As heard on Outdoor Journal Radio

When the COVID-19 pandemic interrupted field operations across the Great Lakes region in 2020 and 2021, it inadvertently created an opportunity for one of the region’s most persistent invaders: the parasitic fish known as the sea lamprey. A multi-agency study published in 2025 by the U.S. Geological Survey (USGS) and its partners found that reductions in routine control efforts correlated with a sharp increase in lamprey abundance and associated fish wounding across the lakes.

What happened
During the pandemic, many regular stream treatments with lampricides, chemicals used to suppress lamprey larvae before they mature into parasitic adults, were delayed or scaled back. In one notable example in Lake Ontario, the adult sea lamprey population was estimated to have increased dramatically when control efforts dropped. In the same region, the rate of fish showing lamprey wounds (particularly on sport-fish such as Chinook and Coho salmon) increased more than tenfold.

Why this matters
The sea lamprey is a non-native parasitic fish in the Great Lakes basin that attaches to other fish, feeds on their blood and body fluids, and, in large numbers, can cause serious harm to commercial and recreational fisheries. For decades, the control program coordinated by the Great Lakes Fishery Commission (GLFC) and executed by US and Canadian agencies has been credited with reducing lamprey populations by about 90 % compared to pre-control levels. The new study, however, reinforces that consistent annual control is critical and that even short interruptions can lead to rapid resurgence of the invasive species.

What the data show
The USGS study used long-term lamprey abundance indicators, stream-treatment records, and fish-wound monitoring in Lake Ontario and other basins to assess the impact of relaxed control. The result showed that when treatment operations decreased, adult lamprey abundance rose substantially. While the relationship between abundance increase and Lake Trout wounding was weaker, the multi-species wounding metric for Lake Ontario clearly climbed in tandem with the control lapse.

Budget cuts and the DOGE effect
In addition to pandemic disruptions, the control program faced further strain due to budget and staffing cuts associated with the Department of Government Efficiency (DOGE), a newly-formed federal agency aimed at streamlining government operations. Reports indicate that DOGE mandated immediate termination of key personnel in the invasive species control unit, including 12–14 staff working on sea lamprey control in the U.S., raising concerns about the continuity of the program. Commentators argue that the staff reductions, hiring freezes and travel restrictions imposed under DOGE further weakened the capacity for timely stream treatments and monitoring, compounding the effect of the pandemic pause. Although some reversals and reinstatements of cuts occurred later, managers caution that the combination of the pandemic pause and funding/staffing disruptions has created a “stress test” for the lamprey control program, showing just how vulnerable it is to external slowdowns.

Implications going forward
Fishery managers warn that the surge in lamprey numbers will likely persist even as control efforts resume. In the words of GLFC officials, “if we take our foot off the gas, even for a short while, sea lamprey populations will increase rapidly and cause considerable damage to fish.” They emphasize that consistent annual stream treatments and monitoring remain essential to protect the multi-billion-dollar Great Lakes fishery, which supports both commercial and recreational interests. The pandemic-linked disruption, coupled with budget/staffing cuts, is now being framed as a cautionary tale: future breaks in control effort, whether due to pandemics, budget cuts, or access issues, may lead to similarly rapid rebounds in invasive species populations.