The Great Lakes News Collaborative includes Bridge Michigan; Circle of Blue; Great Lakes Now at Detroit Public Television; Michigan Public, Michigan’s NPR News Leader; and The Narwhal who work together to bring audiences news and information about the impact of climate change, pollution, and aging infrastructure on the Great Lakes and drinking water. This independent journalism is supported by the Charles Stewart Mott Foundation.
It’s springtime, which means migration and spawning for many Lake Ontario fish — and a good time to share the fascinating story of how many salmon and trout came to live in this Great Lake in the first place. Brook trout and Atlantic salmon are native to the lake, but in 1873, the federal government began stocking it with non-native salmonids — a large family of ray-finned, carnivorous fish — starting with chinook salmon. Coho salmon, steelhead, and brown trout soon followed.
They didn’t thrive at first, though. Dams impeded spawning migrations, pollution from lumber mills and tanneries degraded water quality and clearing forests for urbanization and agriculture warmed waters. This limited natural reproduction of stocked non-native species. It was also devastating for native species: combined with overharvesting, environmental harm caused the decline of some, like brook trout, and the wholesale loss of others, like Atlantic salmon.
Stocking resumed in the late 1960s as environmental awareness increased and stream quality improved, culminating in Ontario, Quebec and a number of U.S. states signing the Great Lakes Water Quality Agreement in 1972. By the 2000s all introduced species were reproducing naturally. Now, most of these fish are from the wild, not hatchery-raised — over half the lake’s chinook and coho salmon are wild, and some streams have entirely wild runs. Last fall, approximately 20,000 wild chinook and coho salmon, along with some wild brown trout and steelhead, returned to the Ganaraska River in Northumberland County to spawn. While these fish aren’t native to Lake Ontario, they’re now an important part of the ecosystem, bringing lake-derived nutrients upstream.
The fact that these fish are wild-reproducing and self-sustaining is an incredible success story. But it’s often overlooked by anglers and the public and ignored by government agencies on both sides of the border. Many streams could support even more wild reproduction, but agency policies favour putting money towards stocking non-native fish for anglers instead of habitat restoration that would benefit struggling native fish populations and the whole ecosystem. Ontario and New York state’s shared Fish Community Objectives for Lake Ontario openly acknowledges that prioritizing food for chinook could hurt native fish: chinook salmon’s preferred food is non-native alewife, but eating alewife can reduce fertility in native salmonids.
Click here to read more greatlakesnow.org
Photo Credit: pexels-ron-lach
Categories: Michigan, General