Public asked to report sightings of invasive Atlantic blue crab

The Department of the Environment, the University of Gibraltar and Project Tiderise are calling on the public to report sightings of the invasive Atlantic blue crab (Callinectes sapidus) in Gibraltar’s waters.

Native to the western Atlantic Ocean, the Atlantic blue crab is believed to have arrived in the Mediterranean through ballast water from ships. Its spread has been aided by warming sea temperatures and marine traffic.

The species poses a threat to local marine ecosystems. In the Mediterranean, it has been known to damage fishing nets, feed on native species and disrupt ecological balance.

Members of the public are encouraged to report sightings of the crab, whether alive or dead, including carapaces, body parts or full specimens. Reports should include the date and location, the number observed, behaviour such as feeding or burrowing, and photographic evidence or a description where possible.

Sightings can be reported by calling +350 54011307 or by scanning a QR code to submit information via the NEMO app. Anyone under the age of 18 is advised to report sightings with the help of an adult.

The Atlantic blue crab can be identified by its flat body, which can reach up to 23cm in width, bright blue claws (particularly in males), red-tipped claws and nine sharp spines on either side of its shell. Its rear legs are shaped like paddles, and it typically inhabits shallow coastal waters, estuaries, lagoons and bays, tolerating both fresh and saltwater environments.

The species is omnivorous, feeding on fish, plants and molluscs, and is most active at night and dusk. It commonly burrows into sandy seabeds.

The initiative forms part of a citizen science effort to track invasive species and protect Gibraltar’s marine life.