Blue Crabs Have Taken Over the Adriatic Sea. To Fight Them Off, Italian Researchers Just Released Thousands of Baby Octopuses

Blue crabs have invaded the Adriatic Sea, wrecking Italy’s ecosystems and fishing economy. To fight the non-native species, government officials and researchers have recruited an eight-armed ally. This summer, they’ve released into the sea tens of thousands of lab-hatched baby octopuses, which will grow up to be natural predators of the pesky crustaceans, according to a statement, per a translation by Smithsonian magazine.

Blue crabs are native to the Atlantic Coast of the Americas. They likely hitched a ride to the Mediterranean Sea—and its northernmost arm, the Adriatic—via ships’ ballast water, carried for stability purposes. The crustaceans were first spotted in the Mediterranean in the early 1900s, but their numbers and range have surged in the past decade.

Now, the cerulean-colored crabs are decimating populations of local mussels, clams, crustaceans and fish. They’re also destroying fishing equipment with their strong claws. In 2024, experts estimated that the species had caused approximately $116 million in economic damage in Italy.

To address this emergency, the local government is funding an experimental project conducted by the University of Bologna called Octo-Blu. The project started in 2024 to understand whether the common octopus could slow the spread of blue crabs. Octo-Blu researchers picked the common octopus because of its hardy and quick-reproducing nature, and because the project can contribute to the existing population, Antonio Casalini, an aquaculture researcher at the University of Bologna, tells Scientific American’s Gennaro Tomma.

Quick fact: What are Italians doing with all those blue crabs? Few Italians will eat the crustaceans, which are prized in the U.S. Fishers in the European country had been incinerating any pests they unintentionally hauled up, but recently, many have turned to exporting their unwanted blue crabs, reports the ’ Colleen Barry.

After roughly two years of studying the crab species, developing octopus breeding techniques and investigating the dynamic between the two animals, the Octo-Blue team released the first octopus hatchlings on June 11 and 17, according to the statement. Last month, researchers released even more of the young creatures, in their paralarval stage, along with a female octopus. So far, they’ve put at least 130,000 octopuses into the Adriatic, per Scientific American.