Lake Ontario once held the largest freshwater Atlantic salmon population in the world.
And then came a flood of anglers, habitat-destroying development and dams. The mix proved deadly as Lake Ontario Atlantic salmon went extinct about a century ago.
Now, U.S. and Canadian scientists are reviving the formerly thriving fishery.
Stocking, weeding out diseases
“We stocked 65,000 fingerlings in Lake Ontario tributaries in September,” said Jim Johnson, eastern branch chief for the United States Geological Survey’s Great Lakes Science Center in Cortland, N.Y.
The center received Atlantic salmon eggs, from Vermont and Maine last year. The main strain used, Atlantic salmon from Sebago Lake, Maine, was chosen because it’s performing well in New York’s inland lakes, Johnson said.
Development and dams are a major reason the Atlantic salmon went extinct. In the fall, four- or five-year-old adult salmon return to spawn. Unlike other salmon species that spawn once and die, Atlantic salmon can spawn for years.
The center will collect returning fish to aid spawning.
“There could be disease issues and we want to weed those out,” Johnson said.
It takes approximately six weeks to see if the fish have a disease, Johnson said. For healthy spawning researchers need to make sure diseased fish don’t contaminate local waters.
Fish are held in wells that discharge into a local stream. The center treats the outgoing water with ultraviolet light to kill germs and prevent their spread.
Not the first try for New York
New York has unsuccessfully tried to reintroduce Atlantic salmon for decades, said Steve LaPan, a Lake Ontario unit leader for the state’s Department of Environmental Conservation. But this time around there is better research to inform the efforts.
“Jim’s (Johnson) research will tell us what strains will perform the best … we’ve tried many different strains in the past,” LaPan said.
One trait they’re looking for is the ability to tolerate a vitamin B deficiency. Alewives, a common snack for trout and salmon, have bacteria that eat away at a fish’s vitamin B supply.
It is unknown if the Sebago Lake salmon strain better tolerates a vitamin B deficiency, LaPan said. But it has the advantage, returning to tributaries to spawn instead of fleeing down the St. Lawrence River like other strains.
Help from the north
The same fish are also getting a boost from the Canadians.
The Ontario Federation of Anglers and Hunters and the Ontario Ministry of Natural Resources have stocked approximately 2.7 million young salmon since 2006.
Efforts from the Ontario and the New York folks are coordinated, said Chris Robinson, Atlantic salmon program coordinator for the Ontario Federation of Anglers and Hunters.
Stocking is only one part of what needs to be done, Robinson said.
“We’ve completed 130 stream restoration projects in the six years we’ve been around,” he said. “Not only does it restore
habitat, but by using a large volunteer base to do the work, we’re teaching people how to improve and protect habitat.”
Atlantic salmon are coming “back to a world that’s totally different than the one when they were wiped out,” Robinson said. The group plants fish in cold water streams with rock and gravel bottoms well-suited for salmon.
Salmon use rocks and gravel to nest and hatch eggs and for cover and habitat. In Ontario streams, rocks were often covered by sediment from erosion, Robinson said, so stream restoration often means restoring rock and gravel bottoms. They also restore riverbanks to prevent erosion and add places for animals to cross the river so they don’t trounce fish hangouts.
“We have a lot of high quality habitat in the streams already,” LaPan said. “Our first priority is to get the fish population rehabilitated.”
Johnson believes Atlantic salmon will be successful in Lake Ontario this time around since there are now fishing regulations and most dams that prevented spawning on the U.S. side have been removed.
The ultimate goal is a self-sustaining population, which, according to the Ontario Ministry of Natural Resources, will take about 15-20 years.
Featured image: zalgon (Flickr)