Crayfish on a plate! Why invasive species deserve gastronomic attention
Crayfish soup, crayfish butter, stuffed crayfish shells... 19th-century cooks still remember recipes made from Czech crayfish that are now protected by law, from traditional use in the kitchen, but mainly from environmental change and the effects of globalisation. "For a long time, crayfish lived in our country as native species, the river crayfish and the stone crayfish, but due to water pollution and land reclamation, they have begun to decline significantly. Finally, they became a protected species," said Tomas Görner from AOPK, who specialises in invasive species of plants and animals, including immigrant crayfish.
"In Scandinavia, they once decided to introduce non-native crayfish to replace the population of endangered native crayfish. The same thing happened in the 1980s in the Czech Republic, to supplement the signal crayfish, without knowing at the time how it would harm European species. "When different crayfish populations collide, there is a problem. Ours are not as resilient, so they usually die."
The danger signal
The controversial Signal Crayfish (Pacifastacus leniusculus) is native to North America and inhabits mostly the south and southeast of the Czech Republic. In doing so, it spreads a threat called the crayfish plague. "Crayfish plague is transmitted only to our native species. Once it's in a river, the crayfish will die out. The remaining plague spores then have nothing to latch on to, so they gradually disappear. At that point, the watercourse can be recolonised by the river crayfish population," Tomáš described while pitching the litter.
"The signal crayfish are immune to the plague. In addition, they are better able to cope with higher temperatures and do not mind dirty water, unlike the river crayfish, which is an indicator of clean water and needs a certain temperature and a certain proportion of oxygen and minerals," Tomáš added the reasons why the signal crayfish have managed to dominate Czech ponds and rivers. The most frequent inhabitants are at dams, rocks and sandy river beds. However, the success of the hunt also depends on the depth and sunlight where they dive to the top. Raw meat or offal is used as bait.
Good luck comes to those who prepare! In less than two hours we met the signal crayfish in person, and five were caught. "The hallmark is the signal white spot on the claw joint. Feel them, they are smooth and without growths. In contrast, the river crayfish has claws and shell that are bumpy," Tomáš pointed out. Suddenly we understood why it was worthwhile to fish alongside an expert:
"The red colouration of the claws also characterises the river crayfish. The colour is therefore misleading, especially for crayfish that get dirt on them in ponds. Therefore, all distinguishing features should be assessed, otherwise there may be confusion and enormous damage."
Regulate and protect
In the case of the signal crayfish, conservationists make it a point to monitor and limit its occurrence. Once every two years in the autumn, a survey is carried out in the area, to prevent overpopulation. "The crayfish are not usually caught during the year. The occasional hunting usually only catches large individuals, which make room for smaller ones, so the population multiplies even faster," Tomáš pointed out. The crayfish themselves therefore help with regulation, much like predatory fish, for example, zander are deliberately introduced into ponds.
If the crayfish multiply uncontrollably, they create a focal population. They get stressed and tend to go to another watercourse, or they are inadvertently relocated by fishermen when the crayfish become entangled in their nets along with the fish.
"Our goal is not to wipe out the signal crayfish, but to prevent them from interacting with river crayfish and other crayfish populations. If we wanted to kill it off completely, the pond would have to be lime-lined and left unreleased for up to two years," Tomáš remarked, adding quite frankly:
"Nature would normally deal with invasive species on its own, but let's face it, man has deprived it of the ability to self-regulate. We live in an environment that is even officially called 'close to nature'." What mankind has ignited, conservationists are trying to extinguish. While the river crayfish is unlikely to go extinct, a rescue programme is already in the pipeline for the stone crayfish.
What's on the list is being destroyed!
The work of conservationists is sealed National Red Lists, which are the basis for the Annex to the Nature Conservation Act, made up of other lists of critically endangered, severely endangered or "just" endangered groups of animals and plants. "For us, it is also a guideline the EU list of invasive species. It applies within the EU and sets the strictest rules ever. It lists a total of 88 species that must not be transported, bred, marketed or released into the wild," emphasised Tomáš, as a member of the invasives commission.
"Last January, new legislation came into force. With it, we have adopted a European regulation to regulate all invasive species from the EU list, and at the same time we have to develop action plans against their spread and a strategy to deal with them in the context of our region," Tomáš recorded the query of the chefs who came to him with a clear intention: to link gastronomy with conservationists.
