A small family-run fishery in Berlin's Spandau district was granted permission to catch the red crustaceans for human consumption last week.

Over 1,600 crayfish found themselves in fishing nets in the first few days alone, said Derk Ehlert, a wild fauna expert from the Senate's environmental department in Berlin.

After health officials gave the all-clear about a week ago, fishermen jumped at the opportunity and immediately started catching them, intending to sell them to restaurants and private individuals.

“But we expect declining quantities over the course of the year,” Ehlert added.

Large populations of the red swamp Louisiana crayfish, which grow up to 15 centimetres in length and are originally from parts of the southern US and northern Mexico, came to the attention of visitors and locals in Berlin’s Tiergarten park in August.

They were spotted scuttling across streets and pathways and have since grown in significant numbers in lakes in and around the park.

Environmental authorities gave fishermen permission to catch the crayfish for a period lasting to the end of the year after assessing that they did not contain dangerous levels of toxins or heavy metals.

“No limits have been exceeded” with regard to pollutants, Ehlert said during examination of the animals.

But grabbing and catching one yourself is “prohibited,” the expert warned, as this would be considered poaching.

If you are able to get your hands on one of the crustaceans from the fishery, a traditional way of cooking them in the American south – where it’s considered a delicacy – is to place them live into a pot of boiling water seasoned with cayenne pepper, salt, lemon, garlic, onions and bay leaves.

Boil the crayfish for just under five minutes and let them stand covered for 5-20 minutes, depending on your preference. Then serve with sweetcorn and potatoes.