G. H.; The Department of Agriculture and Technical Instruction for Ireland (London: Dulau & Co., 1893)
      A lecture delivered by G. H. Fowler on the conditions for successful oyster culture at the Cornish Fisheries Exhibition in 1893.
    • Contaminants in marine biota 1990 monitoring programme

      Nixon, E R; McLaughlin, D; Boelens, R G; O'Sullivan, G (Department of the Marine, 1991)
      In 1990, samples of fish from commercial catches landed in Ireland, and fish and shellfish collected at Irish coastal sites, were analysed in accordance with the requirements of the Joint Monitoring Programme (JMP) of the Oslo and Paris Commissions (OSPARCOM). The methodologies employed were consistent with JMP Purpose A: Significance to human health, and JMP Purpose C: Existing geographical distributions. The levels of heavy metals and chlorinated hydrocarbon compounds were generally low: well below the internationally accepted levels for protection of human health, and below the levels known to be of significance to marine life. Higher than Irish average levels were found in areas such as Dublin Bay, Cork Harbour, Mornington on the river Boyne, and the Barrow and Rogerstown Estuaries. These are all adjacent to densely populated and industrialised catchments and coasts. There were no cases of serious contamination.
    • Contrasting responses to selection in class I and class IIα major histocompatibility-linked markers in salmon

      Consuegra, S; De Eyto, E; McGinnity, P; Stet, R.J.M.; Jordan, W.C. (Nature Publishing Group, 2011-08)
      Comparison of levels and patterns of genetic variation in natural populations either across loci or against neutral expectation can yield insight into locus-specific differences in the strength and direction of evolutionary forces. We used both approaches to test the hypotheses on patterns of selection on major histocompatibility (MH)-linked markers. We performed temporal analyses of class I and class IIα MH-linked markers and eight microsatellite loci in two Atlantic salmon populations in Ireland on two temporal scales: over six decades and 9 years in the rivers Burrishoole and Delphi, respectively. We also compared contemporary Burrishoole and Delphi samples with nearby populations for the same loci. On comparing patterns of temporal and spatial differentiation among classes of loci, the class IIα MH-linked marker was consistently identified as an outlier compared with patterns at the other microsatellite loci or neutral expectation. We found higher levels of temporal and spatial heterogeneity in heterozygosity (but not in allelic richness) for the class IIα MH-linked marker compared with microsatellites. Tests on both within- and among-population differentiation are consistent with directional selection acting on the class IIα-linked marker in both temporal and spatial comparisons, but only in temporal comparisons for the class I-linked marker. Our results indicate a complex pattern of selection on MH-linked markers in natural populations of Atlantic salmon. These findings highlight the importance of considering selection on MH-linked markers when using these markers for management and conservation purposes.
    • The Contribution of Hatchery-Reared Smolts to the Irish Drift Net Fishery

      Twomey, E (Department of Fisheries and Forestry, 1982)
      This Leaflet gives the results of the examination of 104,851 salmon caught by the drift nets between 1978 and 1981. The majority of salmon taken in the Irish commercial fishery are caught by drift nets. The drift net fishery takes place in coastal waters from May onwards and exploits, in the main, one sea-winter fish. In order to quantify the contribution of hatchery reared smolts to the fishery, the commercial catch was sampled at various landing sites between 1978 and 1981. The results obtained showed that the reared fish were randomly distributed in the drift net catch around the coast from Malin Head to Ardmore Bay. The highest contribution (12.9%) was found in the fish captured along the Galway and South Mayo coasts. The next highest contribution was in West Cork where 6.3% of the fish sampled were recorded as reared. The analysis of each day's sample throughout the season indicated that the reared fish arrived concurrently with the wild salmon. A calculation of the value of the salmon which were derived from hatchery-reared smolts was made, based on the percentage of reared fish observed in the catch samples. The conclusion was drawn that, although the contribution of reared smolts to the total catch is small, the principle of artificial rearing of smolts is justified in view of the contribution to the national catch and the spawning stock.
    • Cork Harbour PSP incident

      Doyle, J.; Dunne, T. (1985)
      Gonyaulax tamarensis is one of the principle organisms involved in Paralytic Shellfish Poisoning in Europe and North America. P.S.P. has not been described in Irish waters with the exception of one incidence in Belfast Lough and also in Kerry in the late 1800s, although this cannot be verified. G. tamarensis has only been recorded in Irish waters as individual organisms and no bloom has been described up to this.
    • Crawfish Investigations 1966-68

      Molloy, J P (Department of Agriculture and Fisheries (Fisheries Division), 1970)
      The fishery for crawfish (Palinurus elephas) in Irish waters has previously been described by Gibson and O'Riordan (1965) and by Gibson (1967). Molloy (1968) has given some details of the scientific work done on this species in recent years. One of the most important aspects of this fishery is that both lobsters and crawfish are exploited simultaneously by boats which use the same type of traps and baits for the two species. Neither the location nor extent of the fishery has shown any marked change since it first became an important aspect of the Irish fishing industry but the annual landings still show considerable variations. These fluctuations in the yearly catch would seem to depend more on the duration of the season and its length, rather than on changes in stock abundance (Gibson 1967). The annual landings (to the nearest thousand fish) since 1951 are shown. The landings in 1968 were surprisingly low for a season which was marked by exceptionally fine weather.
    • The Crayfish Astacus pallipes of an Irish Lake

      Moriarty, C. (Department of Agriculture and Fisheries [Fisheries Division], 1971)
      The population of a 30 hectare limestone lake was studied. The crayfish were most active from July to September. Females carrying eggs were present from November to June. Parameters describing the measurements of the stock available for trapping were determined.
    • Creating a newsletter or newspaper.

      Marine Institute (Marine Institute, 2013)
      Creating a class newsletter, students will build their vocabulary and writing skills through drafting, revising, editing, and publishing. Students will become familiar with the process of producing formal written documents, such as magazines and newspapers. Through interacting with others in the class, students will also learn how to work within a team.
    • Creating a weekly Harmful Algal Bloom bulletin

      Leadbetter, A.; Silke, J.; Cusack, C. (Marine Institute, 2018)
      This document describes the procedural steps in creating an information product focused on toxic and harmful phytoplankton. The product is an online Harmful Algal Bloom (HAB) bulletin for aquaculturists, who can face serious operational challenges in the days after a HAB event. Data from satellite, numerical hydrodynamic models and In-situ ocean observations are organised and presented into visual information products. These products are enhanced through local expert evaluation and their interpretation is summarised in the bulletin. This document aims to provide both process overviews (the “what” of the Best Practice in producing the bulletins) and detail procedures (the “how” of the Best Practice”) so that the bulletins may be replicated in other geographic regions.