US crayfish invaders spreading plague in German rivers

Published: 11 Aug 09

An immigrant population of crayfish from the United States has invaded the waters of the northern German state of Mecklenburg-Western Pomerania, threatening the local population with a crustacean plague.

The American species, Orcanetes limosus, is native of the US east coast and can be found from Maine to lower Virginia. It’s also a carrier of a lethal crayfish disease, which it has an immunity to, but the German species, Astacus astacus, does not.

Biologist Ines Podszuck said the German crayfish are already considered a vulnerable species and the spread of the American invaders is increasing the threat to their existence. She explained how the Orcanetes limosus has been moving up the Barthe River two kilometres a year. Already, it can be found in a 35-kilometre stretch of water from the small towns of Hövet to Starkow.

An older resident of Hövet recalled when the Barthe River was so full with the native crayfish that children took their buckets to the river and made a meal out of their catch. Now, pesticides and fertilizers have already decimated the population and Podszuck warns it could be wiped out completely by the crayfish plague.

In order to combat their spread, crayfish farmer and researcher Steffen Teufel is advocating the building of low-lying fences that would keep the crayfish in the rivers they have already populated but are permeable for other fish and wouldn’t disturb the canoeing tourists. However, no state funding is available and now Teufel is looking for private sponsors for the project.

The North American crustacean, known as the spiny-cheek crayfish, has been in German waters since 1890, went sport fishermen introduced them to the rivers. Since then, the native species, which can be found across northern Europe, have been repeatedly infected by the crayfish plague.