• Lessons for fisheries management from the EU cod recovery plan

      Kraak, Sarah B. M.; Bailey, Nick; Cardinale, Massimiliano; Darby, Chris; De Oliveira, José A. A.; Eero, Margit; Graham, Norman; Holmes, Steven; Jakobsen, Tore; Kempf, Alexander; Kirkegaard, Eskild; Powell, John; Scott, Robert D.; Simmonds, E. John; Ulrich, Clara; Vanhee, Willy; Vinther, Morten (Elsevier, 2012)
      The performance of the EU long-term management plan for cod stocks, in force since 2009, is analysed focusing on the human and institutional factors. The plan operates through landings quotas (TACs) and effort restrictions following a Harvest Control Rule, and deploys a novel instrument allowing Member States to ‘buy back’ or increase fishing effort for fleet segments engaged in cod-avoidance measures. The stipulated fishing mortality reductions have not been achieved. On the positive side, the ‘buy-back’ instrument has led to increased uptake of selective gear and implementation of permanent and real-time temporary closures. On the negative side, ignoring the dimension of fishers as reactive agents in the design, the impact assessment, and the annual implementation of the measures has contributed to the failure to adequately implement the plan and achieve its objectives. The main problem is that the landings quotas taken in a mixed fishery did not limit catches because fishers were incentivised to continue fishing and discard overquota catch while quota for other species was available. The effort limitations intended to reduce this effect were insufficient to adequately limit fishing mortality in targeted fisheries, although fishers experienced them as prohibiting the full uptake of other quotas. Recommendations for future plans include (i) management through catch rather than landings quotas, (ii) the internalisation of the costs of exceeding quotas, (iii) use of more selective gear types, (iv) the development of appropriate metrics as a basis for regulatory measures and for evaluations, (v) participatory governance, (vi) fishery-based management, (vii) flexibility in fishing strategy at vessel level.
    • ‘Linking Herring’: do we really understand plasticity?

      Dickey‐Collas, M; Clarke, M; Slotte, A (Oxford University Press, 2009)
      The symposium was organized to link our understanding of herring biology, population dynamics, and exploitation in the context of ecosystem complexity. It is beyond argument that herring play a pivotal role in shaping the structure and dynamics of many boreal continental-shelf ecosystems. Therefore, in moving to an ecosystem approach to fishery management, the time seemed right for ICES to hold another herring symposium. Since the last ICES symposia on herring in the 1960s (“Herring Symposium”, 1961; “Biology of Early Stages and Recruitment Mechanisms of Herring”, 1968), many of the old paradigms have been rejected, and substantial progress has been made by striking out along new avenues. In addressing this particular topic, we were also able to follow on from the decadal herring symposia series held in North America, and thus cover new research from both the ICES and PICES communities. The symposium took place from 26 to 29 August 2008, at the National University of Ireland, Galway, Ireland.
    • A Low-Complexity Mosaicing Algorithm for Stock Assessment of Seabed-Burrowing Species

      Corrigan, D.; Sooknanan, K.; Doyle, J.; Lordan, C.; Kokaram, A. (IEEE Xplore, 2018)
      This paper proposes an algorithm for mosaicing videos generated during stock assessment of seabed-burrowing species. In these surveys, video transects of the seabed are captured and the population is estimated by counting the number of burrows in the video. The mosaicing algorithm is designed to process a large amount of video data and summarize the relevant features for the survey in a single image. Hence, the algorithm is designed to be computationally inexpensive while maintaining a high degree of robustness. We adopt a registration algorithm that employs a simple translational motion model and generates a mapping to the mosaic coordinate system using a concatenation of frame-by-frame homographies. A temporal smoothness prior is used in a maximum a posteriori homography estimation algorithm to reduce noise in the motion parameters in images with small amounts of texture detail. A multiband blending scheme renders the mosaic and is optimized for the application requirements. Tests on a large data set show that the algorithm is robust enough to allow the use of mosaics as a medium for burrow counting. This will increase the verifiability of the stock assessments as well as generate a ground truth data set for the learning of an automated burrow counting algorithm.
    • Managing a complex population structure: exploring the importance of information from fisheries-independent sources

