When explorer John Cabot returned from Newfoundland in 1497, assured who had found seas so full of fish that they could captured with simple baskets weighted with stones. That abundance seemed inexhaustible, but more than five centuries later, British waters are once again starring in a story of marine overpopulation, although with very different protagonists.
An unexpected invasion. For decades, encountering a common octopus off the coast of south-west England was a rare event for even the most experienced divers. However, in just a few years the situation has changed. radically.
What started as a striking increase of sightings has become the largest population explosion of octopuses recorded in at least 75 years. The animals have colonized extensive areas of the British coast, expanding from Devon and Cornwall to Wales, Dorset, Sussex and even Scotland, becoming one of the most surprising marine phenomena that the United Kingdom has experienced in recent times.
Perfect weather and conditions. Scientists believe that this expansion is the result of several factors that have coincided at the same time. The juvenile octopuses probably arrived from breeding areas around the English Channel and northern France, but the real difference has been the progressive warming of British waters.
Mild winters and warmer breeding seasons have allowed them to survive in much greater numbers and, more importantly, to begin to reproduce successfully in UK waters. The appearance of juvenile specimens confirms that they are no longer simply occasional visitors, but rather a population capable of completing their entire life cycle on these coasts.
The big losers. The massive arrival of octopuses is having devastating consequences for part of the traditional fishing. These animals are extraordinarily efficient predators and consume huge quantities of seafood every day. Fishermen began finding empty traps, missing lobsters and ruined catches. In some areas, those who depended on crustacean fishing have seen plummets in between 70% and 100% of their catches.
In fact, some businesses have closed and some owners have even sold their boats. The researchers they calculate that octopuses are consuming tons of seafood daily, altering a food chain that had been functioning relatively stable for decades.
The same plague that ruins some enriches others. The paradox is that the crisis has also generated an economic opportunity unexpected. Where lobsters and crabs were once caught, octopuses now abound. Many fishermen have quickly adapted their gear and have begun to catch them to supply a growing demand in European markets.
The result has been spectacular. Brixham recently sold more than 100 tons of octopus in a single day, generating more than half a million pounds in sales. Some professionals claim that they are obtaining income several times higher than what they achieved with traditional fishing, causing a real fever to catch octopuses along the coast.
A reorganized ecosystem. The phenomenon goes far beyond the fishing economy. Octopuses are profoundly altering the relationships between species. While they consume large quantities of crustaceans and mollusks, they have also become food for seals, conger eels and Risso’s dolphins.
The researchers describe the situation as a complete reconfiguration of the marine ecosystem, a process in which each change triggers new ones. The feeling among scientists is that British waters are going through a period of ecological transition in which the rules that seemed established for generations are no longer valid.
The big difference from previous invasions. Although similar population explosions were already recorded at the beginning of the 20th century, in the 1930s and 1950s, researchers believe that this time the situation can be different. In previous episodes, the octopuses ended up disappearing when conditions changed again.
Now, however, winters cold enough to drastically reduce their populations have been going on for more than a decade without production. Evidence of local reproduction and the presence of young specimens suggest that octopuses may have ceased to be occasional visitors and become permanent inhabitants of British coasts.
Preparing for a new reality. The magnitude of the phenomenon is already forcing the authorities to react. In Cornwall, for example, they study emergency restrictions to limit the number of boats dedicated to capturing octopuses for fear of excessive exploitation of a population that, paradoxically, seemed inexhaustible just a few months ago. Meanwhile, scientists, fishermen and resource managers are trying to understand what this transformation really means.
The big lesson is that ocean warming not only changes temperatures or currents, but can change them completely. who dominates an ecosystem. And on British shores, the new protagonists seem to be animals that until very recently were a rarity and that are now devouring everything in their path.
Careful, Galicia.
Image | prilfishPixabay
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