Popular fish including cod ‘will become less common and harder to catch’ due to ocean warming

A new study warns that popular types of fish, such as cod, will become increasingly hard to catch as the world’s oceans continue to heat up because of the climate crisis.

These types of fish – the majority of which are vital to the industry’s success – could therefore become less common on land, scientists have said.

As water temperatures rise, fish will be forced to move to new parts of the ocean, meaning they will have to adapt their “historical ranges” accordingly, it was concluded.

The researchers – based in the US and Canada – said this move could have potentially devastating consequences for predator and prey interactions.

Larger fish tend to stay in their old habitats for longer than smaller, more nimble fish because new food sources arrive in these old areas, they noted.

As it stands, predator and prey interactions hamper sea creatures’ ability to react quickly to rising sea temperatures and as waters gets warmer, this will only worsen and could eventually stop fish moving to places where they can flourish.

Unsurprisingly, this will eventually have a long-term impact on the numbers of fish in the sea.

When there are fewer fish, overfishing becomes easier because population growth rates are low, the academics said, adding that while well-known species such as cod may well still be found in the Atlantic in 200 years they will not be as numerous as they are today.

Dr Malin Pinsky, a co-author of the study, which is published in the journal Proceedings of the Royal Society B Biological Sciences, said: “While the species we fish today will be there tomorrow, they will not be there in the same abundance.

“These dynamics will not only be in one place but globally.”

Previous studies of shifting habitat ranges have focused on the impact of a warming climate on individual species, but researchers have largely failed to get to grips with how food-web interactions will affect the pace of change.

In this new research, the team looked at how trophic interactions – the process of one species being nourished at the expense of another – and other dynamics determine how climate change affects species’ ranges.

Using complex computer models, they found many species, particularly large predators, will shift their ranges more slowly than they otherwise would and come under threat in warmer seas.

The computer model included parameters including metabolism, body size and optimal underwater temperature ranges.

Dr Edward Tekwa, the study’s lead author, added of the findings: “The model suggests that over the next 200 years of warming, species are going to continually reshuffle and be in the process of shifting their ranges.

“Even after 200 years, marine species will still be lagging behind temperature shifts, and this is particularly true for those at the top of the food web.”