A landmark study from Bord Iascaigh Mhara has produced the first validated maps of where Ireland’s under-12-metre vessels are fishing off the south coast. The data will be used directly in decisions about offshore wind farms and marine protected areas.
For years, one of the biggest frustrations for inshore fishermen in Ireland has been that nobody could properly show on a map where they work. The big boats have Vessel Monitoring Systems. The under-12s do not. And when it came to planning decisions on offshore wind farms, marine protected areas and cable routes, that absence of data left small vessel operators poorly placed to argue their corner.
That problem has not gone away, but a new study published this month in the scientific journal Ecological Informatics has made a significant dent in it. Researchers from Bord Iascaigh Mhara and the University of Manchester spent the summer of 2024 travelling to ports along the Wexford and Waterford coasts, boarding vessels, and working with skippers to produce detailed, validated maps of their fishing grounds.
The timing was deliberate. Ireland’s South Coast Designated Maritime Area Plan, the framework that will guide where offshore wind turbines can be built off Wexford and Waterford, was moving through public consultation at the time. The plan’s own documentation acknowledged a major weakness: it had limited information on where small boats fish.
BIM set out to fill that gap before decisions were locked in.
How the survey worked
The research team, led by Elizabeth Tray of BIM’s Galway regional office alongside academic geographer Jonathan Huck, developed a digital spray-can mapping application built on admiralty nautical charts. The idea was straightforward: rather than asking fishermen to fill in a form or draw on a paper map, they were interviewed on board their own vessels while in port and asked to use a mouse to ‘spray’ the areas where they fish over charts they already knew from their plotters.
The spray-can approach allowed fishermen to indicate both the rough boundaries of a fishery and, by spending more time spraying an area, the relative concentration of effort. Because the charts showed seabed features, depth contours and navigational marks, participants could locate themselves precisely, which is key to getting reliable data out of any exercise like this.
Crucially, the team also cross-checked what each skipper drew on the screen against the actual waypoints and tracks stored in their vessel plotters. Where a skipper’s spray matched what was in their plotter, the team had confidence the data was accurate. Where it did not match well, that uncertainty was recorded and factored into the final maps using a statistical method called Bayesian analysis, a way of combining multiple pieces of evidence while being honest about how sure or unsure you are.
’73 per cent of the vessels contacted agreed to take part — a strong response rate for any study involving fishermen and their fishing grounds.’
Who took part and what they caught
BIM’s regional officers identified 96 active under-12-metre vessels working from 10 ports in Wexford and Waterford. Of those, 70 — or 73 per cent — agreed to take part, with the remainder either unavailable during the survey window or declining. A further 10 participants from two east Cork ports were also included, bringing the total to 81 vessels and 78 participants.
Across all those vessels, the survey recorded 244 fishing activities covering eight gear types and 19 target species. These were grouped into 11 defined fisheries for mapping purposes. The results showed that lobster potting accounted for the most days fished of any single fishery, followed by brown crab and shrimp. Between them, potting fisheries made up 78 per cent of total days fished across the survey fleet.
Seasonally, fishing effort increased through the summer months and peaked in September before dropping back in winter. Lobster fishing was concentrated in summer, crab peaked in autumn, and shrimp, sprat midwater trawling and gillnetting for demersal species ran mainly through the winter months. This was a pattern broadly consistent with what skippers and industry representatives have long described anecdotally, but which had never previously been recorded in mapped form.
Most fishing was concentrated within 30 kilometres of the coast, though the maps also showed important grounds up to 90 kilometres offshore. Of the four maritime areas being considered for offshore wind development, Area A, off the Tramore and Dunmore East area, recorded the highest number of fishing days and the greatest number of vessels. Area B carried a moderate level of activity; Area C was lower; and no fishing was recorded at all in Area D during the survey period, though the researchers noted that activity was known to occur there and that some skippers in that area had declined to participate.
