Native River Crayfish on Brink of Extinction Amid Invasive Species Crisis
Sweden's native river crayfish faces extinction due to invasive species and illegal activities.
Key Points
- • Native river crayfish population in Sweden has plummeted from 30,000 to fewer than 600.
- • Signal crayfish populations now estimated at 10,000 to 15,000 and responsible for spreading disease.
- • 239 illegal releases of signal crayfish documented in Värmland from 2000 to 2024.
- • Crayfish industry worth 450 million SEK in imports amid overfishing concerns.
In Sweden, the native river crayfish population is nearing extinction due to a severe crisis triggered by the crayfish plague and the burgeoning presence of the invasive signal crayfish. Originally, Sweden’s flodkräfta population was around 30,000; however, recent studies indicate that fewer than 600 remain, marking a catastrophic decline of approximately 98% since the introduction of the signal crayfish in 1960.
The primary culprit behind this alarming trend is the crayfish plague, spread by the invasive signal crayfish, whose populations have surged to an estimated 10,000 to 15,000 individuals. Notably, illegal releases of signal crayfish in Värmland are behind significant damage, with evidence showing such releases occurred in 239 different water bodies between 2000 and 2024. Crayfish expert Lennart Edsman from the Swedish University of Agricultural Sciences (SLU) highlighted that in the Värmland and Dalsland regions, native crayfish populations dropped from 430 in the early 2000s to just 60 today.
The implications of these changes are profound. With declining native populations, Sweden, which imports about 70-80% of its crayfish, faced a remarkable import value of 450 million SEK in 2023, while domestically caught crayfish—largely signal crayfish due to their dominance—were valued at 300 million SEK. Edsman emphasized the need for consumers to choose flodkräftor when available as a means of support, while also warning against the continued spread of signal crayfish.
Despite existing bans on further introductions, the ecological and economic damage has already been done. Overfishing and high consumption rates within Sweden are complicating factors; recent complaints regarding the small size of the crayfish have been attributed to these practices. As the situation unfolds, it underscores the critical need for conservation efforts to protect the remaining native flodkräfta.