Awareness as part of the menu
"We freeze the crayfish we catch and dispose of them after some time. We haven't really looked into it yet, but it would make sense, if the crayfish biomass was taken to restaurants instead of the rendering plant. Moreover, gastronomy moves the Czech nation and can often educate the public better than scientific institutions," Tomáš commented on the cooperation and outlined the risks associated with the arrival of the signal crayfish on the menu:
"We have to take into account that some people may decide to catch their own crayfish or, heaven forbid, keep them at home in their pond. There is also the risk that they will fail to observe hygiene measures and spread crayfish spores into nearby watercourses."
On thin ice, we need to skate together, and send out education from institutions and kitchens. "We have no intention of making signal crayfish a regular menu item. We want to present it as an exceptional seasonal item and through food, revive a tradition that has disappeared, opening up the topic of invasive species," responded creative chef František Skopec. He has recently contacted other experts and is currently looking for a way to legislation to allow the processing of signal crayfish in restaurants.
The European gastronomy scene is already familiar with invasive species. For example, the invasive menu from London's restaurant SILOwhere they dared to serve the ash squirrel, or the Berlin project Holycrab with street food and products from red crayfish, wild oysters and river crabs. Both concepts represent relatively young concept of "invasiorism" that promotes the consumption of invasive species and culinary conservation.
An exception for an exception
"There is no mention in the law that signal crayfish may not be used in kitchens, yet we probably have to go the path of exceptions. I can imagine that we would hunt the crayfish under strict conditions, in a secret location and under the supervision of the Ministry of the Environment, but it is hard to know how many steps will lead to the goal," says Tomáš, with whose permission we tasted fresh crayfish cooked with vegetables and spices, on their own, and with crayfish sauce.
"The signal crayfish is the tastiest in my opinion, it resembles lobster. Moreover, it has the biggest claws of all crayfish. The red crayfish would also be considered, which hasn't appeared here yet. However, they found it in a stream in Veľká Fatra in spring," says Tomáš. And he revealed that he would like to write a cookbook in time.
Nightingales and winged warblers
Legislation seems to be easier on cooking with invasive fish species, which include the stone moroko, Prussian carp, Chinese sleeper or round goby. The latter travels along the Elbe River, through which striped crayfish and Chinese crabs have also arrived. But chefs are also interested in invasive mussels, such as the Asian corbicula and the multi-faceted mussel.
"It's a bit easier to collect mussels. With crayfish, you have to get the location right and they are often caught overnight, whereas mussels can be farmed. You place material in the water that the shells attach to and after about two months you 'harvest' them," Tomáš advised, turning his attention to the plant kingdom. The Czech borders were crossed without invitation by Himalayan balsam, Giant hogweed or the asparagus-like Japanese knotweed.
"An invasive species is one that is demonstrably harmful to nature and its biodiversity and ultimately to humans. Of course, there is also the question of when an animal or plant loses the invasive label and becomes domesticated. This also happens," Tomáš reminded us of the constant change and took the last question:
"Invasion of animals and plants is unavoidable in the future. It is simply a natural consequence of increased human mobility and our long-term behaviour, which unfortunately often resembles what invasive species are doing to the planet."
Something more:
The EU list of invasive species includes around 20 non-native animals and plants that currently inhabit the Czech Republic. These include plants such as the tree of heaven, common milkweed, giant hogweed, as well as the black bullhead, the red-eared slider and the egyptian goose, the northern raccoon, nutria and the river muskrat.
Crayfish have their main season in summer. Cooking School author Marie B. Svobodová used to buy them when wheat was in bloom. Today, they are ordered to Czech restaurants from abroad, from Germany, Spain or China, for example. When cooked, they are frozen to a temperature of around -30 °C even with the seagull fund. In particular, the signal crayfish can be caught in this country from April until the ponds are fished out, which falls in October or November.
The crayfish belong to on the table of rich and poor alike, until the middle of the 19th century, first weakened by industry and heavily polluted water, and later by the crayfish plague. The Czech crayfish industry was shaken by the regulation on the protection of native European crayfish in the 1930s. It concerned the river crayfish, the mud crayfish and the stone crayfish. Fishermen were required to have a fishing licence and a catch limit was set for male and female crayfish. The catch had to be at least 12 cm long.
Warning. Please do not attempt to search for or catch any species of crayfish. If you come across a signal crayfish, please contact the AOPK. On their website you will find instructionson what to do if you find one, and also the latest news on the presence of invasive species.
Source: AOPK ČR, Nature Conservation Forum
