"Voracious and almost without predators, the blue crab was first sighted in the Ebro Delta on Spain’s Mediterranean coast in 2012, and since then the population has expanded exponentially, wiping out native species and forcing the fishing industry to adapt and find new markets.
The blue crab (Callinectes sapidus) is a native of the east coast of the United States. It probably found its way into the Mediterranean via ships’ ballast tanks, says Carmen Barberá, a researcher at the Marine Research Centre at the University of Alicante, who is a specialist in invasive species.
When ships are not fully laden they maintain their trim by filling ballast tanks with water, which they later discharge at their destination, dumping marine life from one side of the world to the other. “The fact that the crabs are concentrated in ports such as Castellón and Barcelona is further evidence of this,” says Barberá."
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