      Hintzen, N.T.; Roel, B.; Benden, D.; Clarke, M.; Egan, A.; Nash, R.D.M.; Rohlf, N.; Hatfield, E.M.C. (Oxford University Press, 2014)
      Natural resource managers aim to manage fish stocks at sustainable levels. Often, management of these stocks is based on the results of analytical stock assessments. Accurate catch data, which can be attributed to a specific population unit and reflects the population structure, are needed for these approaches. Often though, the quality of the catch data is compromised when dealing with a complex population structure where fish of different population units mix in a fishery. The herring population units west of the British Isles are prone to mixing. Here, the inability to perfectly allocate the fish caught to the population unit they originate from, due to classification problems, poses problems for management. These mixing proportions are often unknown; therefore, we use simulation modelling combined with management strategy evaluation to evaluate the role fisheries-independent surveys can play in an assessment to provide unbiased results, irrespective of population unit mixing and classification success. We show that failure to account for mixing is one of the major drivers of biased estimates of population abundance, affecting biomass reference points and MSY targets. When mixing of population units occurs, the role a survey can play to provide unbiased assessment results is limited. Either different assessment models should be employed or stock status should be considered from the survey data alone. In addition, correctly classifying the origin of fish is especially important for those population units that are markedly smaller in size than other units in the population complex. Without high classification success rates, smaller population units are extremely vulnerable to overexploitation.
    • Migration and Fisheries of North East Atlantic Mackerel (Scomber scombrus) in Autumn and Winter

      Jansen, Teunis; Campbell, Andrew; Kelly, Ciarán; Hátún, Hjálmar; Payne, Mark R. (Public Library of Science (PLOS), 2012)
      It has been suggested that observed spatial variation in mackerel fisheries, extending over several hundreds of kilometers, is reflective of climate-driven changes in mackerel migration patterns. Previous studies have been unable to clearly demonstrate this link. In this paper we demonstrate correlation between temperature and mackerel migration/distribution as proxied by mackerel catch data from both scientific bottom trawl surveys and commercial fisheries. We show that mackerel aggregate and migrate distances of up to 500 km along the continental shelf edge from mid-November to early March. The path of this migration coincides with the location of the relatively warm shelf edge current and, as a consequence of this affinity, mackerel are guided towards the main spawning area in the south. Using a simulated time series of temperature of the shelf edge current we show that variations in the timing of the migration are significantly correlated to temperature fluctuations within the current. The proposed proxies for mackerel distribution were found to be significantly correlated. However, the correlations were weak and only significant during periods without substantial legislative or technical developments. Substantial caution should therefore be exercised when using such data as proxies for mackerel distribution. Our results include a new temperature record for the shelf edge current obtained by embedding the available hydrographic observations within a statistical model needed to understand the migration through large parts of the life of adult mackerel and for the management of this major international fishery.
    • Mismatch between fish landings and market trends: a western European case study

      Miller, Dana; Clarke, Maurice; Mariani, Stefano (Elsevier, 2012)
      As an island nation, Ireland is connected to and responsible for the seas that surround it. Fishing has historically been one of the major anthropogenic activities linking Irish society to the marine environment. Deriving an approach from historical ecology, we investigated temporal patterns in the diversity of seafood landed, traded and marketed in Ireland by collating long-term datasets acquired from government sources and through conducting contemporary product surveys. Our findings suggest that consumer preferences have not adapted to changes in local resource supply. From the beginning of the 20th century, Irish landings of some of the traditionally most important seafood products have gradually grown, then sharply declined within the most recent 10-20 years, but access to ample supply appears to have been maintained in the Irish marketplace. Our results indicate that this trend has been concealed from consumers through import, aquaculture production and mislabeling. Future intentions of responsible management must incorporate policy implementation and enforcement, consumer education and industry transparency.
    • A Model Compound Study: The ecotoxicological evaluation of five organic contaminants with a battery of marine bioassays

