Fisheries biologists will be closely monitoring the Credit River in the years to come, following the surprising appearance of significant numbers of spawning Atlantic salmon in 2008 and 2009.
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| Fisheries biologists use electrofishing to monitor the Credit River for signs of Atlantic salmon. Photo: MNR-2007 COA-Jason Mortlock |
“We didn’t expect this response so early in the program,” says Marion Daniels, a Ministry of Natural Resources lake management biologist. “The salmon were stocked as fry only several years ago and the Credit’s fisheries habitat is still being rehabilitated.”
Daniels says until 2006, the Ministry and its partners were testing rehabilitation and stocking in many waterways flowing into Lake Ontario, trying to learn what might succeed in restoring Atlantic salmon in Lake Ontario and its tributaries.
The partners then released large numbers of fry (a total of 2.5 million to date) in three carefully chosen creeks: the Credit River in Mississauga, Duffins Creek in Durham Region and Cobourg Brook in Northumberland County. The hope was to kick-start spawning.
In 2008, only two years later, a pair of Atlantic salmon was observed spawning in the Credit. Other spawning salmon were also reported in 2009. The same year, at the Streetsville dam about 20 kilometres upstream from Lake Ontario, observers watched as dozens of salmon tried to move upstream. Volunteer anglers managed to catch 34 adult fish and release them above the dam.
“The numbers of fish might not seem impressive,” says Daniels, “but you have to consider that normally at least half the fry stocked don’t survive, and the Credit is not a wild country stream but an altered waterway struggling through a residential/industrial landscape in the GTA.”
Atlantic salmon thrive in clean, cold waters flowing fast over gravel streambeds. As an indicator species, their presence marks the health of an ecosystem. “The appearance of the salmon in 2008 and 2009 is very good news,” says Daniels.
This year and in coming years, Ministry biologists will be using electrofishing and the observations of a network of volunteers to find out how many salmon are navigating, growing and surviving in the Credit River, Duffins Creek and Cobourg Brook. Find out more at www.bringbackthesalmon.ca
Click here to view a map of the project area
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What is Electrofishing?
• Electrofishing involves putting a mild electric current into the water to temporarily immobilize fish, which are netted and held in a live well. Biologists then identify, measure and weigh the fish, collect scale and tissue samples from any Atlantic salmon caught, and then release the fish unharmed back into their home waters.
• Electrofishing also provides an opportunity to assess the populations of other species that are temporarily immobilized.
• The Ministry and its partners are hoping the Atlantic salmon will successfully spawn in the Credit River, Duffins Creek and Cobourg Brook, waterways where dozens of habitat rehabilitation projects are underway. The success of these pilot projects could result in other creeks being rehabilitated, and hopefully the widespread spawning of Atlantic salmon and their return in huge numbers to Lake Ontario.
• Atlantic salmon are native to Lake Ontario; however, by 1896 the species disappeared, due to dam building for hydro power, saw and grain mills, and farming and development on salmon spawning streams. Massive over-fishing in both spawning streams and Lake Ontario also hastened the disappearance of this heritage fish.
Project Partners and Sponsors:
- Australia’s Banrock Station Wines
- Credit Valley Conservation
- Ganaraska Region Conservation Authority
- Liquor Control Board of Ontario
- Ontario Federation of Anglers and Hunters
- Ontario Ministry of Natural Resources
- Toronto and Region Conservation Authority
For more information, contact:
- Marion Daniels, Management Biologist, Lake Ontario Management Unit, Ministry of Natural Resources, Peterborough (705) 755-1345
- Alastair Mathers, Lake Ontario COA Basin Coordinator, Lake Ontario Management Unit, Ministry of Natural Resources, Picton (613) 476-8733