CLIMATE CHANGE AND UK FISHERIES, WHAT NEXT?

Climate change and UK fisheries, what next? In this analysis, Fish Focus looks at the impact of climate change on UK fisheries.

Climate change and how it affects our environment is one of the most talked about topics of our times, with it likely to have a whole range of significant impacts on our everyday lives both now and into the future.

According to the Intergovernmental Panel on Climate Change, we are already seeing the consequences of one degrees Celsius global warming caused by human activity such as loss of sea ice and desertification. The trend is predicted to continue with future warming estimated to reach 1.5 degrees Celsius between 2030 and 2052.

Such temperature rises may not seem like much, but for the sensitive marine environment it can be the catalyst for driving significant change in the distribution and abundance of fish and other marine life. Not only do such changes have the potential to harm the marine ecosystem, it also impacts upon food security at a time when seafood is the primary source of animal protein for an estimated one billion people.

Whether it be Alaska, Tasmania or the UK, perceptible change is happening in our marine environment. On the south coast of England, fish more traditionally associated with the Mediterranean such as the comber (which looks like a small grouper) and the giant goby are appearing. Cold loving cod are moving further north and warm water species like red mullet are coming in from the south, reaching as far as Scotland. Mackerel are changing their migration patterns and venturing further north than before.

Rising sea temperatures have the potential to cause all kinds of turmoil, including for important keystone species such as sandeels. Temperature variations impact upon sandeel reproductive success and the abundance of their planktonic prey. Sandeels are the bread-and-butter food for many creatures including kittiwakes and commercially important fish such as cod, whiting and mackerel.

On a wider scale, sea temperature increases could impact upon crucially important sea currents, including the Gulf Stream, with grave consequences for our climate. Research has already indicated that the Gulf Stream is weakening.

But as well as distribution and abundance, there are other impacts climate change can have on marine life. Metabolic theory predicts that changes in the ‘living costs’ of fish can affect growth, with fish becoming smaller on average over time as waters warm. For the fishing sector, fish size and supply hit prices, and high prices affect profit and investment, as well as the ability to compete with other fishing interests.

In Scotland, this has possibly manifested itself in recent years with there being an abundance of small haddock on the fishing grounds, which are challenging for processors to handle and market. Whether this current size shift in haddock is purely down to climate change, or is part of a more complex interaction between the environment and fishing activity is a moot point, because what does seem likely is that fish will become smaller in the future due to warming seas.

Climate change can also lead to fisheries conflict. Take north-east Atlantic mackerel for example, where northern coastal states such as Iceland, Greenland, Faroe and Norway have set their own unilateral quotas because as the fish move north, they contend they have a right to their share of the catch.

Mackerel is a ‘straddling stock’ – its range extends across several Exclusive Economic Zones (EEZs) and into international waters. The UK fleet catches more mackerel than any other species, comprising 33% of the total UK catch in 2022 (197,003 tonnes). During the period 2007-2016 the distribution range of mackerel increased threefold and the centre-of-gravity, shifted westward by 1,650 km and northwards by 400 km, resulting in disputes between catching nations about quota allocation (‘zonal attachment’) as fish move across jurisdictions.

There is also the wider ecosystem impact too, and it should be remembered that mackerel is food for other marine creatures and are predators in their own right. Changes in their abundance or distribution related to warmer seas can potentially have significant knock-on effects for the rest of the marine environment.

The same applies to Atlantic bluefin tuna, which has been moving into British waters in big-style over the last few years. Tuna have now been reported as far north as Iceland and Greenland, possibly shifting their distribution in response to the expansion of mackerel. For 2023 the UK was allocated 65 tonnes of bluefin tuna quota by ICCAT, of which 39 tonnes were used to trial a new small-scale commercial fishery.  Projections, under a medium emissions scenario, suggest that ‘habitat suitability’ for this high value fish will increase in the UK EEZ – again resulting in possible fishing disputes between catching nations as fish move across jurisdictions.

A recent report – Climate change risk adaptation for wild capture seafood – produced by Seafish, CEFAS and the University of Aberdeen states:

“Although now a much higher priority than in 2015, climate change is one of many challenges facing the seafood industry and competes with other priorities – some which may represent more immediate existential threats for businesses.”

The report also highlights the importance of continual monitoring and the need for the seafood industry to be dynamic and adapt to change.

Of course, as well as threats, climate change may bring opportunities for UK fisheries. The report –  Informing Scotland’s fisheries policies to be adapted and resilient to climate change and ocean acidification – published in May 2024 by ClimateXChange, Scotland’s centre of expertise on climate change, says species such as anchovy and seabass are projected to become more abundant in Scottish waters. Fishermen may be able to exploit new commercial species that become available in their waters, but they will need to adapt their operations and diversify.

The report states:

“There are also several constraints that inhibit UK suppliers from benefiting from these potential opportunities; domestic consumer preferences in the UK are generally for a limited range of species. Supermarkets can play a major role in this transition by educating consumers about new local commercial species and offering them a wider range of sustainable seafood options. Another constraint is that many of the new commercial species will need to be exported to markets where there is already an established demand. In order to capitalise on these potential emerging opportunities, Scotland needs to establish market access early for these new species.”

However, the feasibility of harvesting new species is easier said than done, given that quotas can act as an obstacle to maximising access to new commercial species due to the inflexibility of quota systems that are based on historical data and agreements between nations. For example, under the EU’s Common Fisheries Policy (CFP), TAC quotas are set annually based upon advice from ICES and