      Macken, A; Giltrap, M; Foley, B; McGovern, E; McHugh, B; Davoren, M (Elsevier, 2008)
      This paper describes the ecotoxicological evaluation of five organic contaminants frequently detected in marine sediments (tributyltin, triphenyltin, benzo[a]pyrene, fluoranthene, and PCB 153) using three marine species (Vibrio fischeri, Tetraselmis suecica, and Tisbe battagliai). The sensitivity of each species varied for all compounds. The triorganotins were consistently the most toxic to all species. The applicability of each test system to assess the acute toxicity of environmental contaminants and their use in Toxicity Identification Evaluation (TIE) is discussed. Suitability of the Microtox and T. battagliai tests for employment in TIE studies were further assessed through spiking experiments with tributyltin. Results demonstrated that the most effective treatment to remove organotin toxicity from the sample was the C18 resin. The results of this study have important implications for risk assessment in estuarine and coastal waters in Ireland, where, at present the monitoring of sediment and water quality is predominantly reliant on chemical analysis alone. Ecotoxicological evaluation of five organic marine sediment contaminants was conducted and the suitability of the test species for marine porewater TIE discussed.
    • Modelling sympatric speciation by means of biologically plausible mechanistic processes as exemplified by threespine stickleback species pairs

      Kraak, Sarah Belle Mathilde; Hart, Paul J. B. (Springer, 2011)
      We investigate the plausibility of sympatric speciation through a modelling study. We built up a series of models with increasing complexity while focussing on questioning the realism of model assumptions by checking them critically against a particular biological system, namely the sympatric benthic and limnetic species of threespine stickleback in British Columbia, Canada. These are morphologically adapted to their feeding habits: each performs better in its respective habitat than do hybrids with intermediate morphology. Ecological character displacement through disruptive selection and competition, and reinforcement through mating preferences may have caused their divergence. Our model assumptions include continuous morphological trait(s) instead of a dimorphic trait, and mating preferences based on the same trait(s) as selected for in food competition. Initially, morphology is intermediate. We apply disruptive selection against intermediates, frequency-dependent resource competition, and one of two alternative mating preference mechanisms. Firstly, preference is based on similarity where mating preference may result from “imprinting” on conspecifics encountered in their preferred foraging habitat. Here, speciation occurs easily—ecological hybrid inferiority is not necessary. Hybrid inferiority reinforces the stringency of assortative mating. Secondly, individual preferences exist for different trait values. Here, speciation occurs when linkage disequilibrium between trait and preference develops, and some hybrid inferiority is required. Finally, if the morphology subject to disruptive selection, frequency-dependent competition, and mate choice, is coded for by two loci, linkage disequilibrium between the two loci is required for speciation. Speciation and reinforcement of stringency of choosiness are possible in this case too, but rarely. Results demonstrate the contingency of speciation, with the same starting point not necessarily producing the same outcome. The study resulted in flagging issues where models often lack in biological realism and issues where more empirical studies could inform on whether assumptions are likely valid.
    • A multi-proxy palaeolimnological study to reconstruct the evolution of a coastal brackish lake (Lough Furnace, Ireland) during the late Holocene

      Cassina, Filippo; Dalton, Catherine; Dillane, Mary; De Eyto, Elvira; Poole, Russell; Sparber, Karin (Elsevier, 2013)
      This study examines the evolution of Lough Furnace, a coastal brackish lake in the west of Ireland, using high-resolution sensors in the water column and palaeolimnological examination of the sediment archive. Palaeoenvironmental reconstructions suggest that meromixis formed as a result of sea level rise prior to ca. 4000 cal. yr BP. Increased seawater inflow has progressively led to permanent water stratification, which caused the onset of anoxia, making the monimolimnion a harsh environment for biological life. Diatom floristic interpretations suggest a progressive upcore increase in salinity, which is paralleled by a reduction in cladocera remains. Diagenetic processes have not altered the sediment organic matter signature. Organic matter mainly derives from freshwater DOC and appears to be linked to the presence of peat bogs in the catchment as confirmed by the C/N ratio. Upcore variations in the C/N ratio with a ca. 800-year periodicity have been interpreted as the result of alternating dry and wet climatic phases during the late Holocene, which appear synchronous with the NAO and long-term solar cycles. The current hydrology is largely controlled by freshwater inflow, which determines permanent meromictic conditions. Overturns are rare, requiring a specific combination of factors such as exceptionally dry and warm summers followed by cool autumns. According to the climate projections for the next century in Ireland, permanent meromictic conditions will probably continue.
    • A mussel tissue certified reference material for multiple phycotoxins. Part 1: design and preparation

