The wels catfish lays 25,000 eggs in one clutch. After three years, the young fish are ready to breed, and after another three years they typically grow to be a meter long. While the fish naturally spawns only once every 10 years, the summer temperatures in the Rhine apparently increase the capacity to breed each year. Still Lankau, the biologist, says he wouldn't call the fish a menace. "The wels catfish will not deprive itself of its own basic food source by eating up all the other fish," he says.
Catfish Replaces the Trout
The opinions of fishermen on the wels are diverse. Many are excited about the growing population and are upgrading their equipment -- in order to catch the wels catfish, you need an extremely heavy fishing rod and large pieces of bait. But many traditional fishermen hate the wels. As soon as it appears on the scene, populations of native species seem to drop.
Recently, another newcomer has emerged in the Rhine: The goby, hardly the size of a finger, was first found in the river in 2008 and has expanded similarly to the wels catfish. The Rhine Fishermen Society is calling it "one of the most dramatic changes in the Rhine fauna that has ever been documented." The wels catfish love gobies. The tiny creatures like hanging out on the riverbed, making easy prey for predator fish. Whether the goby is partially responsible for the wels catfish expansion is still unclear.
Gottfriend S. has been fishing for 40 years in the Sieg, a tributary of the Rhine in the western state of North Rhine-Westphalia. He shrugs as he points to an empty bucket. "You used to always find trout here, but the wels catfish is wiping everything out," he says. His fishermen's association this year got rid of all its closed seasons for catching the catfish, calling on its members to target the fish and not throw them back in the water. But that's not always easy. Gottfried S. recently had to call in the help of a local farmer to help an exhausted fisherman pull a giant wels catfish out of the water. They needed a tractor to get the job done.
Its enormous size makes the wels catfish an ideal candidate to fill up newspapers desperate for good stories in the notoriously slow summer news cycle. "Gigantic Fish Grabs 14-Year-Old in Swimming Lagoon" read one headline last August from the website of the magazine Focus. The youth's mother confirmed the incident over the phone: "The thing pulled her underwater, thank God she was able to get free." The girl's father sought revenge and tried to catch the fish himself. "My daughter could defend herself, but were an animal like this to grab hold of a child, it wouldn't stand a chance. These giant creatures have to go!"