The twin threats of climate change and growing nationalism could lead to an outbreak of conflicts over fish stocks – like the infamous Cod Wars between the UK and Iceland – that could threaten the global supply of food and “decimate” marine ecosystems, experts have warned.

Speaking at the American Association for the Advancement of Science’s annual meeting in Boston on Thursday, a panel of experts said that with the right management and international co-operation the number of fish in the sea and the amount caught by fishing fleets could increase over the coming decades.

However, they warned rising temperatures were prompting many species to move to different parts of the sea, which could threaten some individual countries’ economies and access to food.

And this, fuelled by the growth in nationalist sentiments, could see a new “era of fish wars” as countries compete for stocks.

While individual states might emerge as the winner of a conflict, the ensuing free-for-all – as fleets go after as many fish as they can for fear they would be caught by a rival country’s boats – could be devastating for stocks in the long run.

During the Cod Wars between the UK and Iceland between the 1950s and 1970s, British gunboats were sent to ward off Icelandic boats from disputed waters.

Eventually, it was agreed that Iceland would be allowed to catch any fish within its 200-mile territorial limit, an outcome seen as a victory for Reykjavik.

A more recent trade war erupted in 2010 over mackerel in the North Atlantic between the European Union and Iceland, Norway, and the Faroes.

Michael Harte, a professor of marine geography at Oregon State University, said he had been looking into the “winners and losers” from climate change’s effects on fisheries.

“If we succeed in doing this well, the world’s fisheries can do better than they are today,” he said.

“But if we fail to get it right, the losers will be the people … who depend on fisheries for their food and incomes.

“And they don’t have many other alternatives. If the fish go, they are in trouble.

“If we don’t get it right … we are going to potentially see the resumption of fish wars, a return to over-fished and collapsed fish stocks, decimated marine ecosystems, and perhaps a squandering of a critical food and economic resource.”

In order to manage stocks effectively and prevent climate change from reducing fish stocks, international co-operation would be needed.

But Professor Harte said: “People matter, borders matter, borders that fish ignore matter far less.

“Today we are seeing increasing nationalism perhaps in our global politics.

“This nationalism could in fact hinder the very necessary changes we need to manage fisheries collectively in a global way.”

Asked whether he meant trade wars or military conflicts, he said: “The potential is there for all of those things.

“When looking at whether or not Iceland and the UK will return to the days of the Cod War and the showdowns with the gunships in the North Atlantic, it’s probably maybe not going to happen today.

“But it may happen in other parts of the world where the neighbours are not so friendly towards each other over these fish resources.

“I think what we are going to see though is increasingly the conflict is going to be more of a trade war type.

“That has happened in 2010 and recently is still on going [over] mackerel in the North Atlantic between the UK and European Union, on one side, and then Iceland, Norway and the Faroes on the other side.

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“If these countries can’t agree over the management of these fisheries in all their waters, then the consequences are over-fishing, potentially short-term gains for an individual country but long-term losses to all the players with fewer fish in the future.