      McCarron, P; Emteborg, H; Nulty, C; Rundberget, T; Loader, J I; Teipel, K; Miles, C O; Quilliam, M A; Hess, P (Springer Berlin / Heidelberg, 2011)
      The development of multi-analyte methods for lipophilic shellfish toxins based on liquid chromatography–mass spectrometry permits rapid screening and analysis of samples for a wide variety of toxins in a single run. To ensure accuracy of results, validated methods and appropriate certified reference materials (CRMs) are required. CRMs are essential for accurate instrument calibration, for assessing the complete analytical method from sample extraction to data analysis, and for verifying trueness. However, CRMs have hitherto only been available for single toxin groups. Production of a CRM containing six major toxin groups was achieved through an international collaboration. Preparation of this material, CRM-FDMT1, drew on information from earlier studies as well as improved methods for handling bulk tissues, production of reference materials, and isolation of toxins. Previous investigations of stabilisation techniques indicated freeze-drying to be a suitable procedure for preparation of shellfish toxin RMs and applicable to a wide range of toxins. CRM-FDMT1 was initially prepared as a bulk wet tissue homogenate with planned concentrations of domoic acid, okadaic acid, dinophysistoxins, azaspiracids, pectenotoxins, yessotoxin and spirolides. The homogenate was then freeze dried, milled and bottled in aliquots suitable for distribution and analysis. The moisture content and particle size distribution were measured, and determined to be appropriate. A preliminary toxin analysis of the final material showed a comprehensive toxin profile.
    • Natural selection acts on Atlantic salmon major histocompatibility (MH) variability in the wild

      de Eyto, E.; McGinnity, P.; Consuegra, S.; Coughlan, J.; Tufto, J.; Farrell, K.; Megens, H.J.; Jordan, W.; Cross, T.; Stet, R.J.M. (Royal Society Publishing, 2007)
      Pathogen-driven balancing selection is thought to maintain polymorphism in major histocompatibility (MH) genes. However, there have been few empirical demonstrations of selection acting on MH loci in natural populations. To determine whether natural selection on MH genes has fitness consequences for wild Atlantic salmon in natural conditions, we compared observed genotype frequencies of Atlantic salmon (Salmo salar) surviving in a river six months after their introduction as eggs with frequencies expected from parental crosses. We found significant differences between expected and observed genotype frequencies at the MH class II alpha locus, but not at a MH class I-linked microsatellite or at seven non-MH-linked microsatellite loci. We therefore conclude that selection at the MH class II alpha locus was a result of disease-mediated natural selection, rather than any demographic event. We also show that survival was associated with additive allelic effects at the MH class II alpha locus. Our results have implications for both the conservation of wild salmon stocks and the management of disease in hatchery fish. We conclude that natural or hatchery populations have the best chance of dealing with episodic and variable disease challenges if MH genetic variation is preserved both within and among populations.
    • Numerical modelling of spatio-temporal variability of growth of Mytilus edulis (L.) and influence of its cultivation on ecosystem functioning

