Britains looming exit from the European Union threatens to spark a new fishing war one that risks depleting stocks at a moment when warming seas are already stressing aquatic populations.

Newly sworn-in British Prime Minister Boris Johnson has vowed to take his country out of the bloc by the end of October with or without a deal. That raises the possibility of fresh conflicts as European and British trawlers compete for catches in once-shared fisheries and regulatory enforcement falls to the wayside.

A so-called no-deal Brexit would pull the United Kingdom out of the EUs common fisheries policy and could affect nearly every fishery and species caught commercially in the Northeast Atlantic, said Michael Harte, a professor and fisheries policy expert at Oregon State University.

From scallops to mackerel to haddock and cod... the stocks of all these fish are shared by the EU and the U.K., Harte said in an email. In a worst case scenario these stocks could be decimated as each country refuses to recognize fishing quotas imposed by the other.

With a hard deadline for Britains divorce from the 28-member union less than three months away, tensions are rising. European Union officials passed new rules to compensate fishermen in case British waters are suddenly closed off. In July, Didier Guillaume, Frances agriculture minister, warned Johnson against banning European boats from Britains teeming fisheries.