A single signal crayfish can infect an entire lake with cancer plague and in the last hundred years, the population of river crayfish has decreased by 97 percent. Therefore, the Marine and Water Authority has extended the action plan to save the species.

In total, the authority is investing SEK 15 million until 2022 to map and reduce the spread of the infectious and hard-skinned signal cancer, which is often planted by thoughtless people.

Experiments in the archipelago - the crayfish are placed in small lakes

At the same time, projects are also underway to strengthen the stock of river crayfish. In the Stockholm archipelago, crayfish are placed in small lakes where they are safe for plague. The County Administrative Board in Stockholm is therefore seeking contact with islanders who want to become a cancer cultivator.

- The goal is to raise awareness so that people can continue to fish and eat Swedish river crayfish even in the future, says Niklas Sjöberg, a fisheries consultant on the Stockholm County Administrative Board.