      Dabrowski, T.; Lyons, K.; Curé, M.; Berry, A.; Nolan, G. (Elsevier, 2013)
      One of the key needs of the aquaculture industry is the implementation of effective management methods to ensure the sustainability, economic viability and minimization of negative impacts on both human and ecosystem well-being. The authors developed a Fortran 90 implementation of the dynamic energy budget (DEB) model for Mytilus edulis. The model has been further developed to include physiological interactions with the ecosystem and coupled to a biogeochemical nutrient–phytoplankton–zooplankton–detritus (NPZD) model. Phytoplankton and detritus uptakes, oxygen utilisation, CO2 production, NH4 excretion, egestion of faeces, and assimilation of food are modelled. A novel approach was derived that accounts for the allocation of C and N in mussel flesh and shell organic fraction. The DEB–NPZD model has been subsequently coupled to a high resolution three dimensional numerical coastal ocean model of the south–west coast of Ireland, where approximately 80% of national rope mussel is produced annually. Simulations have been carried out for the time period July 2010–June 2011, for which the field data on mussel biometrics and ambient seawater properties were collated. The model accurately reproduced the spatio-temporal variability in blue mussel growth. It is also shown that the ecosystem dynamics is affected by the presence of aquaculture farms. The modelling system presented allows for the assessment of the impacts of aquaculture activities on water quality, quantification of the production and ecological carrying capacities and improvement of our understanding of the ecosystem functioning with particular emphasis on interactions between various trophic levels.
    • The occurrence of persistent chlorinated and brominated organic contaminants in the European eel (Anguilla anguilla) in Irish waters

      McHugh, B; Poole, R; Corcoran, J; Pinelopi, A; Boyle, B (Elsevier, 2010)
      The European eel (Anguilla anguilla) is a relatively high lipid, long lived species capable of living in a variety of brackish, fresh and marine habitats. As such, eels can accumulate organic pollutants and have been incorporated into environmental monitoring programs as a suitable “bioindicator” species for the determination of the levels of organic contaminants within different water bodies. The global eel stock is now in decline and while the cause of the collapse remains unidentified, it is likely to include a combination of anthropogenic mortality in addition to environmental degradation. This study provides valuable data on a range of contaminants (PCDD/Fs, PCBs, OCPs, PBDEs, HBCD, TBBPA and PBBs) and extractable lipid levels in eel muscle tissue collected from five Irish catchments. Extractable lipid levels were lower in the yellow eels compared to those in the silver eels. These levels were similar to those reported elsewhere and it has been posited that a decline in the lipid content in yellow eels may have consequences for the future viability of the stock. With the exception of higher substituted dioxins (especially OCDD), in three samples collected from one catchment (Burrishoole) in the West of Ireland, POP levels in general were determined to be low in eels from Irish waters compared to those in other countries.
    • The occurrence of persistent chlorinated and brominated organic contaminants in the European eel (Anguilla anguilla) in Irish waters

      McHugh, B; Poole, R; Corcoran, J; Anninou, P; Boyle, B; Joyce, E; Foley, M B; McGovern, E (Elsevier, 2010)
      The European eel (Anguilla anguilla) is a relatively high lipid, long lived species capable of living in a variety of brackish, fresh and marine habitats. As such, eels can accumulate organic pollutants and have been incorporated into environmental monitoring programs as a suitable “bioindicator” species for the determination of the levels of organic contaminants within different water bodies. The global eel stock is now in decline and while the cause of the collapse remains unidentified, it is likely to include a combination of anthropogenic mortality in addition to environmental degradation. This study provides valuable data on a range of contaminants (PCDD/Fs, PCBs, OCPs, PBDEs, HBCD, TBBPA and PBBs) and extractable lipid levels in eel muscle tissue collected from five Irish catchments. Extractable lipid levels were lower in the yellow eels compared to those in the silver eels. These levels were similar to those reported elsewhere and it has been posited that a decline in the lipid content in yellow eels may have consequences for the future viability of the stock. With the exception of higher substituted dioxins (especially OCDD), in 3 samples collected from one catchment (Burrishoole) in the West of Ireland, POP levels in general were determined to be low in eels from Irish waters compared to those in other countries.
    • The oil spill model OILTRANS and its application to the Celtic Sea

