The Fisheries
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 invader, the round goby, 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 years in which the rate was published only as a chart and never as a number. 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
Winooski River spawning run, 2017: 99 fish, 95% interval 42–215
The lake sturgeon is the one fish on this page whose history 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.
Mercury in a fish of a standard length, by study
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 values at a standard length, not averages, because 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.