Airdate: Dec 17, 1997
Scientist: Melanie Stiassny
LAKE VICTORIA: Nile Perch
The voracious appetite of the Nile Perch, a species introduced into Lake Victoria, has all but extinguished the Lake’s underwater life.
Imagine what it would be like trying to survive in your neighborhood if a pack of man-eating tigers were suddenly released there. Well, that's pretty close to what's happened to the fish in east Africa's Lake Victoria. I'm Jim Metzner, and this is the Pulse of the Planet, presented by the American Museum of Natural History.
"A major impact on the lake has been the introduction of species that don't come from the lake -- the introduction of exotic species. In particular, one fish has been introduced into Lake Victoria that has wrought havoc on the whole ecosystem, and that's the Nile Perch."
Melanie Stiassny chairs the American Museum of Natural History's Ichthyology Department. She tells us that the people who live near Lake Victoria -- the largest tropical lake in the world -- depend upon its fish as a source of food. Over the years, though, the lake has been over-fished, and to stock the lake, new species of fish, like the Nile Perch, were introduced without thought for the consequences.
"The Nile Perch has never naturally occurred in the lake. So, all of the other fishes and there are hundreds of species of fishes that once lived in Lake Victoria and were found nowhere else in the world. All of those fishes of Lake Victoria are not used to a big predator like the Nile Perch."
The voracious appetite of the Nile Perch, combined with overfishing all but eliminated the many species of fish that once thrived in Lake Victoria.
"The people that introduced the Nile Perch didn't introduce the Perch to be mean or wicked. They introduced the Perch because they thought it would be a good way of augmenting the fishery. What's happened in Lake Victoria really just points out if we don't really understand how a system's put together, we can have no idea what the effect of one of these introductions is going to be."
Now you might wonder, if all the other fish are gone, what's keeping the Nile Perch alive? We'll answer that question in our next program. Pulse of the Planet is presented by the American Museum of Natural History. I'm Jim Metzner.