This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: From a fishing trawler in the Adriatic, Italian scientists gently release thousands of tiny octopuses in the hope of fighting an invasive crab species that has devastated local fisheries. A team from the University of Bologna is betting that the common octopus can help contain the burgeoning population of blue crabs—a voracious crustacean that has ravaged shellfish production in the Adriatic.
"We chose the octopus because, in the wild, it is a formidable predator of crustaceans," Antonio Casalini, one of the researchers, told AFP. Native to the North American Atlantic coast, blue crabs arrived in the Mediterranean decades ago, likely transported via ships' ballast water. But their numbers have ballooned in recent years, with the government and fishing groups linking the boom to warming waters and climate change.
With sharp, blue-tinted claws that are particularly adept at prying open shells, they have wreaked havoc in Italy's northeast—one of Europe's top clam-producing regions. Authorities in Bologna's Emilia-Romagna region said last year that the species has caused almost 17 million euros ($20 million) in damages there since 2022. Farming and fishing group Coldiretti has put the figure at about 200 million for all of Italy, with the northern Veneto region also badly affected.
"It eats everything, including young clams lying on the seabed," said Davide Sanulli, a fisherman and mussel farmer with thick eyebrows and grizzled hair, of the crab. In lagoon-like areas off the Po River delta, "it has caused a massacre," added the 64-year-old, who is helping with the university project. Excellent swimmers and weighing up to 1 kilogram (2.2 pounds), the crabs have few natural predators—something the researchers are hoping to change.
Launched last year and funded by the Emilia-Romagna region, the "Octo-Blu" project seeks to increase octopus numbers as a counterweight to the hard-shelled invaders. The team breeds octopus hatchlings in white water tanks at a lab in the port town of Cesenatico. When ready, the tiny invertebrates are scooped out by the thousands into a large plastic bag and taken out to sea, sometimes using Sanulli's rugged blue fishing boat.
The hatchlings are then released near underwater reefs, where the group has laid cement-and-clay artificial dens to help the octopuses thrive. Some 80,000 have been released since June, a figure the research team is seeking to double by the end of August, hoping to see a few grow into fully developed octopuses. "The idea is to establish a small community close to shore so that it can better combat the spread of the blue crab," said Casalini, an aquaculture technician.
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