“Cajun Crawfish Invading Africa” from National Geographic news via Africa Files:
It’s a far cry from Cajun country, but a U.S. crayfish used in Southern cooking is now eating its way across Africa, scientists say. Without any native predators to keep it in check, the Louisiana crayfish, also known as the red swamp crayfish, is gobbling up small freshwater fish, fish eggs, mollusks, crustaceans, and aquatic plants. The 6-inch-long (15-centimeter-long) invader is already widely distributed in lakes and other bodies of water throughout Kenya, as well as in Rwanda, Uganda, Egypt, Zambia, the Seychelles, Mauritius, and South Africa.
Conservationists are now concerned the crayfish will reach the East African lakes of Malawi, Tanganyika, and Victoria, which are home to hundreds—and probably thousands—of species found nowhere else. “By removing animals and plants from wetlands, [the crayfish] can upset the balance of ecosystems and reduce valuable ecosystem functions,” said Geoffrey Howard, global coordinator for invasive species for the Species Programme of the International Union for Conservation of Nature (IUCN).
Louisiana crayfish were first imported in the 1970s into Kenya and South Africa, where the species was grown in aquaculture operations. People bred the species in Kenya’s Lake Naivasha and sold the delicacy to Scandinavian buyers after that region’s native crayfish had been wiped out by disease. “They are rarely seen or recognized as a threat,” Howard said, “but they have certainly affected the fishery in Naivasha.” That’s because, “by eating fish eggs and fingerlings, [crayfish] can reduce the populations of fishable fish.” . . .
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