Netting salmon to save them

Biologists are tracking reintroduced salmon to restore wild runs on Champlain tributaries

By Ry Rivard

It’s hard not to think of it from the salmon’s perspective.

They come into the Boquet River looking for a quiet place to breed and nest after several years in the rowdy waters of Lake Champlain. As they round a bend to swim through the town of Willsboro, with leaves overhead changing colors in early October, they get stuck in a net. The next morning, they’re pulled from the water, anesthetized and suddenly two new things are sticking out of their body.

If they’re not trucked several miles up the road to the calm waters ideal for them to nest, then they’re released right back in Willsboro near a sign that, if they could walk up the bank and read English, would explain what just happened to them.

The sign, titled “Things You May See On A Salmon,” was put up by the U.S. Fish and Wildlife Service. On it are two photos of the things that biologists have inserted into the fish to study and improve the 50-year push of getting wild salmon back in Lake Champlain.

One thing is a yellow tag manufactured by a Seattle company that has a unique number on it for anglers to use if they catch this fish and want to report what they’ve found to the Fish and Wildlife Service.

The other thing is a deeper implant, a radio tag sewn into the salmon, with its wire antenna sticking out past the surgical wound.

If all this seems rather odd, it’s because we sometimes take fish out of water to save them.

The tags are part of a study led by the Fish and Wildlife Services’ Jonah Withers. (We’ll explore the efforts to restore salmon to the Boquet River more in an upcoming article this weekend.)

The Fish and Wildlife Service wants to track about 60 salmon as they move through the Boquet to figure out how good they are at getting upstream and spawning.

Part of the study means that 30 tagged salmon are left in Willsboro once they’ve been caught and tagged. These fish will still have to swim past a small waterfall known as the cascades before they can reach spots suitable for nesting. The other 30 salmon are trucked past the cascades, essentially getting a lift to near the finish line.

The question is whether one group of salmon will do better than the other and why.

So far, after years of stocking Lake Champlain with millions of hatchery-bred fish over the past several decades, there have been just a handful of times when researchers can be sure that any of these salmon have had any babies.

The real wild salmon, the ones native to Lake Champlain and 10 of its tributaries, were wiped out rather quickly after European settlers took to the region and started fishing, polluting and damming. By the mid-1800s, no one could find a salmon in Lake Champlain.

Now, like in all places where people are trying to undo the mistakes of the past, there is a high degree of intervention in the lives of fish and ignorant plundering has been replaced with laborious probing.

Though there were several hatcheries around the lake going back over a century, the first sustained effort to restore salmon didn’t begin until the early 1970s when officials from Vermont, New York and the federal government got together and started building a series of hatcheries in the region to breed salmon, using fish that Vermont officials got from Maine’s Sebago Lake.

The restocking quickly ran into major obstacles, though, because with the rebound in salmon came a rebound in lamprey. These parasitic eel-like fish attach themselves to salmon and suck their blood.

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A series of experiments in the Great Lakes, which was having similar problems, discovered chemicals now known as lampricides that kill lamprey larvae and little else. Now, lampricides are regularly applied in waters throughout the Champlain Valley and in the Adirondack tributaries that feed the lake.

Other obstacles remain, most visibly dams that block salmon from entering the Saranac River in New York and the Winooski River in Vermont.

Beneath the surface, though, are other puzzles, some as nebulous as what motivates a salmon to decide where to nest.

If salmon are raised in a hatchery and then dumped a river, are they less likely to call the river home than if they were born there? That’s one reason the federal government is for the first time stocking ready-to-mate hatchery fish in the Boquet this year, in hopes that more salmon will be born in the river. In the past, the river was stocked only with salmon that were born or partly raised in hatcheries and hatchery pools known as raceways.

“Hatchery fish have grown in a raceway their entire life, so they probably are not going to be nearly as efficient at surviving in the river or digging redds,” said Bill Ardren, a senior fish biologist at the Fish and Wildlife Service. Salmon nests are known as redds.

Another hidden problem is a vicious cycle involving an invasive herring known as the alewife. About 20 years ago, alewives were found in the lake near the Canadian border and have since spread across the lake, becoming one of the main sources of food for salmon.

But alewives have an enzyme in them that kills vitamin B in other fish that eat them. As a result, salmon now stuck eating alewives are ending up with a vitamin deficiency.

So officials are now trying to deal with that, too.

There may be hope in sight. Biologists have found some salmon in Lake Champlain that are more tolerant of vitamin decencies than others. So, soon, the program may be using those to breed salmon that can withstand the ever-changing lake.