An explosion in the octopus population has been observed off the coasts of Cornwall and Devon, attributed to an extreme marine heatwave that has raised sea temperatures by approximately 5 degrees Celsius above average. This surge in warm-water creatures is creating both opportunities and challenges for the region's fishing industry.
Fishermen in Cornwall and Devon are reporting record profits from octopus catches, with some earning over £20,000 per week. The total catch weight has already surpassed last year's figures by May. However, this boom has led to a sharp decrease in consumer prices for octopus meat in the UK, as local demand is outstripped by supply. Much of the catch is being exported to European countries, such as Spain, where octopus is a more prized dish.
The warming seas are also impacting traditional fisheries. Species like cod and haddock, staples in the UK diet and popular at fish and chip shops, are moving further north into cooler waters. Additionally, octopuses are preying on lobsters and crabs, which are among the South West's most valuable catches. In response, Cornwall has implemented an emergency bylaw restricting larger vessels from using pots that can inadvertently trap and expose lobsters and crabs to predators.
This phenomenon is linked to marine heatwaves, which are exacerbated by climate change and atmospheric 'heat domes' – high-pressure systems trapping hot air. While the natural El Niño weather pattern has been declared in the Pacific and is expected to drive global temperatures higher, its effects on UK weather are not typically felt until the following year.
Experts warn that while the arrival of new species like octopuses can be fascinating, the warming seas present a complex picture for marine ecosystems. Professor Matt Frost of the Plymouth Marine Laboratory noted that declining numbers of native species like cod, along with the potential displacement of native species by new arrivals, can lead to disease and other problems.
The UK's seas have been warming since the 1980s due to global warming, and marine heatwaves are projected to become more common, potentially occurring annually by the middle to end of the century if greenhouse gas emissions are not reduced. In other parts of Europe, rising sea temperatures have also led to an increase in populations of foreign species, such as the silver-cheeked pufferfish, known for its powerful bite and causing alarm in Mediterranean waters.