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U.S. Geological Survey - Great Lakes Science Center

Coming Full Circle: Returning Atlantic Salmon to Lake Ontario

1 USGS Atlantic Salmon

“Lake Ontario and certain lesser lakes tributary to the St. Lawrence River represented the most striking worldwide example of freshwater colonization by the Atlantic salmon.” (Webster 1982)

Atlantic salmon – one of the most prized food and game fish in the world – have returned to Lake Ontario. Although Atlantic salmon are best known as a species native to the Atlantic Ocean, the salmon are also native to Lake Ontario, where they once swam in great numbers. Historically, the Lake Ontario population of Atlantic salmon represented the largest freshwater population of salmon in the world. Indeed, the salmon in Lake Ontario were once so abundant that stories still circulate today of horses fording streams by walking almost literally on the backs of spawning salmon. But the days of massive spawning runs disappeared quickly in Lake Ontario during the 1800s, when a combination of overfishing, pollution, and habitat alteration (particularly the damming of Lake Ontario tributaries) disrupted spawning habitat. The result was an extirpation of Atlantic salmon from Lake Ontario for over a century.

But starting in the 1970s, New York State’s Department of Environmental Conservation and the Ontario Ministry of Natural Resources, in partnership with the St. Regis Mohawk Tribe, have been reintroducing Atlantic salmon into Lake Ontario and St. Lawrence River tributaries. In the early 2000s, the USGS Great Lakes Science Center (GLSC) joined the effort through work at the Tunison Laboratory of Aquatic Science, a field station of the GLSC located in Cortland, NY.

Part of the GLSC’s mission is to provide the scientific information necessary for restoring native species to the Great Lakes. Scientists at the Tunison lab developed innovative Atlantic salmon rearing techniques and have evaluated multiple salmon strains to determine each strain’s suitability for restoration. In addition, scientists have identified salmon release locations with the highest probability for success of capturing returning adult salmon, a critical part of establishing a Lake Ontario egg source to perpetuate the restoration effort.

These efforts are currently focused in three geographic areas: eastern Lake Ontario tributaries, St. Lawrence River tributaries, and the Oswego River. The primary focus of efforts by the GLSC is the eastern Lake Ontario tributaries, particularly the Salmon River, which was historically one of the most important spawning streams for Atlantic Salmon in the lake, although the GLSC is also involved in restoration efforts in the St. Lawrence River tributaries.

Work on Atlantic salmon restoration at the Tunison lab focuses around three Lake Ontario fish community objectives set by the Lake Ontario Committee: 1) increase natural reproduction of Atlantic salmon in the Salmon River system; 2) increase returns of mature Atlantic salmon to Beaverdam Brook, a tributary of the Salmon River; and 3) increase recreational catches of Atlantic salmon in the Salmon River system. The work is also guided by a Great Lakes Restoration Initiative objective to develop a Lake Ontario source of Atlantic salmon eggs by releasing young salmon at sites where adult salmon can be captured later for use as broodstock (i.e., individuals used for breeding).

To increase natural reproduction of Atlantic salmon in the Salmon River, mature adult salmon are collected at a weir on Beaverdam Brook and used as broodstock. The adult salmon are brought to the Tunison lab, where their eggs are collected, fertilized, and hatched, after which the young salmon are released into the wild at various life stages. A critical feature of the Tunison lab that makes this work possible is a UV treatment facility which provides state-of-the-art capabilities for holding eggs from wild-captured adults and raising the fish for release. The UV treatment prevents any diseases or organisms from being released into the local watershed of the Tunison lab.

Release of salmon raised at the Tunison lab into the Salmon River has focused on two life stages: fall fingerlings (approximately 6 month old salmon) and yearling smolts (approximately one year old salmon). Starting in 2013, the GLSC raised and released about 60,000 fall fingerlings in the Salmon River, and the number has risen in the years since to about 80,000 fall fingerlings released in 2016. About 10,000 yearling smolts were released in 2012, and similarly the number has grown through the years to about 26,000 in 2016. Targets for releases during 2017 include 90,000 fall fingerlings and 20,000 yearling smolts.

Of course, releasing young salmon is only the first step of the larger effort to restore Atlantic salmon in Lake Ontario. For restoration efforts to be considered successful, GLSC biologists also need to know whether any of the released fish return to spawn as adults, and whether there are naturally produced young (fry) in the river. The answer to both of these questions is yes.

During 2013, four adult Atlantic salmon returned to Beaverdam Brook, eleven adults returned during 2014, and twenty-two adults returned during 2016. Although the early numbers of salmon returns are small, success stories have to start someplace. The GLSC biologists know that there are other adult salmon in the river that are not reaching the collection weir in Beaverdam Brook. Many of these salmon support fishery harvests in the main stem of the Salmon River – in 2015 alone, anglers harvested over 300 Atlantic salmon from the river. Collections of naturally produced fry are also good news for restoration efforts. In 2009-2011, and again in 2013, wild fry were collected. With as many as forty fry collected during a single year, early signs show promise for the return of Atlantic salmon to Lake Ontario.

Lead Photo: A subyearling Atlantic salmon collected during 2009. This fish has special status as the first evidence of natural reproduction of Atlantic salmon in Lake Ontario in over a century.

Photo Credit: 
USGS

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