Validation: why it matters
One of the most significant aspects of the BIM study is that it did not just ask fishermen where they fish and take their word for it. It checked. Of the 244 fishing activities recorded, 147, just over 60 per cent, were validated against plotter data. The average validation score was 81 per cent, meaning that on average four out of five points on the spray map matched what the vessel’s own plotter showed.
Vessels that had a plotter tended to be larger, averaging 9.2 metres compared to 6.6 metres for those without. Smaller vessels without plotters were still included in the survey and their data incorporated into the maps but assigned a neutral weighting that did not increase or decrease overall certainty. The researchers were explicit that excluding smaller boats would have skewed the results in a way that would ultimately underrepresent the most vulnerable part of the fleet.
The Bayesian certainty maps produced alongside the fishing activity maps showed high confidence in the data across most of the study area, with some uncertainty in the southern part of maritime Area B. The researchers described this as a more honest and defensible approach than simply averaging scores. If two participants both give you evidence pointing to the same fishing ground, even if one is less certain than the other, the combined evidence should increase your confidence, not dilute it.
Why this matters to fishermen
The practical stakes of this kind of data are straightforward. Under Ireland’s national marine planning framework, any development that could significantly affect existing fishing activities must show it has tried to avoid, minimise or mitigate those impacts. Without spatial data showing where small boats actually work, that test is very difficult to apply.
The offshore wind industry is expanding rapidly. Ireland has targets of 5GW by 2030, 20GW by 2040 and 37GW by 2050. Meeting those targets means a lot of sea area will be taken up with infrastructure. For under-12-metre fishermen who typically do not venture far from the coast and who tend to target specific inshore grounds with pots, tangle nets and gillnets, the overlap risk is real.
The aggregated fishing activity maps from the BIM study have been made publicly available and are intended for use in planning consultations, including decisions on cable landfall routes, infrastructure positioning and future wind site assessments. The researchers are explicit that the aim is to give planners and developers the evidence they need to route around key small vessel grounds.
There is also a marine protected areas dimension. Ireland is committed under EU biodiversity targets to protecting 30 per cent of its marine area by 2030. Advisory groups identifying candidate MPAs have already flagged that they lack data on where under-12-metre vessels operate and have called for that gap to be filled. The BIM methodology could be applied directly to that need.
‘The maps showed important fishing grounds up to 90 kilometres from the coast — far beyond what planners had previously assumed for small inshore boats.’
What comes next
The researchers acknowledge the limitations of what they have done. The data is a snapshot, not continuous tracking. Seasonal information was self-reported and not independently verified. The survey did not reach all eligible skippers, particularly in Area D, and further fieldwork is planned for 2025 to try to close those gaps. There are also questions around how plotter data, which belongs to the fishermen themselves, should be treated as a validation source, though the researchers argue it is unlikely fishermen would have manipulated waypoints in the short window between being contacted and sitting down for an interview.
Looking forward, the team sees potential in linking the participatory mapping approach with other data sources, including mandatory sales notes, which record landings for vessels of all sizes, and data from sentinel vessels carrying inshore VMS devices as part of a BIM programme already under way. Under EU regulation 2023/2842, vessels under 9 metres will not be legally required to carry VMS until 2029. Until then, approaches like the one BIM have developed are the most practical way of generating reliable data on where the smallest boats in the Irish fleet are working.
The study has also drawn interest from beyond Ireland. The researchers note that the approach could be applied in any country where inshore VMS is not yet in place, which covers a substantial part of the European small-scale fishing fleet, and potentially extended to recreational fisheries and coastal tourism activities that also compete for marine space.
The data is now public
The combined fisheries maps and underlying dataset from the BIM south coast survey have been published on the Zenodo open-access research platform and are freely available for use in planning and consultation processes. Skippers who participated in the survey were consulted on the outputs before publication, and the individual fishery maps, which could reveal the specific grounds worked by individual vessels, have not been made public, in line with commitments made to participants at the outset.
For an industry that has repeatedly found itself unable to prove on paper what every fisherman knows from experience, that the inshore grounds are busy, productive and economically vital to coastal communities, the BIM study represents a meaningful step forward.
