Fish who call the Credit River home

Fish who call the Credit River home

The salmon migration may be one of the biggest attractions in the Credit River during fall, but what about all the other fish? Brook trout and brown trout spawn in fall too, but in smaller and quieter sections of the Credit River and its tributaries. Compared to migratory species, these resident fish spawn close to home.

Brown trout. Photo credit: Jon Clayton

Here are our top eight facts to highlight brook and brown trout:

1. Brook trout aren’t really trout at all. They’re actually char and more closely related to Arctic char than to rainbow trout.

2. The World Record brook trout was nearly three feet, weighed 14 pounds and nine years old.

3. Brook trout will only spawn on groundwater upwellings, where deep, cold water rises toward the surface. Other trout and salmon are less selective when they dig their nests, called redds, in gravel.

4. The colouration of male brook and brown trout intensifies during the spawning season to help them attract a mate.

Brook trout. Photo credit: Jon Clayton

5. Both brook and brown trout can spawn multiple times over the course of their lives, unlike Pacific salmon who only spawn once. A large female brook trout can produce about 5,000 eggs each spawning season.

6. Despite being considered resident fish, brown trout do some travelling. They often swim tens of kilometers, often only to return to their starting location.

7. Brook and brown trout are sensitive species because they require cold and clean water to survive and thrive. They’re also considered “indicator species” because their presence serves as a measure of the health of the Credit River. Brown trout are non-native but have been naturalized.

8. Trout and salmon are just one of over 20 families of fish in the watershed.

Brook trout. Photo credit: Jon Clayton

More than 70 fish species call the Credit River Watershed home. Our Integrated Watershed Monitoring Program (IWMP) monitors resident fish communities. We usually collect, study and release forty or more species and thousands of individual fish each year.

Learn more about brook and brown trout and other species found in the watershed.

Learn more about our Integrated Watershed Monitoring Program.

Have any cool photos of brook and brown trout? Share your photos with us on Instagram, Facebook and Twitter.

By Kurtis Plourde-Rideout, Technician, Watershed Monitoring

10 Comment
  • Stephen Stepanic says:

    Really appreciate the effort in these emailers ! Thanks so much , keep up the great work, I’m learning much.
    all the best.


  • Ann Seymour says:

    Re. The Erin Waste Water Treatment Plant Effluent
    The West Credit River and accompanying Brook Trout Fishery will not manage the effluent temperature, effluent content and urban drainage from Wellington County directly into an up-welling of a cold water spring at Winston Churchill. The population growth number for the Town of Erin needs to be reduced to a rational and reasonable number that this sub-watershed can manage. In addition alternative sewage treatment technology is required. Stop allowing Mayor Alls from using the CVC’s good reputation in statements that endorse this excessive development. The CVC has concerns. The EWWTP is designed for failure. You are allowing the permanent degradation of West Credit River biodiversity. Plus, why are the receivers, in Belfountain, of Erin’s waste water not considered stakeholders?

  • Anna says:

    Thank you, I learned a lot about the fish that call the Humber River their home…so very interesting.
    Thank you so so much for all the wonderful work you do!

  • Jenni LeForestier says:

    The EA was “approved” but was not satisfactory in any way as the study of the brook trout was done at the wrong time of year. Are the recommendations made by the CVC being adhered to by the 10 developers funding the Water Treatment Plant? What plans does the CVC have for brook trout that are spawning in the tributaries?
    The chloride in the effluent from the Orangeville Waste Water Treatment Plant killed the brook trout in the Credit River. The same will happen to the West Credit

    Oil is being dumped at the south end of the Credit River is it then ok for the town of Erin to dump effluent at the north end?

    What is the CVC actually doing to protect the brook trout?

  • Karen says:

    I have a few questions. How will fish in the West Credit survive partially-treated sewage – since no plant can deal with all the toxins and drugs people flush? The Credit south of the Orangeville WWTP is dead and the attempt to reintroduce fish there failed (i.e. they all died). So, even though there was an EA for the Erin WWTP, how was it funded? Did anyone involved have a vested interest? Why were no other locations for the WWTP considered? With an increasing Climate Crisis looming, and severe weather events that can include sudden storms, flooding and wild temperature swings, how can anyone guarantee that the fish habitat will be undamaged by a sewage plant? Was the person at the MoE who approved the EA a scientist or a career politician? When one speaks to an actual scientist who knows about rivers, it is glaringly apparent that this EA should never have been passed and that the WWTP is a disaster in the making for the native fish in the West Credit River. Biodiversity needs to come before sewage or our world will soon face some much bigger problems than the loss of a fish habitat.

  • Sara says:

    Brown trout do more than ‘some traveling’. They are partially migratory, with some individuals resident, and others migrating to the lake (the camera at Streetsville showed migratory brown trout moving upstream). Also, brown trout are not particularly ‘sensitive’, and do well in warmer water. Also, what do you mean by “Compared to migratory species, these resident fish spawn close to home”? What is ‘home’? Where they were hatched, or the lake? It’s an unclear statement.

    • Thanks for your comments, Sara. We appreciate your thoughts. We passed your questions along to an expert and here is what they had to say:

      Brown trout do more than ‘some traveling’. They are partially migratory, with some individuals resident, and others migrating to the lake (the camera at Streetsville showed migratory brown trout moving upstream).
      – Agreed, there are both resident and migratory Brown Trout populations in the Credit. A 2004 study looked at Brown Trout movement in the middle Credit and found range limits of up to 26.3 km, with the fish in the Terra Cotta – Inglewood section moving the most. The study also stated that downstream movement beyond the Norval is thought not to occur. I suspect that the Brown Trout going past the Streetsville camera are migratory and just access the Credit to spawn, rather than being year-round residents. These fish would be able to access the river up to the dam in Norval.

      Also, brown trout are not particularly ‘sensitive’, and do well in warmer water.
      – Agreed that Brown Trout are better suited to warmer water than Brook Trout, however Brown Trout still require colder water with good oxygen levels. Adult Brown Trout disappear from our fisheries surveys by about Glen Williams as water temperatures begin to increase beyond their thermal tolerances.

      Also, what do you mean by “Compared to migratory species, these resident fish spawn close to home”? What is ‘home’? Where they were hatched, or the lake? It’s an unclear statement.
      – The Brown Trout in the Cataract – Terra Cotta reaches of the Credit are considered resident and while they do move seasonally, their “home” would generally be considered the Middle Credit. Brown Trout in this section are also considered to be self-sustaining. Also, studies have shown resident Brown Trout have been known to move up or downstream ten’s of kilometers only to return to the exact spot where they started.

      Please let us know if you have any further questions and again, thanks for reading this article!

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