Italian scientists have released more than 130,000 laboratory-reared baby octopuses into the Adriatic Sea in an innovative biological control effort to combat the invasive American blue crab, which has devastated fisheries and ecosystems across the Mediterranean.

The project, named Octo-Blu and run by the University of Bologna together with the Emilia-Romagna regional government, released the common octopus paralarvae — freshly hatched octopuses just a few millimeters long — into coastal waters off the towns of Cesenatico and Riccione, an area heavily impacted by the blue crab invasion.

Under optimal circumstances, a one-kilogram adult common octopus can consume up to four medium-sized blue crabs per day, making the species a potentially powerful natural predator against the invasive crustacean. The researchers also installed artificial dens to provide additional shelter for the newly arrived cephalopods.

"We are not introducing a new species but working on strengthening the population of a native species already naturally present in the Adriatic," said Antonio Casalini, an aquaculture research technician at the University of Bologna.

Blue crabs were first spotted in the Mediterranean Sea in the last century but began causing serious damage about a decade ago when their population surged. The crabs pose a dual threat to native biodiversity and the fishing industry, with hundreds of fisheries closing along Italy's coastline. The Italian government has funded efforts to "contain and combat" their spread.

However, marine ecologist Gianluca Sarà of the University of Palermo cautioned that while the idea is "powerful" and "great," the practical impact could be "absolutely negligible." Octopus paralarvae typically have a mortality rate of around 99.9 percent, meaning only a tiny fraction of the 130,000 released will survive to adulthood.

Casalini acknowledged the long-term nature of the project and stressed the team chose the common octopus because it is particularly hardy and quick-reproducing, with females capable of producing hundreds of thousands of eggs. The researchers plan to continue releasing paralarvae as they produce more, with the approach intended to control rather than eliminate the invasive crab in conjunction with other management strategies.

Sources