The Noble Crayfish

The Noble Crayfish (Astacus astacus) is the only freshwater crayfish native to Finland - a slow-growing, long-lived decapod crustacean (not a fish, but treated as one in Finnish angling tradition) that has shaped lakeside summer culture for centuries. Adults are dark brown to almost black above, sometimes with a green or reddish tinge, and paler below; the claws are long, almond-shaped and warty, often with a red wart at the claw joint - exactly where the invasive Signal Crayfish (Pacifastacus leniusculus), with which it is so often confused, has a white wart in a white-turquoise patch. A row of small spines along the groove between head and carapace, which you can feel with a finger, is the surest test: the Signal Crayfish has none.

In Finnish it is rapu, and few foods are more woven into Finnish summer than the boiled crayfish of late July. The season opens at 12:00 on 21 July by national fisheries law, and the weeks that follow are the high ritual of rapujuhlat - crayfish parties on lakeside terraces with bibs, candles, dill-laden boiling broth, dark rye bread, butter on toast, and small, ice-cold glasses of schnapps drunk with ceremonial little songs between every claw. To catch your own, by trap or by hand from a boat at dusk, is one of the deep summer rites of the Finnish lakeland.

Ecologically, Noble Crayfish are nocturnal benthic omnivores of clear, cool, well-oxygenated freshwater. They burrow into clay banks, hide under stones and submerged timber by day, and forage at night for invertebrates, plant material, carrion and the occasional dead or weakened fish. Mating occurs in autumn; females then carry eggs in berry under the abdomen all winter, releasing tiny juveniles in late June. Wild Finnish stocks have been devastated since the 19th century by crayfish plague (Aphanomyces astaci) - a water-mould that introduced Signal Crayfish can carry without visible symptoms - and the species is listed as Endangered (EN) on the Finnish Red List. Many southern lakes today hold only Signal Crayfish; recovering Noble Crayfish populations exist, but they are isolated, plague-vulnerable, and managed with care.

Noble crayfish (Astacus astacus, Finnish jokirapu) are caught in baited traps (merrat). In mainland Finland the open period runs from 21 July at noon through 31 October; water and permit rules can restrict it further. The national Fishing Decree sets no crayfish minimum size. Check local sizes, quotas and allowed traps rather than assuming a universal 10 cm rule.

A noble-crayfish outing needs specific permission from the fishing-rights holder. Since summer 2025, Eräluvat has sold crayfishing permits only for signal-crayfish waters; this is not a nationwide ban on noble-crayfish harvest. The state fisheries-management fee generally applies at ages 18–69; anyone already aged 65 by 31 December 2023 remains exempt (Eräluvat).