A small silver fish, vital to the North Sea’s ecosystem, takes center stage this week as the European Union and the United Kingdom square off in a landmark post-Brexit fishing rights dispute.

The contentious arbitration case over sandeels is seen as a crucial test for future litigation between Brussels and London in the high-stakes fishing industry, experts say.

The hearing, taking place at the Permanent Court of Arbitration (PCA) in The Hague, marks the first courtroom trade dispute between the 27-member EU bloc and the UK since Brexit was finalized in 2020.

At the heart of the case is Britain’s decision last year to ban all commercial sandeel fishing in its waters, citing environmental concerns. The UK argued in court filings that "sandeels are integral to the marine ecosystem of the North Sea," warning that climate change and overfishing have placed the species at risk of further decline. This, in turn, threatens other species reliant on sandeels, such as Atlantic puffins, seals, porpoises, cod, and haddock.

The EU, however, accuses the UK of breaching commitments under the Trade and Cooperation Agreement (TCA), which governs post-Brexit relations. The TCA allows EU fishing fleets access to British waters during a transition period set to end in mid-2026, after which access will be subject to annual negotiations.

“The EU does not dispute the UK’s right to implement conservation measures,” EU lawyers stated in court documents. “However, this dispute arises from the UK’s failure to uphold its commitments under the agreement.”

Brussels argues that the UK has not implemented “evidence-based, proportionate, and non-discriminatory measures” in restricting EU fishing vessels’ access to British waters for sandeels. The case has significant implications for Denmark, whose fishing fleet accounts for 96% of the EU’s sandeel quota, valued at approximately £41.2 million (€49 million) annually.

“The loss of access to fisheries in British waters could harm relations with the EU, particularly Denmark, potentially leading to job losses and economic hardship for fishing communities,” EU lawyers warned.

Political and environmental stakes

The arbitration hearings, set to last three days, are being held at the PCA’s headquarters in the historic Peace Palace in The Hague. Established in 1899, the PCA is the world’s oldest arbitration tribunal and resolves disputes under treaties such as the UN Convention on the Law of the Sea.

According to Joel Reland, a senior researcher at the UK in a Changing Europe think tank, the EU’s decision to pursue legal action underscores the political and economic importance of fishing rights to influential member states like France, the Netherlands, and Denmark.

“For many communities in these countries, access to British waters is essential for their livelihoods,” Reland explained.

The outcome of the case could serve as a bellwether for future disputes as the TCA fisheries chapter approaches its expiration in June 2026. “This is an early warning of the critical importance renegotiating access rights will hold for the EU,” Reland added.

A decision from the PCA is expected by the end of March. Photo by Steenbergs from Ripon, United Kingdom, Wikimedia commons.