The EU on Thursday extended current fishing quotas for stocks shared with the UK for another three months in the absence of a post-Brexit deal, which is still being negotiated.
The decision by the bloc's fishing ministers capped an all-night meeting called to set annual catch limits for waters in and around the European Union.
EU and British negotiators are still thrashing out fishing rights as part of talks defining future relations after the UK's departure from the European Union at the end of this month.
While the outcome of the talks still hangs the balance, the EU could not wait any longer to work out its quotas.
"It's a guarantee... without which fishermen would not be able to continue their activities on January 1," explained German Agriculture Minister Julia Kloeckner, whose country holds the rotating EU presidency.
The ministers notably agreed to reduce by 7.5% the 2021 fishing quotas in the heavily exploited Mediterranean Sea, less than the 15% cut proposed by the European Commission because of opposition from Spain, France and Italy.
Britain insists that it will have full control over its waters after this month, when a Brexit transition period with the EU comes to an end.
It is resisting EU demands that European fishing boats continue to have the sort of access they have enjoyed for decades or in some cases centuries.
But even if no EU-UK deal ends up being worked out by the end of the transition period, Britain and the EU are required to manage shared fish stocks under the UN Convention on the Law of the Sea to prevent species being overfished.
The EU and Britain share 125 species of fish which will come under the provisional quota extension, which also applies to stocks shared with non-EU member Norway.
"While this rollover is clearly aimed at dealing with short-term political problems, it is not based on scientific advice for 2021 fishing limits, and ultimately makes the next set of decisions even harder, leaving fish populations in an even worse state," said Rebecca Hubbard, programme director at Our Fish, a European organisation fighting overfishing.