Marine Institute Open Access Repository

Welcome to the Marine Institute Open Access Repository

The Marine Institute Open Access Repository facilitates full text access to the publications of the Marine Institute in accordance with copyright permissions. The aim of the Repository is to collect, preserve and provide open access to the publications of the Marine Institute, including the research publications supported by National and European funded marine research programmes.

Featured Items

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The Stock Book 2025: Annual Review of Fish Stocks in 2025 with Management Advice for 2026

Marine Institute

The Stock Book is the principal annual publication of the Marine Institute's Fisheries Ecosystems Advisory Services (FEAS). Its purpose is to provide the latest impartial scientific advice on the commercially exploited fish stocks of interest to Ireland. The Stock Book is used by the Department of Agriculture, Food and the Marine - (DAFM) at the Total Allowable Catch (TAC) negotiations with the EU in December and throughout the year at fisheries management meetings.

2025-12

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Annual Report 2024/Tuarascáil Bhliantúil 2024 (English and Irish/Bilingual versions)

Marine Institute

The Marine Institute is the national agency for marine research, technology, development and innovation. It seeks to assess and realise the economic potential of Ireland’s marine resource, promote sustainable development of marine industry through strategic funding programmes and essential scientific services, as well as safeguard Ireland’s natural marine resource through research and environmental monitoring. Ireland has a marine area of approximately 880,000 km2 under the sea, which is over 10 times its land area, representing an enormous seabed and marine resource. The Marine Institute promotes the sustainable development of this vast resource through research, the application of new technologies and by providing credible science-based advice to industry, the Government and the EU.

2025

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Ireland’s Ocean Economy, 2025

Flynn, Niall; Frost, Deirdre; O'Leary, Jenny; Mehorta, Sanjana; Tran, Tuyen; Hynes, Stephen

Ireland’s Ocean Economy Report, 2025, provides an update on Ireland’s ocean economy across three main economic indicators: turnover, gross value added (GVA) and employment. It provides an analysis of trends over a five-year period and a commentary on rates of change over a ten-year timeframe. The report is accompanied by an online dashboard, where data trends can be accessed. The 2025 Ocean Economy Report is the ninth in the ocean economy series. Ireland’s ocean economy statistics are based on nominal values.

