Red crayfish invasion in Malta ‘spreading like hell’, biologist warns

The release of red crayfish in the Maltese wild is wreaking havoc, a biologist has warned, as scientific opinion prepares to declare an ‘invasion’ in a bid to guide environmental authorities on the problem.

Earlier in June, the University of Malta’s Conservation Biology Research Group, led by Adriana Vella, confirmed the presence of the invasive alien fresh water species, the red swamp crayfish, at Chadwick Lakes, while warning of the implication it has for biodiversity.

Known by its scientific name as Procambarus clarkii, the species introduced in the Maltese fresh water habitat by “some careless human action”, holding that local natural fresh water communities may be affect as a result of its presence.

Biologist Alan Deidun said the species is now “spreading like hell”.

“The species is popular locally within freshwater aquaria and also for consumption purposes. As a result of the intentional release in the wild by irresponsible individuals, the species, along with a number of other closely-related species, is now present throughout the islands, wreaking havoc to freshwater species such as the painted frog and freshwater crab.”

Deidun said the crayfish has been listed by the EU as one of the most invasive freshwater ones. “We are in the process of releasing a comprehensive scientific manuscript on such an invasion which will guide the Environment and Resources Authority on possible intervention and control steps to be taken,” Deidun said on Facebook.

The University’s Conservation Biology Research Group said observations of this species confirmed its opportunistic feeding of tadpoles and other species found in the fresh water environment.

Various non-native species have been recently discovered in the marine environment, including the Cocoa Damselfish, Dory Snapper, Indo-Pacific Sergeant, Sergeant Major, African Sergeant, Lowfin Chub, Niger Hind, Monrovia Surgeonfish, Indo-Pacific Punctuated Flatworm, Lionfish, and Squirrelfish.