Month: October 2026

Testing policy before the fleet feels it: From a research tool to a policy instrument

All of the work described below (overview table below) starts from the same place: a skipper deciding where to go fishing next. Not a fleet average, not a grid cell with a fishing intensity in it, but a specific vessel with its own engine, fishing gear, home port, and account to settle at the end of the month. That is what “individual-based” in DISPLACE actually means.

Each fisheries-science model answers a different question, and each has earned its place. Stock assessment models estimate how many fish there are and how hard they are fished, which is the backbone of ICES advice; but because they represent fishing pressure as one number per stock, a closure and a quota cut can look the same to them. Aggregate bio-economic models capture the economics of fleet segments and suit questions where individual behaviour averages out. Static pressure maps show where fishing happens today and are invaluable for that, though by construction they describe a fleet at rest. The questions that motivated this body of work sit between those: which vessels lose their grounds when a rule changes, how far they travel to replace them, what the fuel costs, and where the removed pressure lands instead.

Disclaimer: only simulated data based on heuristics, not on observations (yet). See further development and more robust outcomes soon in the EU Horizon MarineGuardian project

DISPLACE was built for that in-between territory. Conditioned on VMS and logbook data, it simulates each vessel choosing among its known grounds under whatever constraints the scenario imposes, while fish stocks respond spatially to what the fleet does, and the fleet responds back.

The 2020 Baltic study (Bastardie et al., 2020) gave one of the first warnings: closing an area does not mean the seafloor would recover, because vessels shift to the next best grounds and the added pressure there can offset what the closure gained. Seeing that requires simulating behaviour, not assuming it away. The 2025 SEAwise study (Bastardie et al., 2025) showed the complementary result: blanket trawling bans in all MPAs might cut fleet economics by 25-30%, while restricting trawling only where benthic communities are made up of long-lived animals would cost the fleet little. Telling those two options apart depends on knowing each vessel’s real alternatives. The 2022 fuel paper (Bastardie et al., 2022) stated that rebuilt stocks would cut fuel use more than new gear would do, because fuel is spent trip by trip and better catch shortens trips. CAFF and MarineGuardian projects now extend that accounting to fleet renewal and decarbonisation scenarios, helping the sector to commit to a transition path.

Meanwhile, the model keeps travelling 🙂 the Ionian Sea (Maina et al., 2021), western Baltic cod (Rufener et al., 2023), deep-sea VME closures weighed in STECF advice, and offshore wind leases off California, the latter where there is not even a fishing measure tested but someone else claiming the sea.

Looked at together, the arc of these papers is about finding the right unit of analysis for the question at hand. Stock models count fish, economic models track fleets, pressure maps map square kilometres. Some questions need all three scales at once: a skipper’s reaction, the next ground chosen, the fuel burned, the fish removed, the seafloor swept. As policy keeps redrawing the map of European seas, decisions are made at that scale, vessel by vessel.

DISPLACE (2020–2026)

project numberIndividual
Vessels		Effort displ.Fish pop. dyn.Bio-econ.Energy/climateBenthos/seafloorMSE spatial plansRegion
[1]●●●●○●●Baltic/Kattegat
[2]○●●●●●●EU-wide
[3]●●●●○○●Ionian Sea
[4]●○●●●○○EU/North Sea
[5]○○○○●○●EU-wide
[6]●●●●○○●North Sea
[7]●●●●○○●W. Baltic
[8]●●●●○○○NE Atlantic
[9]●●○●○●●EU deep-sea, NE Atlantic
[10]●●○●○●●EU-wide
[11]○●●●●○●EU-wide
[12]●●●●○●●NE Atl. + Med
[13]●○●●●○●Denmark to Atlantic & Arctic
[14]●●○●○●●E. Mediterranean
[15]●●●●●○●California

● = core; ○ = secondary.

[1] Bastardie et al. 2020, Fish. Res. 230:105681 (Baltic seafloor)

[2] Bastardie & Brown 2021, Mar. Policy 126:104409 (fleet policy risk assessment)

[3] Maina et al. 2021, Ocean & Coast. Manag. (Ionian spatial plans)

[4] Bastardie et al. 2022, Front. Mar. Sci. 9:817335 (fuel use intensity)

[5] Bastardie et al. 2022, Front. Mar. Sci. 9:947150 (CFP ten lessons)

[6] Bastardie 2022, NORDFO report (North Sea)

[7] Rufener et al. 2023, Fish. Res. 268:106853 (W. Baltic cod Essential Fish Habitats)

[8] Vastenhoud et al. 2023, Front. Mar. Sci. 10:1285793 (mesopelagic fish exploitation)

[9] VME socio-economic impact assessment (STECF advice 2023; EWG-24-09; EWG March 2025; Reg. (EU) 2022/1614 closures)

[10] STOA 2024, PE 762.843 (innovative tech for bottom trawling in MPAs?)

