Invasive, parasitic fish in Great Lakes thrived during COVID-19
COLUMBUS, Ohio (WCMH) — A study has revealed the effect of the COVID-19 pandemic on an invasive parasitic fish that wounds and kills Great Lakes native species like lake trout, whitefish, ciscoes, and walleye.
According to the Great Lakes Fishery Commission, the sea lamprey feeds on the blood and fluids of other fish by attaching itself with its sharp tongue. The aquatic pest has been wreaking havoc since entering the region from the Atlantic Ocean more than 150 years ago. Experts note that one sea lamprey can kill up to 40 pounds of fish in its parasitic stage. At its most prolific nearly 75 years ago, almost 2.5 million sea lampreys killed 100 million pounds of fish annually.
In the 1950s, a sea lamprey control program began, which led to populations plummeting to about “10% of their historic highs.” However, COVID-era travel restrictions impeded efforts to reduce or eliminate the creature.
Study authors, who published their findings in the journal “Fisheries,” sought to discover if sea lampreys still “posed a threat to Great Lakes fisheries” or if “sea lamprey control [was] still necessary to suppress their populations.”
“When life gives you lemons, make lemonade,” said Dr. Nick Johnson, a research ecologist with the U.S. Geological Survey and a co-author on the study. “When the COVID-19 pandemic significantly reduced sea lamprey control for two years, our research team made the most of the situation by using it as an unplanned experiment to learn valuable information — nearly impossible to obtain otherwise — about the current impact of control on sea lamprey populations.”
The team of 15 scientists found that reductions in applying lampricide, a “pesticide highly selective to lampreys,” in 2020 and 2021 allowed the organism's population to explode.
“Like a coiled spring, sea lamprey populations bounced back quickly when control was relaxed,” said Dr. Ben Marcy-Quay, a fish biologist with the U.S. Geological Survey and the lead author of the study. “Wounding on Chinook and coho salmon, specifically, increased over 10-fold. Our findings support observations by the fishing public and fishery managers of fish riddled with sea lamprey wounds, some containing three or more wounds per fish.”
The Great Lakes Fishery Commission asserted that study results confirm that continued vigilance against the sea lamprey is necessary to protect “Great Lakes fish and the valuable fisheries they support.”