New research reveals new information about sea trout in Irish Sea set to inform conservation management

Inland Fisheries Ireland launches Celtic Sea Trout Project Report following Irish-Welsh Collaboration

Friday, 27th of January 2017: Inland Fisheries Ireland has published a new report called The Celtic Sea Trout Project (CSTP) which addresses significant knowledge gaps around sea trout. This migratory trout has a significant fisheries value however some sea trout fisheries in parts of Ireland and the UK bordering the Irish Sea are suffering decline.

The project, which consisted of a multi-agency partnership investigation into sea trout stocks and fisheries of rivers entering the Irish Sea, aimed to address the knowledge gaps, and identify the causes of decline with a view to supporting potential management solutions. Current understanding suggests that the incidence of sea trout and the composition and status of their stocks is sensitive to changes in the environments in which they live. These life history features and the sea trout’s widespread occurrence, make it a unique and potentially sensitive indicator of environmental change.

The structure of the Irish Sea and the variety of rivers draining to it, ranging from the mountainous rivers of West Wales to the lowland rivers of East Ireland, meant there was a wide range of marine and freshwater environments for the study. Funded under the INTERREG IVA Ireland Wales Programme, the Celtic Sea Trout Project was the first project in Ireland and the UK to combine a variety of disciplines in the study of sea trout and their fisheries on a large scale.

Dr Willie Roche, Senior Research Officer, Minister Sean Kyne T.D. and Dr Cathal Gallagher, Head of Research at Inland Fisheries Ireland at the launch of the Celtic Sea Trout Project
Dr Willie Roche, Senior Research Officer, Minister Sean Kyne T.D. and Dr Cathal Gallagher, Head of Research at Inland Fisheries Ireland
at the launch of the Celtic Sea Trout Project


Sean Kyne TD, Minister with responsibility for Inland Fisheries said, “I particularly welcome this report and the exemplary collaboration between Irish researchers at Inland Fisheries Ireland and other bodies and their international counterparts.  The research has resulted in a better understanding of the Sea Trout stocks in the Irish and Celtic seas and this will underpin logical and well-informed decisions on the management requirements that are needed to safeguard these stocks into the future and to ensure the maximum social and economic contribution is secured”.

Dr Cathal Gallagher, Head of Research at Inland Fisheries Ireland said: “This is a ground-breaking multi-agency partnership investigation which aims to fill some of the information gaps around sea trout conservation. The first study of its kind, the Celtic Sea Trout Project is a wide-scale comprehensive, cross-disciplinary project which has provided valuable insight into many important research needs in this area, which were first identified at the International Symposium on Sea Trout in 2004. Its primary purpose of improving understanding of sea trout stocks in order to support better management in the freshwater and marine environments has been achieved.”

The research will improve the management and long term future of sea trout in the Irish Sea by providing information and advice for management which can be translated into fishery and conservation benefits for countries bordering the Irish Sea. It has also established a wider awareness and long term network of people working to secure the future of sea trout.

Partners in the Celtic Sea Trout Project included: Inland Fisheries Ireland, Bangor University, University College Cork, Natural Resources Wales, the Environment Agency (England), Isle of Man Government, Nith District Salmon Fisheries Board, Galloway Fisheries Trust, Annan District Salmon Fisheries Board and Buccleuth Estate (Border Esk). Subcontractors included APEM Ltd, Cefas and Fishskill Consultancy Services.

For more information about Inland Fisheries Ireland, visit . To view the full report, visit: A summary of the key research findings can be found below.


Notes to Editor

Key findings from the project included:

  1. There are nine major genetically distinct and phylogeographic sea trout groups discovered within the Irish Sea. The genetic data showed that sea trout in the Irish Sea originate from a large number of rivers and are distributed widely. Although the majority of sea trout occurred in marine waters in the vicinity of the rivers in which they originated, some migrated up to 300 kilometres for feeding purposes.

  2. Sea trout abundance, based on angling catches, varied considerably over time and between rivers and regions around the Irish Sea but catches were shown to demonstrate a degree of synchronous variation pointing to some common factor/s influencing different stocks or entry period into rivers. The river size and the fishing effort in the area was recognised as a dominant factor controlling the catch. It also discovered that shorter rivers of low alkalinity in areas with poor nutrients, but which had good spawning and nursey areas that were easily accessible from the sea, tended to be the better sea trout rivers.

  3. Sea trout growth, which is strongly tied to environmental factors of temperature and food, is an important measure of subsequent smolting and of marine survival. The spatial variation in marine growth in sea trout in this research was significantly positively correlated with mean annual sea temperature. Fish from more northerly rivers were smaller at age .0+ (finnock) and .1+ (maiden) than fish from southerly rivers.

  4.  Sea trout diet at sea is mainly fish-based and their preference for high protein/lipid prey can be met by sand eel or sprat, depending on which is available. Enhanced feeding opportunities are a major factor in determining the benefit of trout migration to the sea and sea trout are dependent on these keystone prey species (sand eel and sprat), as are many other marine fish and bird species. The study demonstrated that the marine habitat and ecosystems are strongly structured. The combinations of current, depth, seasonal fronts, temperature and salt content within this marine environment appear to influence productivity and growth opportunity for sea trout.

  5. Various models (e.g. hydrodynamic (marine), freshwater production, growth and riverine population dynamic models) were developed over the course of the CSTP project which will contribute to enhancing the decision making framework for managers of sea trout in both the freshwater and marine environments. These will be particularly important in contributing to understanding the potential impact of climate change for sea trout and other species.

 For further information:

Órla Sheils
Communications Manager
Tel: (01) 8842673
E: This email address is being protected from spambots. You need JavaScript enabled to view it.

About Inland Fisheries Ireland

Inland Fisheries Ireland is a statutory body operating under the aegis of the Department of Communications, Climate Action and Environment (DCCAE) and was established under the Fisheries Act on 1st July 2010. Its principal function is the protection and conservation of the inland fisheries resource. Inland Fisheries Ireland promotes, supports, facilitates and advises the Minister on the conservation, protection, management, development and improvement of inland fisheries, including sea angling. Inland Fisheries Ireland also develops policy and national strategies relating to inland fisheries and sea angling and advises the Minister on same.