Europe’s fishing industry and regulators are having to deal with the effects on fish stocks of rising sea temperatures

The Marine Climate Change Impacts Partnership (MCCIP), which presented its findings at May’s World Fisheries Congress in Edinburgh, says that cultivated fish and shellfish, as well as wild finfish, are now susceptible to the effects of climate change.

Conversely, warmer water species including anchovy, red mullet and sea bass are now found off the south coast of Britain and even in the North Sea. Another, the bib, has extended its range about 200 miles north in the past 20 years.

Global ocean temperatures have risen by at least 1C in the past 100 years, and are rising faster in Europe than the global average. 

Dr Clive Fox, a fisheries scientist at the Scottish Association of Marine Science, who contributed to an academic paper that went into the MCCIP report, says there are “a lot of unknowns around disease and invasive species” from higher water temperatures, with implications for the whole marine food chain.

But it would be misleading to present an entirely negative picture of the possible consequences for industry and the marine environment, he adds.

“There will be winners and losers – it’s a trade-off,” Fox says. He gives the example of the Pacific oyster. When it was introduced on the south coast of England it was too cold for the oysters to breed successfully. “Since it’s got warmer it has started to reproduce and spread outside its original sites. It’s outcompeting some of the native species.”

But is a threat to native species a good thing? “Whether you are in favour of that depends on your point of view, but it is certainly a challenge to what we think of as the natural order,” Fox says.

Silver lining?

The fishing industry is much less sceptical of climate change than 10 or 15 years ago because it can see the effects – and in some cases it has adapted quickly to new opportunities. Red mullet in the North Sea and squid off the west coast of Scotland have become lucrative markets.

But potential conflict with regulators is likely to arise when precautionary measures are imposed on fishing levels that are not necessarily based on stock assessments, Fox says.

Aquaculture – farmed fish including salmon and shellfish – can generally adapt more easily than wild fish to some of the impacts of climate change. Measures such as stronger cages, for example, can be installed to withstand more intense storms.

Speaking in Edinburgh, Richard Benyon, UK minister for the marine environment, said he accepts that climate change is having a big impact on distribution of fish stocks and that this will bring significant challenges for policymakers, fisheries managers and the industry.

But Mike Heath, professor of marine modelling at Strathclyde University, says it is sometimes hard to separate the effects of climate change from those of intensive fishing.

“Industry and science have been working together very constructively in some areas of fishing. It’s when science is used to control fishermen in ways that are seen as unjustifiable by the industry that things can tense up,” Heath says.