Wild-born lake trout, long a rare catch, thrive in changed waters
By Ry Rivard
Long after wild salmon and lake trout disappeared from Lake Champlain, government officials around the lake began to dump hundreds of thousands of fish into the lake each year.
Most died naturally. Others were caught by anglers. Few, if any, reproduced. If there were going to be trout or salmon, it seemed, they were going to come from one of the government-run hatcheries near the lake in Vermont or New York.
Now, though, nature seems to be taking over, at least a bit.
In 2015, Ellen Marsden, a researcher from the University of Vermont, went out to count how many trout in the lake were hatchery-bred, and how many were born wild in the lake.
Past samples showed all the trout had clipped fins, the sign they were reared by humans.
This time, something had changed. Nets cast from the research vessel Melosira brought up lake trout with unclipped fins.
“There were happy dances all over the deck,” Marsden said. “I can tell you, it was the most amazing thing.”
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The good news continued. In the years since, Marsden’s samples show more and more of the trout in the lake are wild.
For the group of people used to operating the fish-stocking programs, this is a strange new fact.
For years, officials from the hatcheries around the lake knew roughly how to count the number of fish in the lake—they had put them there. Now lake trout are breeding in the wild, making their current numbers harder to fathom.
Hatchery officials who once worried they weren’t stocking enough trout now have to worry they’ll stock too many. There are now perhaps 100,000 or 200,000 trout in the lake. Too many trout in one lake could collapse the food chain, if too many eat too much.
“Wild fish is the wild card,” said Steve Hurst, the head of New York’s fisheries bureau.
Hurst is one in a line of government officials who have been restoring the lake, fish by fish, for 50 years. The modern stocking effort began in the 1970s, when officials from Vermont, New York and the federal Fish and Wildlife Service came together to start a massive hatchery program. By then, salmon had been gone since the mid-1800s, and trout since about 1900.
New trout fishing regulations took effect April 1
Now, for the first time because of good news, they expect to put one-third fewer trout into the lake. That means New York will stop stocking the lake with the 27,000 or so trout it usually does.
The changes don’t affect stocking of other fish in other waters.
There are some clear reasons for trout’s rebound. One is that people seem to be winning the fight against lamprey, a snake-looking fish that attaches itself to the sides of other fish and sucks their blood. In the 1990s, lamprey were killing half the trout in the lake. Lamprey wounds are still common, but officials believe they have the problem under control thanks to an ingenious pesticide that kills lamprey and little else.
But that isn’t the only thing. Trout are doing well compared to salmon, a fish whose wild return has been stymied by dams around the lake that keep salmon from returning to their ancestral spawning grounds.
Lake trout, by contrast, are happy to mate in the lake. And, in recent years, they seem to be having a good time, because Marsden’s samples are showing trout are well fed and sexually active.
Key information is missing about why, but Marsden is beginning to work on some theories that make some of the lake’s usual villains—invasive species, namely alewives and zebra mussels—into more complicated figures that may be helping the trout.
“In odd, indirect ways, it’s possible,” Marsden said, though there is much more to study.
About 20 years ago, invasive herring known as alewives were found in Champlain near the Canadian border, and they have since spread across the lake. While eating too many alewives can leave fish with a vitamin deficiency, the larval alewives might be good enough for young trout.
Zebra mussels, clingy bivalves originally from the Black and Caspian seas, can clog intake pipes, mess up boats and muscle out native species. But they may also be taking over near-shore habitat where stocked trout tended to congregate.
When mussels cover up the usual spots, trout may be heading elsewhere to breed. Perhaps out there, the trout can do better. This is something Marsden compares to someone who goes to a new bar and meets new people.
Whatever is happening, there’s years of research showing it may be a permanent change.
“This isn’t just a flash in the pan,” Marsden said.
And now it’s humans who have to adapt.
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