Now the crayfish plague has spread to Öresjö

Crayfish are classified as highly endangered in Sweden and Öresjö has long been one of the few lakes in Sweden with good crayfish fish stocks.

Since 2015, the lake has also been a protected area for crayfish, which among other things means stricter requirements for disinfection of boats and gear used in the lake.

The aim has been to prevent the contagious crayfish plague from entering the water and killing the powerful crayfish population.

But despite that, crayfish plague has now been found in the seawater, which means a certain death for all crayfish that are infected.

Cancer plague in four municipalities

Already at the beginning of September, crayfish plague was found in Sågån in Öresjö's outflow.

The County Administrative Board of Västra Götaland then decided to declare the entire Bäveån water system in Uddevalla and Vänersborg municipalities' crayfish plague, but now Öresjö and upstream lakes and watercourses are also included in the new decision.

The most common way for crayfish plague to spread to water is through the invasive signal crayfish that has been illegally planted out, but it can also be transmitted through fishing equipment that is not cleaned properly.

A declaration of crayfish plague means that all crayfish fishing in the lake is prohibited, and all equipment that comes into contact with the water must undergo thorough disinfection before it is used in other waters.