[11] Bastardie et al. 2024, Front. Mar. Sci. 11:1352500 (roadmap, changing ocean)

[12] Bastardie et al. 2025, Front. Mar. Sci. 12:1629180 (SEAwise, EU closures)

[13] Bastardie et al. 2026, Front. Mar. Sci. 13:1812898 (fleet renewal & energy transition)

[14] Tsikopoulou et al. 2026, https://doi.org/10.3389/fmars.2026.1769853 Front. Mar. Sci. 13:1769853 (E. Med benthic status)

[15] California offshore wind application (ongoing, w/ UCSB EM Lab)

Energy-efficient fishing already exists. How do we unlock it?

Parts of the EU fishing fleet are under real pressure from marine diesel costs (EUMOFA), and the sector must decarbonise regardless. Facing both without pitting them against each other would keep progress moving.

Encouraging news from our data analysis and modelling work at DTU Aqua: we have already identified some effective levers. They don’t wait on a technological breakthrough, and they don’t require choosing between viable fisheries and energy transition goals.

What the data shows

In the same waters (for example, the ones visited by the Danish fleet), the difference gear choice makes is measurable:

  • Otter bottom trawlers, fishing a mix of Nephrops, cod, plaice and flounder, may burn 0.83 litres of fuel per kilogram of fish landed, generating €4.19 of revenue per litre.
  • Vessels using passive gear (gillnets, hooks, etc.) burn only 0.17 to 0.24 l/kg, and may yield up to €9.57 per litre.

That is a 70–80% fuel saving and more than double the revenue per litre. Two vessels leave the same harbour; one operates at roughly half the energy cost per fish on the dish plate (and those fisheries also use different vessel sizes, see details in Bastardie et al. 2022)

And the gap is arguably even larger EU-wide: in the Mediterranean, bottom-trawling fuel use intensity runs considerably higher than the Danish figures above, so if anything this comparison understates the European potential.

The real policy difficulty: the shocks

To be fair to everyone involved: fuel-price shocks do call for emergency relief. Fishing communities are real, food supply is real, and it is expected that no responsible government would let a sector collapse mid-crisis.

The difficulty is that emergency relief also removes the incentive to make the structural change that would end the vulnerability, and the sector ends up needing relief again at the next price spike. Getting both right simultaneously (solidarity in the short term, energy transition in the medium term) is hard policy design. It is also, we would argue, the central design task of the EU Energy Transition Partnership.

Our modelling consistently points to the same ranking of levers: stock recovery combined with a gear change would reduce fuel-use intensity more than any engine upgrade would in the short term. Supporting fuel-intensive effort while stocks rebuild means paying twice for the same fish (1: for the fuel, 2: for the rebuild). The transition should be seen less as a cost imposed on the sector and more as the exit from the crisis loop.

Extracted from here

Likely three concrete choices, available now

  1. Transition-linked aid? Emergency support stays (for example as in here), but would come with a committed pathway: continue working on, and financing, drag-reduction technology and “precision fishing“, with gear-switching plans agreed with producer organisations, phased realistically.
  2. Reward efficiency with access? Low-fuel, passive-gear fishers earning more euros per litre of fuel could receive preferential access, more fishing days, quota flexibility, etc., making efficiency profitable before the fuel bill punishes inefficiency.
  3. Capital support for retrofits, not just operating costs? Direct EMFAF-type funding and investment toward hybrid retrofits, gear changes, and vessel adaptation, so today’s aid builds the fleet of tomorrow instead of renting the fleet of yesterday (Bastardie et al. 2026).

Stakeholders would agree that each of these would be implementable within existing instruments, and would make sure that each has precedent elsewhere in the EU’s decarbonisation toolbox. Consultation works point to industry readiness, not only a lack of flexibility in the policy framework, as the primary missing feature. The primary obstacles are likely a widespread resistance to change, driven by the high costs and low uptake of commercial feasibility studies. Ultimately, operators’ pervasive fear of losing market access during the transition likely stalls progress. This includes the challenge of gaining flexibility to align each operator’s quota portfolio and capacity with available marine living resources.