2025-12

Recent Submissions

  • PublicationOpen Access
    Environmental Survey of Coastal Waters (Galway - Dublin – Galway): Winter nutrients, benthic macro-invertebrate and contaminants monitoring (TC24002)
    (Marine Institute, 2024-03) O Donnell, Garvan; Healy, Louise
    The 2024 survey was designed to collect multidisciplinary information on physical conditions, water chemistry (dissolved oxygen, dissolved nutrients, total alkalinity (TA), dissolved inorganic carbon (DIC) and salinity), sediment chemistry (persistent organic pollutants POPs and trace metals), sediment particle size distribution and benthic macroinvertebrates (at targeted waterbodies around the coast). This contributes to data collection needs of various statutory drivers (WFD and the Marine Strategy Framework Directive (MSFD) Directive 2008/56/EC) as well as providing a research dataset on status and changing conditions (trends and variations) for key environmental variables. The 2024 survey was south-about departing Galway, initially travelling north and eventually finishing in Cork.
  • PublicationOpen Access
    Winter Environmental Survey 2013 (Dublin – Galway): Winter nutrients, carbonate chemistry parameters, benthic macro-invertebrates and contaminants monitoring (CV13-001)
    (Marine Institute, 2013) Marine Institute
    The 2013 survey was designed to collect multidisciplinary information on physics, water chemistry (dissolved nutrients, dissolved oxygen, carbonate parameters (TA, DIC), salinity), sediment chemistry (persistent organic pollutants POPs and trace metals) sediment particle size distribution and benthic macroinvertebrates. This contributes to data collection needs of various statutory drivers (WFD Dir 2000/60/EC) as well as providing a research dataset on status and changing conditions (trends and variations) for key environmental variables. Previous winter nutrient surveys for the Irish Sea in the 1990s were extended into the Celtic Sea and coastal waters of the west coast in recent years. The current annual surveys alternately survey northabout and southabout (2011 & 2013 southabout, 2012 and 2014 Northabout) thus providing a complete coverage of Irelands coastal waters over 2 year periods
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    Multi-Seasonal eDNA Metabarcoding Highlights a Resurgence in Fish Diversity Across a Severely Impacted Estuarine Ecosystem
    (Wiley, 2026-02-27) Jackman, Jake; Guimaraes Sales, Naiara; Benvenuto, Chiara; Drewitt, Andrea; Wolfeden, Andrew; Robins, Peter; Coscia, Ilaria; McDevitt, Allan
    Aquatic ecosystems have been in an alarming state of decline for decades. In particular, estuarine ecosystems have experienced long-term declines in fish diversity due to factors such as habitat degradation, pollution and altered hydrology. Monitoring these systems is often limited by the difficulty and cost of conventional survey methods. In this study, we applied environmental DNA (eDNA) metabarcoding to assess fish diversity in the Mersey Estuary (UK), a historically severely impacted system. Monthly water samples were collected over a year (2023–2024) across saline, brackish, and freshwater zones. Overall, 69 species were detected, surpassing both historical (46 species) and recent (39 species) records. Richness was highest in the upper freshwater zones, and several species were recorded returning to the estuary for the first time since pre-industrial times (∼1850s). Peak species richness occurred during winter (December–February). Species composition varied monthly and spatially, though not consistently by season. Approximately 15% of detected species were diadromous, with the endangered Atlantic salmon (Salmo salar) being frequently detected during its key spawning period (October–December), for example. The results presented here indicate a resurgence in estuarine fish diversity in the Mersey and highlight eDNA metabarcoding as a rapid, sensitive tool for monitoring both contemporary and historically absent species, supporting conservation and restoration efforts.
  • ItemOpen Access
    Celtic Sea Herring Acoustic Survey Report 2025 (C-PAS), 09 - 29 October 2025
    (Marine Institute, 2025-12) O'Donnell, Ciaran; Mullins, Eugene; Daly, Eoghan
    The 2025 Celtic Sea Herring Acoustic Survey (C‑PAS; TC25021) was conducted aboard the RV Tom Crean from 9–29 October 2025 to assess the relative abundance and biomass of small pelagic fish species, including herring, sprat, and sardine, in the Celtic Sea and southern Irish Sea. The survey used systematic acoustic transects supported by targeted trawl sampling, with acoustic data collected primarily during daylight hours to align with co‑occurring regional surveys and species behaviour. Biological sampling provided information on species composition and population structure, with additional herring tissue samples collected for stock‑origin studies. Hydrographic conditions were measured using CTD casts, and zooplankton samples were collected for image‑based analysis. Apex predator surveys were conducted for seabirds throughout the survey and for marine mammals during leg two. Celtic Sea herring biomass was estimated at 1,962 t (14.895 million individuals; CV 0.66), composed predominantly of mature fish and observed mainly offshore. Sprat biomass was estimated at 9,085 t (2,946.6 million individuals; CV 0.24), while sardine biomass was 15,374 t (720.7 million individuals; CV 0.51). No anchovy estimate was produced. Results indicate that the mature component of the Celtic Sea herring stock remains low, with no clear evidence of improved recruitment.
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    Western European Shelf Pelagic Acoustic Survey (WESPAS) Survey Report 2025
    (Marine Institute, 2025-11) O'Donnell, Ciaran; O'Malley, Michael; Mullins, Eugene; Daly, Eoghan; De Loose , Emilie
    The 2025 Western European Shelf Pelagic Acoustic Survey (WESPAS; CE25009) was conducted aboard the RV Celtic Explorer from 18 June to 29 July 2025 to assess the abundance, biomass, and distribution of key small pelagic fish species, including boarfish, western horse mackerel, and herring, across shelf seas from northern Biscay to the Hebrides. The fisheries‑independent trawl‑acoustic survey covered 60,374 nmi² between 47°30′N and 58°30′N using systematic parallel transects, with effort and timing comparable to 2024. Targeted midwater trawls were undertaken on insonified echotraces to determine species composition and biological characteristics, including length, weight, sex, maturity, and age. Genetic tissue sampling, hydrographic profiling, zooplankton sampling, and marine mammal observations were also conducted. The survey provides a snapshot index of relative abundance and biomass at the time of sampling. Malin Shelf herring total stock biomass (TSB) was estimated at 56,078 t, with spawning stock biomass (SSB) of 7,142 t, representing an 89% decline in SSB compared to 2024 and the lowest value in the time series. Boarfish TSB and abundance declined by 36% and 44%, respectively, to 279,376 t and 6.67 billion individuals. In contrast, horse mackerel TSB increased by 29% to 96,204 t. Celtic Sea herring were not observed and are excluded from stock assessment inputs.
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