• The abundance of boarfish (Capros aper) along the western shelf estimated using hydro-acoustics

      O'Donnell, C.; Farrell, E.; Saunders, R.; Campbell, A. (Marine Institute, 2012)
      The Boarfish (Capros aper, Linnaeus) is a relatively small deep bodied fish growing up to 23 cm in total length. Typically reddish in colour with large eyes and a highly protrusible mouth boarfish are known to inhabit shallow shelf seas to shelf slopes from 40-600 m. Boarfish are a mesopelagic shoaling species distributed in the eastern Atlantic from Norway to Senegal including the Mediterranean. Exploratory fishing for boarfish by Irish vessels began in the later 1980s when commercial quantities were encountered during the spring horse mackerel (Trachurus trachurus) and mackerel (Scrombrus scomber) fishery in northern Biscay. During the early 2000s the Irish landings were relatively small (<700 t per yr) and it was not until 2006 that a directed fishery developed in earnest. Landings peaked in 2010 at over 137,000 t prior to the introduction of TAC control and interim management plan. This survey represents the first dedicated exploratory acoustic survey for boarfish (Capros aper) undertaken along the western seaboard of Ireland. The survey was timed to coincide with peak spawning time as determined from histological analysis of commercial catch samples. Area coverage was based on the distribution of catches from the IBTS survey time series and from catch data from the pelagic fleet targeting boarfish since 2005. In total 3,160 nmi (nautical miles) of cruise track was undertaken by the MFV Felucca, over 32 transects relating to an area coverage of over 89,500 nmi². Coverage extended from the 50 m contour to the shelf slope (250 m). Transect spacing was set at 15 nmi throughout to make best use of the time available and the large geographical area to be covered. The results presented here are a composite of data collected during this survey and on the northwest herring survey (RV Celtic Explorer). Both surveys were timed to link up and were carried out over 33 days from north (59°N) to south (47°30’N). Acoustic data were collected using a Simrad EK 60 scientific echosounder via a Simrad ES-38B (38 KHz) split-beam transducer which was mounted within a tow-body. This configuration was calibrated on the survey vessel prior to departure. An age length key (ALK) compiled primarily from commercial samples collected during 2010 was applied during the analysis of survey data. Age distribution indicate that the stock was dominated by the following age classes in terms of abundance: 6, 7, 20+ and 9 year old fish and 20+, 9, 7 and 10 years in terms of biomass respectively. Immature fish from 0-2 years were poorly represented in survey catches and this is consistent with a spawning movement of mature stock away from feeding grounds on the shelf. During the survey boarfish shoals were primarily distributed along the shelf edge occurring as aggregations actively spawning or in a state of near readiness to spawn. As a result the abundance estimate is almost exclusively composed of mature individuals (>99%) which is in contrast to the primarily on-shelf distribution of commercial catches. The biomass and abundance estimates presented here were calculated using a modelled TS-length relationship, from as yet unpublished data for boarfish and applied retrospectively to acoustic data.
    • Achieving EU Standards in Recreational Waters

      Bruen, M P; Crowther, J; Kay, D; Masterson, B F; O'Connor, P E; Thorp, M B; Wyer, M D; Chawla, R. (Marine Institute, 2001-11)
      In the interest of public health and amenity, the quality of bathing waters is controlled by the European Union Bathing Water Directive (1976); the well-known Blue Flag scheme is associated with this. The Directive regulates — among other parameters — the numbers of “indicator bacteria” permitted in the water; these microorganisms themselves are not an apparently significant risk to health, but they act as indicators that sewage-derived pathogenic organisms that cause illness may be present. Coastal and freshwater bathing areas are monitored regularly during the bathing season for compliance with the Directive, and the published annual reports attract much public and news-media attention. Substantial high-cost improvements to sewerage management infrastructure have been made by Local Authorities both in Ireland and Wales aimed at achieving better compliance with bathing water standards. Nevertheless, there have been continuing episodic failures to meet the indicator-bacteria standards. Recent research in the United Kingdom has indicated that substantial quantities of the offending indicator bacteria may be conveyed in surface water runoff from the catchments of rivers and small streams in response to rainfall events. There have been indications too that the use to which land in a catchment is put (pasture, forestry, urban, and so on) is reflected in the levels of indicator bacteria contributed by the land to water. Two principal questions arise: 1. Are failures to meet microbial water-quality standards for bathing areas due to rainfall-related runoff from adjacent catchments? 2. If so, is this effect related to land uses in the catchments? This report gives an account of work addressing these issues conducted in the Afon Rheidol and Afon Ystwyth catchments in north Ceredigion, Wales and in the Dargle catchment in north Co. Wicklow, Ireland. The catchments in both areas drain to the sea through harbour outlets close to bathing beaches, and the beaches have had imperfect compliance with the Bathing Water Directive in the past.
    • Acidification and its effect on the ecosystems of the ICES Area

