Urbanibalism

Crustacean canalbilism

Two exotic aquatic decapods have taken up residence in the posh precincts of Amsterdam’s canals and waterways: the American red swamp crayfish and the Chinese mitten crab. These ‘invasive species’ arrived to northern Europe through the food and pet trade and, more commonly, through crab or lobster larvae in ships’ ballast water. We constructed some traps and headed to the canals for some crustacean canalbilism.

The American swamp crayfish (Procambarus clarkii), endemic to the States (Louisianna), are bred for the aquarium and food trade. Since recent decades, these Louisianna crayfish have been inhabiting the Amsterdam estuary in abundance. The marshlands and brackish water channels of Amsterdam make a perfect abode. Yet this species appears to be threatening other native species of shell and crayfish, not only becuase of their voracious appetite for fish eggs and salamanders and their hyperactive burrowing which disturbs the canal or lakebeds, but also because the swamp crayfish is carrier of the crayfish plague — a fungus disease which the red swamp crayfish is immune to but it does infect other, native species of cray.

The Chinese mitten crab (Eriocheir sinensis) is indeed a crab with mits — its claws are covered with small tufts of brown fur like the fur muffs (hand warmers) . Like the swamp cray, the mittened crab is an colonizer of the ports of Amsterdam and Rotterdam among other (mostly northern) European cities. In London they’ve been spotted marching sideways onto high street, and even in swimming pools. Although considered an absolute delicacy in China, they are deemed a pest in this part of the world. Some entrepreneurial types are thinking of importing the unwanted crabs back to China to replenish China’s depleted stock.

To make use of this surplus of canal crustaceans, we’re now investigating how edible they actually are with the help of an aquatic toxicologist. It seems the waters in and around Amsterdam are relatively free of pollutant matter (this is a worry especially since the crustaceans especially Chinese crabs can easily tolerate and absorb heavy metals such as cadmium and mercury). City ecologist Martin Melchers and Amsterdam fisherman Piet Ruyter have been guidied us on a cray and crab catching expeditions throughout mid-April and early May as the crustaceans roused from their winterburrowing.