The blue crab, which has spread along the Italian coast, is destroying mollusks and causing losses to the fishing industry. To curb its population, scientists have decided to use octopuses grown in a laboratory. They are released into the sea where they can hunt blue crabs.
The blue crab has become a serious problem for the fishing industry in northern Italy. This species originates from the Atlantic. It is believed to have entered the Mediterranean Sea with ballast waters of ships, which can transport marine organisms from one port to another. In the new conditions, the blue crab has settled in and began to spread rapidly.
As reported by The Telegraph, farms in the northeastern Italian regions of Emilia-Romagna and Veneto, which border the Adriatic Sea, have been particularly affected. Crabs eat commercially valuable mollusks, including mussels, and also damage fishing nets. Economic losses are estimated to have already reached about 200 million euros. In some areas, mollusk production has decreased by 70%, and individual aquaculture farms have been forced to close.
The problem is complicated by the fact that in its new waters, the blue crab has few natural enemies and reproduces quickly. The blue crab also continues to explore new territories. It was recently discovered in the Po River near the city of Guastalla, approximately 160 kilometers from the mouth. This is the farthest penetration of the species into freshwater recorded in Europe.
Researchers suggest that crabs may be seeking new territories due to overcrowding: when there are too many of them, larger individuals start eating smaller ones, so some animals look for new places.
Italian authorities are already trying to reduce the number of blue crabs by encouraging their capture and consumption. They have appeared in supermarkets and fishmongers, and restaurants use them in salads, pasta, and other dishes. However, the scale of capture is not yet sufficient to significantly affect the population.
Scientists are now testing another approach — using a natural predator.
As part of a separate project, researchers from the University of Bologna, together with the authorities of Emilia-Romagna, released about 130,000 young octopuses (Octopus vulgaris) into the Adriatic Sea.
Octopuses are bred in laboratories and released not as adults, but shortly after hatching, when their size is only a few millimeters. To increase their chances of survival, researchers also created artificial shelters on the seabed.
Depuis plusieurs années les crabes bleus ravagent les côtes de la Méditerranée. Et si cette espèce prolifère c'est parce qu'elle n'a pas de prédateur naturel. Des chercheurs italiens ont trouvé une solution en misant sur un adversaire redoutable : la pieuvre !
Julie… pic.twitter.com/ifToQTrA37
The choice of octopus is not accidental. In the wild, it actively hunts crustaceans. According to scientists, an adult octopus can catch and eat up to four crabs per day.
However, it is not yet known whether this method will be effective. About 99% of octopuses die at an early stage of development, so only a small portion of the 130,000 released individuals will survive to adulthood.
Despite this, researchers believe that octopuses can still affect the number of blue crabs. A single female crab is capable of laying 1.5–2 million eggs. Therefore, as scientists note, even if an octopus eats one female, this can prevent the appearance of a large number of new crabs.
The current release is only the first stage of the experiment. Scientists plan to continue breeding octopuses in the laboratory and releasing new batches into the sea, while evaluating their survival rate and impact on the blue crab population.
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