When energy prices spike, fuel-dependent industries adjust in stages: absorbing the shock through margins, then coping in the short term, and finally adapting structurally. Cost-effective efficiency investments are routinely delayed because of uncertainty, irreversibility, and the “option value of waiting” (Gerarden et al., 2017).

In fisheries, fuel price shocks manifest primarily as behavioural coping: shifted effort and fishing closer to port, fewer trips and fewer exploratory trips, and accepting lower catches (for example, see Abernethy et al., 2010). In contrast, Structural changes would mean new gear, vessels, and techniques. Today, the EU fleet remains stuck in Phase 2: coping, but not transforming.

An open question

What would make transition-linked support workable in practice, not just on paper? Which conditions feel fair? This is a design problem best solved by consulting the people who will live under the rules. But even when considering alternative viewpoints, one should not ignore the numbers science studies bring to the table.

References and details:

Abernethy, K. E., Trebilcock, P., Kebede, B., Allison, E. H., & Dulvy, N. K. (2010). Fuelling the decline in UK fishing communities? ICES Journal of Marine Science, 67(5), 1076-1085. https://doi.org/10.1093/icesjms/fsp289

Bastardie, F., Hornborg, S., Ziegler, F., Gislason, H., & Eigaard, O. R. (2022). Reducing the Fuel Use Intensity of Fisheries: Through Efficient Fishing Techniques and Recovered Fish Stocks. Frontiers in Marine Science, 9, 817335. (Open access.)

Bastardie, F., Wakeford, R. C., Torreele, E., Aranda, M., Doering, R., Ligas, A., Mele, I., Castresana, J., Gabiña, G., Maes, S. M., Sabatella, R., & Malvarosa, L. (2026). How to ensure sustainable fisheries while renewing the EU fishing fleet for modernization and energy transition? Frontiers in Marine Science, 13, 1812898. https://doi.org/10.3389/fmars.2026.1812898 (Open access.)

Gerarden, Todd D., Richard G. Newell, and Robert N. Stavins. 2017. “Assessing the Energy-Efficiency Gap.” Journal of Economic Literature 55 (4): 1486–1525.

How do we get more fish and profit? Start from the end.

Most fisheries management studies ask: what will happen if we keep fishing as we do? We asked a different question, putting the goal first: What needs to change for both marine biodiversity and fisheries´profit to increase?

We fed two decades of fisheries science into a Bayesian network adapted to EU fisheries. Then we made the best outcome certain and let the model work backwards. This “reverse engineering” showed us what a successful future would look like.

The answer was indicative. Fishing effort on benthic habitats would need to go down. Of 100 possible futures where biodiversity and profit both rise in the EU, 73 include a cut in benthic effort. Almost none include more of it. For the pelagic fleet, 53 out of 100 successful futures show reduced effort. In those successful futures, habitat damage also falls from 77% to 48%. The sea recovers. So does profit.

We also tested the worst case. More benthic effort would lead to profit loss in 61 of the 100 possible futures, and biodiversity loss in 81 of them.

Both tests agree: The path to success would run through less benthic effort. Strong policy would make it happen. If we want more from the sea, we will likely need to leave more of the sea alone.

See the “reverse engineering” (i.e. work backwards to move forward!) study here (Open Access Version) and cite it with:

Bastardie, F., & Brown, E. J. (2021). Reverse the declining course: A risk assessment for marine and fisheries policy strategies in Europe from current knowledge synthesis. Marine Policy, 126, 104409. https://doi.org/10.1016/j.marpol.2021.104409

AI-generated vision for a DISPLACE dashboard: testing fleet economy, seafood provisioning and environmental performances

This is part of the narrative around the virtuous circle: Effort cuts avoid damaging the seafloor integrity > Habitats support the fish we want to catch > Recovered species make each unit of effort more productive > Lower costs stack on top of higher value > etc.

However, the trap is timing. Individual fishers benefit from fishing less only after the stock has recovered, but recovery requires everyone to ease off at once. The market doesn’t provide that coordination. Strong regulation would instead likely provide it.

(Disclaimer: This study was a synthesis of existing knowledge expressed as probabilities… of course not a forecast)