      Fernand, L.; LeQuesne, W.; Silke, J.; Li, B.; Kroeger, S.; Pinnegar, J.; Fossä, J.H.; Morán, X.A.G. (ICES, 2011)
      This focuses on the impacts of ocean acidification (OA) on ecosystems and higher trophic levels in the ICES Area. One of ICES distinguishing features is its access to scientists across the entire marine field. This report is based on the Report of the Workshop on the Significance of Changes in Surface CO2 and Ocean pH in ICES Shelf Sea Ecosystems (WKCpH; ICES, 2007c), updated to include recent research, using inputs from the chairs of ICES working groups. Oceanic uptake of atmospheric CO2 has led to a perturbation of the chemical environment, primarily in ocean surface waters, which is associated with an increase in dissolved inorganic carbon (DIC). The increase in atmospheric CO2 from ca. 280 ppmv (parts per million by volume) 200 years ago to 390 ppmv today (2011) has most probably been caused by an average reduction across the surface of the oceans of ca. 0.08 pH units (Caldeira and Wickett, 2003) and a decrease in the carbonate ion (CO32−) of ca. 20 μmol kg −1 (Keshgi, 1995; Figure 5.1). It has been estimated that the level could drop by a further 0.3 – 0.4 pH units by the year 2100 if CO2 emissions are not regulated (Caldeira and Wickett, 2003; Raven et al., 2005). A study of potential changes in most of the North Sea (Blackford and Gilbert, 2007) suggests that pH change this century may exceed its natural annual variability. Impacts of acidity induced change are likely, but their exact nature remains largely unknown, and they may occur across the whole range of ecosystem processes. Most work has concentrated on open‐ocean systems, and little research has been applied to the complex systems found in shelf‐sea environments.
    • Acoustic Based Cetacean Detection

      McKeown, E. (Marine Institute, 2010)
      Final report of a project that identified the physical parameters associated with monitoring, tracking and positioning of marine mammals, principally cetaceans (whales and dolphins), in order to develop a small-scale detection system to demonstrate that the presence of specific marine mammals within a defined radius in shallow waters.
    • An Acoustic Survey of Orange Roughy Aggregations to the West and North of the Porcupine Bank

      O'Donnell, C.; Macaulay, G.; Sheppard, S.; Doonan, I.; Mackey, M.; Ullgren, J.; Grehan, A.; Sachetti, F.; Haride, N. R. (Marine Institute, 2007)
      The survey was carried out over a 14 day period from the 5th – 20th February 2005 onboard the 65m RV Celtic Explorer. The main focus of this pilot survey was to acoustically survey orange roughy (Hoplostethus atlanticus) spawning aggregations.
    • 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.
    • Advanced Spatial Modeling to Inform Management of Data-Poor Juvenile and Adult Female Rays

