The Fish, and What Is Coming
Almost everything about the fish of Lake Champlain runs through one parasite. The sea lamprey arrived, the salmon and the lake trout collapsed, and since 1990 the fishery has been managed by killing lamprey larvae in the tributaries. It worked: lake trout stocking ended in 2025 because the population no longer needs it. Now a second animal is on its way, by two routes at once, and the two are monitored separately.
Two approaches, and the nearer one is in the north
The response, as it stands
Wounds per hundred fish
Lamprey control is measured by counting wounds on the fish that survive. Each species has a management objective, and the program is judged against it every year. The objectives are few enough to print in full:
Wounding rate is the number this fishery is managed against, and there is no published year-by-year record of it. It is a figure in each annual report — a picture, redrawn every year — with the values named in the text only for the year in hand and sometimes the one before. Those are the points above. The gaps are not missing data; they are data that has only ever been published as a chart. Tracing a curve off that image and calling it a series would be inventing numbers, so the space is left empty.
The fish lift at Winooski One
Ninety-nine fish, give or take a hundred and seventy
The lake sturgeon is the one fish here whose story is not mainly about lamprey. It was endangered before the lamprey program began and it is endangered now. What has changed is that the sturgeon are now counted — and the counts come with intervals wide enough that the interval is the finding.
What a fish of a given length carries
Vermont has sampled Lake Champlain fish for mercury eight times since 1987, and the 2019 survey pulled every one of those studies together with six hundred fish of its own. The Basin Program publishes the result as figures; the numbers behind them are here.
These are not averages, and an average would mislead. A big fish carries more mercury than a small one of the same species, so the mean of a catch measures the netting as much as it measures the lake. Each study fitted mercury against length and reported what a fish of a named standard length would carry — a fourteen-inch smallmouth, a twenty-inch walleye — and those fitted values are what is plotted. It is the only way these eight studies can be set beside each other at all.