After years of fighting invasive American red swamp crayfish in Berlin, the previous approach is being put to the test. Shortly before the impending warming of the waters, a decision should be made as to whether fishing is still necessary. That says Derk Ehlert from the Senate Department for the Environment, Mobility, Consumer and Climate Protection. In addition, there is a debate as to whether scientific monitoring will take place at selected locations. “It’s about checking whether the catch actually causes a lasting reduction in stocks,” said Ehlert.
It was said that no fisherman and no company had permission to fish in the affected waters this year. “It’s not necessary in April either, because it’s still relatively cold. The really effective catch usually doesn’t start until June,” said the wildlife officer.
In recent years, the catches have therefore been declining. However, experts assume that a further spread of swamp cancer in Havel, Dahme and Spree cannot be prevented.
Monitoring by the Fisheries Authority showed an increase to 31 proven occurrences in Berlin last year. These include the Teltow Canal, the Unterhavel and the Landwehr Canal, as the Senate Department for the Environment replied to a parliamentary question.
At previous hotspots – waters in the Britzer Garden and in the Tiergarten – around 840 kilos of swamp and camber crabs were caught last year. In contrast to the shallow lakes and watercourses there, many other bodies of water are not considered suitable habitat. Rather, the crabs use them to migrate.
As an omnivore, the swamp crab has “serious adverse effects” on amphibians, plants and invertebrates and the overall species composition of a body of water, according to the Senate response.
The approximately palm-sized swamp crabs are probably descendants of abandoned animals, for example from aquariums. They are considered extremely voracious and multiply very quickly. Their occurrence went largely unnoticed in Berlin until August 2017 when migratory swamp crayfish were sighted in the Tiergarten.
The animals are actually found in the southern United States and northern Mexico. Their containment is required across the EU. Since the crabs are edible, they have also been marketed as a regional delicacy in Berlin in recent years. (dpa)
