U-M study finds Asian carp could survive in larger areas of Lake Michigan than previously thought

Posted at 11:08 AM, Aug 12, 2019
and last updated 2019-08-12 11:08:21-04

ANN ARBOR, Mich. (WXYZ) — A new study from the University of Michigan found that Asian carp are capable of surviving and growing in larger areas of Lake Michigan than scientists previously believed. The modeling study from U of M researchers and their colleagues found that the Asian carp also present a high risk of becoming established.

According to the university, previous studies suggested that low food levels in the lake could be a barrier to the establishment of bighead and silver carp, two of the Asian carp species of greatest concern for the Great Lakes.

But, they found that the earlier studies didn't consider the fact that both carp could feed on a wide variety of diets, including dead organic matter, which can come from the countless quagga and zebra mussels at the bottom of the lake.

The model from the study showed the entire extent of Lake Michigan contains suitable bighead carp habitats somewhere in the water column. Silver carp were confined to nearshore areas.

"Subsurface habitat and the fishes' diet flexibility were not evaluated in previous studies, and our findings indicate that these considerations had a noticeable effect on our suitability assessment," the study's lead author, Peter Alsip said. "Lake Michigan's low supply of plankton may not be as strong a barrier as previously thought."

The study also found that:

  • "Allowing the fish to feed on the broadest possible diet (phytoplankton, zooplankton and detritus) throughout the water column resulted in suitable habitat volumes that were 4.6 times greater than the narrowest diet (phytoplankton only) for bighead carp and 2.3 times greater for silver carp."
  • "While the extent of high-quality Asian carp habitat across Lake Michigan is relatively small, the risk of localized establishment events is high near river mouths and in nutrient-rich parts of Green Bay. The team's model found suitable year-round habitat (which other models suggest is capable of supporting spawning and egg development) near the mouths of several rivers, including the Milwaukee and St. Joseph."
  • "Maps generated by the team's model identified Asian carp establishment hot spots and the potential for cross-lake migration corridors "that may facilitate and accelerate lake-wide movements," the authors wrote. Those maps could aid surveillance efforts by identifying areas to which bighead and silver carp might spread upon entering the lake."
  • "The relatively plankton-rich "deep chlorophyll layer" that forms each summer in offshore Lake Michigan waters is capable of supporting bighead carp growth. Previous carp studies did not evaluate growth potential in this layer, which forms at an average depth of about 100 feet."

To read more on the study, click here.