Sweden's gastronomic love-affair with crayfish is turning into a lethal attraction as an import of crayfish breeds contaminate the country's lakes and kill off the stocks.
May not look particularly appetizing, but the Swedes love the critters
Swedes worship crayfish, holding large parties every summer to celebrate the little red shellfish in a feast that is as important for its rituals as its culinary delight.
But as the crayfish fishing season draws to a close in Swedish lakes and the breeding season gets underway, researchers are expressing concerns that stocks may once again be under threat from a deadly plague that could be spreading out of control.
"Many people were happy this summer when they caught large crayfish in their traps. But the fact that there were so few small ones means that stocks could be threatened come next year," Lennart Edsman, a crayfish researcher at the National Board of Fisheries, told AFP.
Researchers have for the past five years been worried about the spread of the fungal disease, which has been present in Swedish waters to varying extents for almost a century.
But their fears are now growing as people illegally implant an imported variety of crayfish, called signal crayfish which carry the plague, into lakes that are home to Sweden's domestic variety, called noble crayfish.
In the past, fisheries authorities restricted fishing and imposed minimum size requirements, but all restrictions were lifted in 1994, to the regret of some.
"People are beginning to suggest that maybe we should introduce restrictions again," Edsman said.
A gastronomic feast
Crayfish mature in late summer, making an annual return to the table which is widely celebrated with a crayfish party, or "kraeftskiva".
Swedes eat more crayfish than anybody else in the world -- some four million kilos per year, or about a half kilo (one pound) per inhabitant, most of which is consumed in August during the crayfish party season. "No other country comes even close when it comes to the amount eaten," Edsman said.
Boiled in a decoction of dill and then served cold on a heaping platter placed in the middle of the table within everyone's reach, crayfish are eaten with bread, a matured hard cheese and plenty of schnapps. Raucous drinking songs, funny hats with crayfish designs and paper lanterns are de rigueur.
Swedish Princess Victoria, left, shares a light moment with US Chemistry Nobel Laureate William S. Knowles from the United States, during a banquet
Measuring about 10 to 12 centimeters (four to five inches), crayfish are finger food: no matter how distinguished the dinner guests, they delight in sucking the juices from the underside of the crayfish before breaking off the claws and tail and sucking out the meat, unmindful of the juices dripping down their chin and wrists.
Crayfish imports sound death knell
The Swedish tradition of eating crayfish dates back to the 1500s, when German chefs working for the royal family are believed to have introduced the delicacy.
But the dish only spread to the broader public in the late 1800s, when it became so popular that over fishing threatened the stocks and authorities limited the period when they could be fished to a few weeks in August.
In 1907, crayfish imported from Finland for a party but which were not eaten because they had spoiled were thrown into Stockholm's Lake Maelaren, infecting Sweden with the crayfish plague for the first time. Over the years it killed off a large share of the noble crayfish.
In 1969, North American signal crayfish were transplanted into Swedish waters to replace the decimated stocks. Signal crayfish were chosen because their taste is similar to that of the noble crayfish and because they were believed to be resistant to the plague.
But that turned out to be incorrect. In fact, all signal crayfish are carriers of the disease, and they can die of it too, a fact unknown even to many Swedes.
As a result, people continue to implant signal crayfish into lakes with noble crayfish in the hopes of increasing their catches -- and in some cases unwittingly contaminate the waters.
Costly delicacy under threat
The result is disastrous: once a lake is infected, it wipes out all the noble crayfish. And as long as there are signal crayfish in the water the lake will remain contaminated. "Many people think the signal crayfish population is doing really well, but it's not," Edsman stressed.
Already a costly delicacy, any threat to stocks could send prices soaring further: come August, fresh noble crayfish sell for about 600 to 800 kronor a kilo ($82-111, €66-88), compared to around 250 kronor for signal crayfish and as little 40 kronor for those imported from China, Spain and Turkey.