      Dedman, Simon; Officer, Rick; Brophy, Deirdre; Clarke, Maurice; Reid, David G. (MDPI AG, 2017)
      Chronic overfishing has depleted numerous elasmobranch stocks in the North East Atlantic, but addressing this issue has been hampered by management complications and lacking data. Spatial management approaches have thus been advocated. This work presents a novel application and further development of an advanced spatial modeling technique to identify candidate nursery grounds and spawning areas for conservation, by subsetting already limited data. Boosted Regression Tree models are used to predict abundance of juvenile and mature female cuckoo (Leucoraja naevus), thornback (Raja clavata), blonde (Raja brachyura), and spotted (Raja montagui) rays in the Irish Sea using fish survey data and data describing fishing pressure, predation and environmental variables. Model-predicted spatial abundance maps of these subsets reveal distinct nuances in species distributions with greater predictive power than maps of the whole stock. These resulting maps are then integrated into a single easily understood map using a novel approach, standardizing and facilitating the spatial management of data-limited fish stocks.
    • Advances in Fish Biology in Ireland

      Moriarty, C. (Department of Agriculture and Fisheries [Fisheries Division], 1983)
      Due to little information exchange between Irish freshwater biologists, a seminar was was held to help broaden and share the knowledge of those participating in professional or amateur freshwater biology in Ireland.
    • The advantages of the use of discs containing single agents in disc diffusion testing of the susceptibility of Aeromonas salmonicida to potentiated sulphonamides

      Douglas, I.; Ruane, N.M.; Geary, M.; Carroll, C.; Fleming, G.T.A.; McMurray, J.; Smith, P. (Elsevier, 2007)
      The susceptibilities of 106 strains of Aeromonas salmonicida to trimethoprim/sulfamethoxazole (SFT) were determined in two laboratories using the Clinical and Laboratory Standards Institute's M42-A disc diffusion protocols. The data generated by the use of discs containing 25 μg SFT (SFT25) allowed the strains to be placed into two groups. Strains in one group (17 strains) generated no inhibition zones and the zones obtained from the other 89 strains were distributed over a wide range but showed no natural division into separate sub-classes. A further investigation performed by one of the participating laboratories, of the susceptibility of 91 of these 106 strains used discs containing 100 μg sulfmethoxazole (SFM100) and 5 μg trimethoprim (TMP5). Application of normalised resistance interpretation to these data allowed the estimation of epidemiological cut-off values for WT strains of ≥ 9 mm for SFM100 and ≥ 21 mm for TMP5. This investigation demonstrated the presence of three distinct phenotypic classes, one containing strains manifesting wild type susceptibility to both agents, another containing strains manifesting non-wild type susceptibility to both and a third containing strains manifesting wild type susceptibility with respect to TMP but non-wild type with respect to SFM. Analysis demonstrated the inability of SFT25 discs to generate data that allowed the separate identification of strains that were fully susceptible to both TMP and SFM from those that were fully susceptible to TMP but were not fully susceptible to SFM. It is recommended that, in investigation of the susceptibility to potentiated sulphonamides of isolates from diseased fish, separate discs, containing the individual components of the mixture, should be employed.
    • Age and growth estimates for the starry smoothhound (Mustelus asterias) in the Northeast Atlantic Ocean

      Farrell, E D; Mariani, S; Clarke, M W (Oxford University Press, 2010)
      This study is the first to estimate age, growth and longevity of M. asterias based on interpretation of band pairs in sectioned vertebrae. Age and growth of 106 male and 114 female starry smooth-hound sharks (Mustelus asterias) were estimated by counting band pairs on unstained sectioned vertebrae. Growth curves were fitted to the length-at-age data using the von Bertalanffy and Gompertz models. The 1-parameter von Bertalanffy-L0 provided the best fit for males (L∞ = 104 cm TL, L0 = 30 cm TL and estimated K = 16 0.224) and females (L∞ = 133 cm TL, L0 = 30 cm TL and estimated K = 0.136). Longevity was estimated to be 11.8 and 20.2 years for males and females respectively. The length weight relationship is also presented for 304 male and 424 female M. asterias. The von Bertalanffy model was fitted to weight-at-age data. These estimates can form the basis of future work on the assessment and management of this species.
    • The Age and Growth of Pike Esox Lucius from Four Irish Trout Rivers

