Asian Carp Could Be Spawning In More Rivers Than Previously Thought

Asian carp might be able to spawn in shorter stretches of Great Lakes tributaries than previously thought.

If the invasive Asian carp gets into the Great Lakes in significant numbers, it’s believed the big fish wouldn’t be able to spawn in the lakes – they would have to do so in fast-moving rivers leading into the big waters. A study by the U.S. Geological Survey says two species of Asian carp — bighead and silver — would be able to spawn in river stretches as short as 16 miles, instead of the 62 miles observed in the southern United States or Asia.

Researcher and hydrologist Elizabeth Murphy says the study collected data on egg development, water quality, temperature, and river flow.

“The river will carry the eggs, keep them in suspension, and they’ll develop fast enough that they would hatch before they would reach an area where they would settle out. We determined they would have sufficient time to develop hatching in just that 16-mile reach.”

Murphy says the findings show the carp could spawn in more rivers than previously thought, though perhaps not every year.

“It depends on the velocity of the river at that particular time – depending on how much rain we get – and also the temperature of the water.”

The study looked at two Lake Erie tributaries and two Lake Michigan ones. The Milwaukee River was chosen because of its relative proximity to Chicago-area waterways, which scientists fear could be the route Asian carp take to get from the Mississippi River system into the Great Lakes.

The message for governments trying to keep the big carp from establishing lake populations? Says Murphy: “Well, I’m afraid the message is we’ve made their job a little harder.”