      Berry, Alan; Dabrowski, Tomasz; Lyons, Kieran (Elsevier, 2012)
      This paper describes details of an oil spill model, OILTRANS, developed by the authors. The model is an off-line particle-transport model coupled to the most up to date operational met-ocean model forecasts. Formulations for the dominant oil fate processes of spreading, advection, diffusion, evaporation, emulsification and dispersion have been encoded, providing the model with the ability to accurately predict the horizontal movement of surface oil slick, the vertical entrainment of oil into the water column and the mass balance of spilled oil. The application of the OILTRANS model to an accidental release during a ship-to-ship fuel transfer in the Celtic Sea in February 2009 is presented to validate the system. Comparisons with aerial observations of the oil slick at the time of the incident, and subsequent model simulations, indicate that the OILTRANS model is capable of accurately predicting the transport and fate of the oil slick.
    • An operational biogeochemical model of the North-East Atlantic: model description and skill assessment

      Dabrowski, T.; Lyons, K.; Berry, A.; Cusack, C.; Nolan, G. (Elsevier, 2013)
      This paper presents a high resolution operational biogeochemical model of the North-East Atlantic that encompasses part of the continental shelf and adjacent deep sea and includes all of Ireland's territorial waters. The setup of the model is described, followed by its skill assessment in reproducing chlorophyll and nitrate spatio-temporal variability. Part of the model skill assessment concerns the evaluation of its usefulness in a decision-making process and is based on the application of a binary discrimination analysis. The model is one-way nested within a 1/12° Mercator Ocean PSY2V4R2 operational model that provides physical forcing at the lateral open boundaries. Nitrate fields are also proscribed at the open boundaries; the World Ocean Atlas 2009 monthly climatologies are used in the upper 500 m and at greater depths a formula that relates nitrate concentration to temperature and latitude is applied in the model. The model represents the intra-annual variability of surface chlorophyll and nitrate concentrations at monthly time scales across key oceanographic regions reasonably well; deficiencies are identified in some regions along with possible causes. The model can reproduce important characteristic bio-physicochemical features e.g. the frontal dynamics and upwelling off southwest Ireland and the properties of different water masses in the Rockall Trough. The model is deemed suitable for operational purposes, with a high probability to make correct positive and negative decisions. Operational since 2011, the output is publicly available via a dedicated THREDDS server.
    • Overcoming the “tragedy of the commons” in fishery management

      Kraak, S. B. M. (International Council for the Exploration of the Sea (ICES), 2011)
      In situations of declining or depleted fish stocks, fishers seem to have fallen prey to the “tragedy of the commons”. This occurs because fishers face the dilemma that, although they understand that limiting their catches would pay off in the form of sustainable future catches, they can never be sure that the catch which they have just sacrificed will not be immediately snapped up by competing fishers. Standard economic theory predicts that, in such dilemmas, individuals are not willing to cooperate and sacrifice catches in the short term, and that, consequently, the resource is overharvested. However, over past decades, a multitude of research endeavours have shown that humans often achieve outcomes that are “better than rational” by building conditions where reciprocity, reputation, and trust help to overcome the temptations of short-term self-interest.
    • Phosphorus release from forest harvesting on an upland blanket peat catchment

      Rodgers, Michael; O’Connor, Mark; Healy, Mark Gerard; O’Driscoll, Connie; Asam, Zaki-ul-Zaman; Nieminen, Mika; Poole, Russell; Müller, Markus; Xiao, Liwen (Elsevier, 2010)
      The aim of this study was to investigate the release of phosphorus (P) to receiving waters resulting from harvesting 34-year-old lodgepole pine trees in an upland peat catchment. The study site was within a 25.3-hectare (ha) area, and was drained by a stream that received flows from ploughed furrows, mainly, via collector drains, and discharged directly to the salmonid Shrahrevagh River, Burrishoole, Co. Mayo, Ireland. The study site was divided in two parts: the upstream part was left intact and the downstream part was harvested in early Autumn 2005 following implementation of forest guidelines. Good management practices such as proper use of brash mats and harvesting only in dry weather were implemented. Two instrumented stations were established – one just upstream (US) and the other just downstream (DS) of the clearfelled area. The measurement of P concentrations at the two stations commenced in May 2005, two months before the harvesting started. The daily mean P concentration at the DS station increased from about 6 μg L-1 of total reactive phosphorus (TRP) during pre-clearfelling to 429μg L-1 in August 2006. By October 2009, four years after clearfelling, the P concentrations at the DS station had returned to pre-clearfelling levels. In the first three years after harvesting, up to 5.15 kg ha-1 of TRP were released from the harvested catchment to the receiving water; in the second year alone, 2.3 kg ha-1 of TRP were released. Linear regression can be used to describe the relationship between TRP load and water discharge. About 80 % of the total phosphorus (TP) in the study stream was soluble and more than 70 % of the P release occurred in storm events, indicating that traditional buffer strips with widths of 15-20 m might not be efficient for P immobilization. The P concentrations were affected by antecedent weather conditions and highest concentrations occurred during storm events following prolonged drought periods. The water extractable phosphorus (WEP) contents in the soil were significantly higher below windrow/brash material than in brash-free areas, and whole-tree harvesting should be studied as one of the means to decrease P export from blanket peats.
    • Population specific smolt development, migration and maturity schedules in Atlantic salmon in a natural river environment