      Bracken, J .J. (Department of Agriculture and Fisheries [Fisheries Division], 1973)
      Age and growth of pike Esox lucius L. taken by electrical fishing in four typical Irish trout rivers were determined,using isometric axis of scales. Age data showed that young pike dominated in catches in all four rivers. Very few pike older than four years were captured. Growth of pike in these rivers was compared with earlier results obtained for lake pike. River pike were much smaller than fish of similar age from the larger limestone lakes. Tag and recapture data from the Camlin river, confirmed that mean growth results were very similar to back-calculated means per year class. Data showed little movement of pike within this system and that electrical fishing was reasonably efficient for clearance of coarse fish in shallow trout waters. Stomach contents of pike taken in Robe and Camlin rivers were qualitatively analysed.
    • The age Distribution of the Herring Stocks around the Irish Coast during 1993

      Barnwall, E.; Molloy, J. (1994)
      The age distribution of stocks is usually considered as an indication of how healthy a stock may be. In general stocks which are lightly exploited will contain a much larger proportion of older fish than a stock which is heavily exploited. A stock which is heavily exploited will probably be dependent on one year class which will recruit to the fishery and which will immediately be subjected to fishing effort. Obviously in such a fishery failure of recruitment or poor recruitment will have drastic effect on the catches. Herrings can be aged accurately until are about 10 years old and generally recruit to the adult stocks during their third year. During this year, the majority of fish will spawn for the first time.
    • Age, Growth and Diet of the brown trout Salmo Trutta L. in the Roundwood Reservoir System

      Dauod, H. A.; Bolger, T.; Bracken, J. J. (Department of Agriculture and Fisheries [Fisheries Division], 1986)
      From April to October 1983 monthly samples, totalling 343 trout, were taken from the two reservoirs at Roundwood, Co. Wicklow, using a range of gill nets. In 1984 an extensive electro-fishing programme was carried out in the Vartry River and three other feeder streams, in which 605 trout were obtained. The age data, determined from the scales, showed that there were six year classes in the South Lake and five in the North Lake. The fish from the river and feeder streams were less than 4 years old, 90% belonging to 0 + and 1 + age groups. Trout from the South Lake showed faster growth, attaining 28.7 cm at year 5, compared to 23.2 cm in the North Lake. Only six trout were over over five years old. Sexual maturity was reached during the third year. The dominant food organisms were trichopteran larvae and pupae (Limnephilus vittatus) molluscs (Potamopyrgus jenkinsi and Sphaerium corneum) and chironomid larvae (Endochironomus sp. and Tanytarsus sp.). The species composition of the fauna of both lakes was almost identical, but biomass was greater in the South Lake where the trout populations appeared to be numerically smaller. The high female to male ratios in the lakes, varying between 1.37 and 1.67 to 1 did not appear to be age related. In the Vartry River and other feeder streams the fish were young, immature and predominantly male. These fish contained many more ephemeropteran nymphs than the lake trout. The oligotrophic state of the lakes, combined with the fluctuations in water level make it unlikely that any steps can be taken to improve the sport fishery using the native trout. Development of a put and take fishery is recommended.
    • 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.
    • Ageing of Fish

      Marine Institute (Marine Institute, 2006)
      In order to assess the state of any fish stock it is vital that the age structure of that stock is known. The age profile of a stock gives an indication on how healthy the stock is. If there is a broad range of ages present, then the stock would appear to be in good shape. If there are no young fish, then recruitment (spawning) may have failed and there will be problems in the future. If there are no old fish in the stock, then there may be overfishing of the stock. Age data give a good insight into the state of the fish stock and are very important components of the information required to carry out a stock assessment.
    • American Hard-Shelled Clam Experiments in Irish Waters

      Gibson, F A; Duggan, C B (Department of Agriculture and Fisheries (Fisheries Division), 1973)
      In each of the years 1969, 1970 and 1971, the Fisheries Division of the Department of Agriculture and Fisheries, introduced experimental batches of second generation, disease free American hard-shelled clams from the hatchery operated by the Ministry of Agriculture, Fisheries and Food at Conmay North Wales to selected areas of the Irish coast. An analysis of the 1969 plantings of seed hard-shelled clam has already been made by Gibson and Duggnn in Fishery Leaflet No. 24 published in 1970. The results of further observations carried out from 1970 to 1972, are now incorporated with the 1969 data and together form the material for this Leaflet.
    • Amnesic shellfish poisoning in the king scallop, Pecten maximus, from the west coast of Scotland

