From Interlochen Public Radio:
The number of sea lamprey in Lake Michigan shot up again last year. The fight against the parasite is 50 years old, but lately the lamprey has been getting the upper hand. Its population has been on the rise for a decade, and is now estimated to be about 50 percent higher than fishery biologists would like.

A new study estimates there are about 90,000 adult lamprey in Lake Michigan. Lake managers would like there to be less than 60,000. Still it’s better than 2007, when the number was close to three times the target.

Lamprey are the oldest invasive species in the Great Lakes. The parasite attaches to large fish such as salmon and lake trout and is one of the main reasons trout are doing so poorly in Lake Michigan. Read more.