      McGinnity, P; deEyto, E; Cross, T F; Coughlan, J; Whelan, K; Ferguson, A (Elsevier, 2007)
      Identifying differences in quantitative life history traits between cultured and native or non-native wild populations is important in assessing the impact of accidental and deliberate introductions of hatchery-reared fish into the wild. As the ability to exploit the marine environment is the defining life history characteristic of anadromous salmonids, knowledge of variation in smoltification characteristics among populations is crucial in determining how these introductions affect fitness in recipient populations. Data are presented here describing the timing and extent of the autumn migration; the propensity for male parr maturation; the timing of the spring migration; and the size of autumn and spring migrants from Atlantic salmon (Salmo salar) populations from various genetic backgrounds. These experiments were carried out under common garden conditions over a decade in the Srahrevagh River in the west of Ireland. Population specific genetically determined differences in quantitative life history traits associated with smoltification were apparent. These differences may reflect smolt quality and therefore impact on marine survival and ultimately lifetime fitness. Both hatchery domestication and geography (different selective environments) were found to be important factors determining smolt phenotypes, although it was difficult to measure the relative contribution of each. These results indicate that farm, native hatchery, non-native wild salmon (even from a neighbouring catchment) and their hybrids with native wild fish, are likely to produce less well adapted and thus poorer quality smolts than native wild populations and, where wild populations are extant, such stocks should not be used for enhancement purposes.
    • A potential solution to mitigate phosphorus release following clearfelling in peatland forest catchments

      O’Driscoll, Connie; Rodgers, Michael; O’Connor, Mark; Asam, Zaki-ul-Zaman; de Eyto, Elvira; Poole, Russell; Xiao, Liwen (Springer, 2011)
      Since the 1950s, large areas of upland peat have been afforested in northern European countries. Due to the poor phosphorus (P) adsorption capacity and low hydraulic permeability in blanket peat soil and increased labile P sources, harvesting these blanket peat forests can significantly increase P concentrations in the receiving aquatic systems. This paper briefly reviews the current management practices on the control of P releases from forestry in Ireland and the UK, and proposes a possible novel practice—grass seeding clearfelled areas immediately after harvesting, which should reduce P release from blanket peat forest harvesting. The study was conducted in the Burrishoole Catchment in the west of Ireland. A field trial was carried out to identify the successful native grass species that could grow quickly in the blanket peat forest. The two successful grass species—Holcus lanatus and Agrostis capillaris—were sown in three blanket peat forest study plots with areas of 100, 360, and 660 m2 immediately after harvesting. Areas without grass seeding were used as controls. One year later, the P content in the aboveground vegetation biomass of the three study plots were 2.83, 0.65, and 3.07 kg P ha−1, respectively, which were significantly higher than the value of 0.02 kg P ha−1 in the control areas. The water extractable phosphorus in the three study plots were 8.44, 9.83, and 6.04 mg (kg dry soil)−1, respectively, which were lower than the value of 25.72 mg (kg dry soil)−1 in the control sites. The results indicate that grass seeding of the peatland immediately after harvesting can quickly immobilize significant amounts of P and warrants additional research as a new Best Management Practice following harvesting in the blanket peatland forest to mitigate P release.