Crayfish season begins amid warm waters and plague concerns
The crayfish season in Finland opens nationwide on Tuesday, 21 July, at 12:00, with experts predicting normal catch levels despite ongoing concerns over the spread of the deadly crayfish plague. The season will run until 31 October, as Yle reports.
Warm waters boost crayfish growth
Exceptionally warm lake temperatures this summer have created ideal conditions for crayfish, according to researchers. Yle cites long-time crayfish researcher Japo Jussila from the University of Eastern Finland, who notes that water temperatures between 18–22 degrees Celsius reduce stress on crayfish, allowing them to conserve energy for growth rather than migration. The prolonged warmth has also accelerated reproduction and moulting, with male crayfish in many areas already moulting twice and females once after laying eggs.
In Hauho, preliminary tests by fisheries advisor Petri Mäkinen from the Häme Fisheries Centre yielded promising results. Yle reports that large, healthy signal crayfish—some measuring around 13 centimetres—were caught in Lake Pyhäjärvi, with no signs of crayfish plague detected. The lake’s clear, rocky waters provide favourable conditions for signal crayfish, though the species has contributed to the decline of Finland’s native noble crayfish.
Plague risks and responsible fishing
The crayfish plague, carried by invasive signal crayfish, remains a major threat to aquatic ecosystems. Jussila warns that the disease can spread via nearly any wet material, including fishing gear, swimsuits, and even boats. While Finnish crayfishers generally clean their traps and equipment, he emphasises the need for broader vigilance to prevent cross-contamination between water bodies.
The Finnish Fisheries Association states that crayfish catches this season are expected to be normal (Yle, MTV Uutiset). However, anglers must obtain a permit from the water area owner and, if aged 18–69, pay a fisheries management fee. Those who turned 65 by the end of 2023 are exempt from the fee (MTV Uutiset).
Protection of noble crayfish
The native noble crayfish, now highly endangered, has been granted indefinite protection in state-owned waters since last summer. As a result, the state only sells crayfishing permits for waters where signal crayfish are present (Yle). In Kanta-Häme, for example, only one lake and one river are estimated to still host noble crayfish populations, with the plague having devastated their numbers elsewhere.