The 'Octo-Blu' project by the University of Bologna fights against an invasive species that has destroyed shellfish production worth nearly 17 million euros in the Emilia-Romagna region alone since 2022.
Italian scientists have begun releasing thousands of small octopuses into the Adriatic Sea in an attempt to curb the population of blue crabs, an invasive species that has devastated shellfish production along Italy's coast. The team from the University of Bologna believes that the common octopus, a natural predator of crabs, could help reduce the numbers of these voracious crustaceans.
"We chose the octopus because it is a fearsome predator of crabs in nature," said Antonio Casalini, one of the researchers on the project, to AFP. The project, named "Octo-Blu," was launched last year and is funded by the Emilia-Romagna region. The team raises octopus larvae in a laboratory in the port city of Cesenatico and then releases them into the sea near underwater reefs where artificial shelters made of cement and clay have been placed.
Blue crabs, originally from the North American Atlantic coast, arrived in the Mediterranean several decades ago, likely through ships' ballast waters. Their numbers have exploded in recent years, which authorities and fishermen link to sea warming and climate change. With sharp claws with a bluish tint, extremely effective for opening shellfish, they have caused enormous damage in northeastern Italy, one of Europe's main areas for mussel and clam production.
Authorities in the Emilia-Romagna region announced last year that this species has caused nearly 17 million euros in damage since 2022. The agricultural union Coldiretti estimates the total damage for all of Italy at around 200 million euros, with the northern region of Veneto also severely affected. "It eats everything, including young clams that lie on the seabed," says Davide Sanulli, a 64-year-old fisherman and mussel farmer participating in the project. In the lagoon areas along the Po Delta, he adds, "it has caused a real massacre."
Since June, about 80,000 small octopuses have been released into the sea, and the research team plans to double that number by the end of August. "The idea is to create a small community near the coast to better fight the spread of blue crabs," explained Casalini, an aquaculture technician. Blue crabs are excellent swimmers and can weigh up to one kilogram, and they have few natural predators, which researchers are trying to change.
The project, however, has obvious drawbacks. The common octopus is not fond of living in the sandy and warm waters typical of lagoon areas where blue crabs cause the most damage, making its potential impact there negligible. Researchers are aware of this, and other experts have suggested that sea bass might be more effective in fighting the crabs. The team at the University of Bologna is also studying eels, which feed on crustacean eggs, to complement the octopuses' action.
"Blue crabs have incredible reproductive potential and fertility rates," emphasized Pietro Emmanuele, another researcher at the University of Bologna. A single female lays millions of eggs, most of which hatch. Even if only a fraction of the larvae reach adulthood, if an octopus catches even one female, it would already make a difference, he added.
Although there is no direct connection to Croatia, the topic is close to Croatian readers due to the shared Adriatic Sea and similar ecological challenges that invasive species can pose to coastal communities and shellfish production.