      Campbell, D.A.; Kelly, M.S.; Busman, M.; Bolch, C.J.S.; Wiggins, E.; Moeller, P.D.R.; Morton, S.L.; Hess, P.; Shumway, S.E. (National Shellfisheries Association, 2001)
      The king scallop, Pecten maximus, is a valuable economic resource in the UK. The industry relies on supplying premium "roe-on" processed scallops to the continental market. In July 1999, king scallops harboring the amnesic shellfish poisoning (ASP) toxin, domnic acid (DA), in gonadal tissue at levels above the regulatory limit (20 μg DA g-1) were detected across a wide area of northern and western Scotland. In response, a survey of the southern extent of the closed harvest areas was initiated to describe variability of ASP toxin levels over varying spatial scales (<5 m to >5 km); determine the anatomical distribution of the toxin, and identify, isolate, and culture causative Pseudo-nitzschia species. Toxin analysis was conducted using a liquid chromatography-tandem mass spectroscopy (LC-MS/MS) procedure. The DA content of tissues followed the predictable rank order: all other tissue -1 gonad -1 adductor. The toxin levels within all other tissue (95% Cl = 580-760 μg DA g-1, n = 170) consistently accounted for 99% of the total individual toxin burden. DA levels in the gonad (95% CI = 8.2-11.0 μg DA g- 1, n = 170) were an order of magnitude below levels in all other tissue and contributed to less than 0.5% of the total individual toxin burden, although levels above the regulatory limit were detected in individual gonad samples. Adductor muscle tissue contained the lowest concentration of DA (95% Cl = 0.38-0.82 μg DA g- 1, n = 170), and was typically within two to three orders of magnitude below levels in all other tissue. None of the scallops examined had DA toxicities in adductor muscle tissue exceeding the regulatory limit. Toxin variability among individuals and sites was high (range of coefficients of variation (CV) in all other tissue = 29&-l20% and gonadal = 45%-85%). The results do give an indication of the scale on which microhabitat differences may influence ASP toxicity in P. maximus populations, because significant differences were found in all other and gonadal tissue toxin levels between groups of individuals only 25-m apart. In total, seven species of Pseudo-nitzschia were identified from west coast waters. A suspected causative species, P. australis, was found to produce high levels of DA, in culture. The high individual variation in toxicities and the occurrence of DA in the gonad at levels above the regula1ory limit clearly demonstrate the complexity of managing the king scallop fishery during ASP events.
    • Analysis of "Independent evaluation of Sea Trout Monitoring Programme"

      Rothschild, B. (1997)
      This report reviews the independent evaluation of the Sea Trout Monitoring Programme performed by Dr. Ian G. Cowx, University of Hull Fisheries Institute dated March 1997.
    • An Analysis of the Gravels used by Spawning Salmonids in Ireland

      Fluskey, R. D. (Department of Agriculture and Fisheries [Fisheries Division], 1989)
      Samples of gravel from 79 sites selected for spawning by Atlantic salmon, 9 selected by sea trout and 13 within spawning areas but known to be unused by spawning salmonids were analysed. For comparison reported data on 81 samples from sites used by Pacific salmon were similarly analysed. No significant difference was found between the range of gravel distributions used by salmon and that used by sea trout. It could not be proved that the sites unused by spawning fish were avoided because of excess coarseness or fineness. The range used by Pacific salmon was found to be wider than that used by Atlantic salmon. A separate analysis was made of the portion of gravel coarser than 4mm in diameter. From this a suitable mixture for use in rehabilitating disrupted spawning areas is proposed. A proposal is made that for spawning gravel analysis the 0scale where 0 = -1.log2 particle size be replaced by a 0 scale where the multiplication by -1 is omitted. Key words: Salmonids, spawning, gravel, site selection.