A common misperception of Trout Unlimited Canada (TUC) seems to be that its
work and interest are focused just on Canada’s rivers and streams and the fish
and aquatic insects that inhabit them. That’s not surprising when, for example,
Merriam-Webster dictionary defines ‘coldwater’ as ‘’running water”. Yet Canada’s
lakes and ponds and their aquatic life-forms are also an integral part of TUC’s
mission “to conserve, protect and restore Canada’s freshwater ecosystems and
their coldwater resources . . “
The health of these waters, including those that are stocked with cold water fish
species, primarily trout, are becoming of increased concern to organizations like
TUC, Alberta Conservation Association (ACA) and others, including the approx. 2.6
million Canadians who go fishing each year. Many of these lakes tend to be
shallow, enriched with nutrients and have seen an increase in water temperatures
in the last few years. Many of the ‘aquatic resources’, especially trout, don’t like
it! The level of dissolved oxygen (DO) that they need to survive is inversely related
to the water temperature, so as DO levels decline, the fish become stressed and
in some cases are unable to survive beyond mid summer. It’s especially so if the
water is stagnant and has a lot of rotting, organic material in it. Lake aeration
helps, but even with that, some lakes experience a decline in DO by mid summer
that trout cannot survive. And the problem seems to be becoming more
prevalent.
The Northern Lights Fly Fishers (NLFF) Chapter of TUC, based in Edmonton,
Alberta, became very interested when it heard of ACA’s efforts to address the low
-oxygen issue. After a thorough review of the research, ACA fisheries biologists
decided to try treating one of the ponds on its trout stocking list with a carefully
determined amount of alum to see if that might improve the water quality and
help maintain a sufficient level of DO to enable year-round trout survival. When
alum is added to water it reacts with the phosphorous and other pollutants
causing them to clump together and settle to the bottom of the pond. This
process, known as flocculation, helps to remove suspended particles from the
water and reduces nutrients available for plant growth. Less growth results in less
organic decay and thus less of that much needed DO being used up by the decay
process.
NLFF offered volunteer help and successfully applied for an ACA Conservation,
Community, and Education grant to help with the costs involved. Rainbow Park
Pond in Westlock, Alberta, a popular stocked fishing pond but with a history of
winterkill and low fish survival in the summer, was selected as the test site. NLFF
then provided local information on the project via the media. It also collected
temperature and alkalinity data on a number of other stocked ponds in the
greater Edmonton region which further evidenced similar adverse conditions for
trout.
So far, it’s looking promising for improved water quality at Rainbow Park – alum
treatment has reduced total and dissolved phosphorus concentrations. But the
benefits of the alum treatment won’t be fully known for a few years. There’s a lot
of decaying material from previous years to work through, but hopefully DO
concentrations through this winter will be higher than in previous years and algae
growth will be less next summer, both of which are necessary to restore this pond
as a viable, year-round, trout fishery.
Although it’s not the health of flowing waters that the project is trying to restore,
it is certainly an attempt to find a way to restore a freshwater ecosystem and its
coldwater resources. That it’s a partnership between different organizations with
similar goals is an added bonus for the conservation of trout-friendly waters and
for Alberta’s anglers.
