The sea lamprey population in Lake Superior has decreased over the past several years, but remains above target levels.
A report released this week by the Great Lakes Fishery Commission notes that targeted treatments performed in 2016 seem to have reduced the numbers from near-record highs recorded two years ago.
Additional targeted treatments were performed this past summer. The results of those will not be discernible until 2021.
Typical treatment involves introducing lampricides into tributary waters to kill lamprey larvae, which burrow in the beds of rivers and streams for several years before migrating into the lake.
As for the other Great Lakes, levels are near historic lows in Lakes Michigan, Huron and Ontario, but are above targets in Lake Erie.
See the full report here.