Catfish released in 1974 become Spain’s ecological time bomb
The Wels catfish, introduced to Spain's Ebro River in 1974 for sport fishing, has become an invasive ecological threat. The species is now a dominant predator that is negatively impacting native fish populations and is considered impossible to eradicate.
Why it matters
It serves as a cautionary tale regarding the long-term ecological consequences of introducing non-native species into new environments.
German biologist and recreational fisherman Roland Lorkowsky released thousands of juvenile Wels catfish into Spain's Ebro River in 1974. His goal was simple and positive: to create a world-class sport fishery by introducing one of Europe's biggest freshwater fish. But today, the Wels catfish has become one of the dominant predators in many Spanish waterways. While they swim as the ultimate trophy catch for the sport fishermen, for conservationists these swimmers pose an ecological threat.Europe's freshwater kingThe Wels catfish is the largest freshwater fish native to Europe. It can grow to more than 8 feet (2.5 meters) in length, with exceptional individuals reportedly exceeding 9 feet and weighing more than 440 pounds (200 kilograms).
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