If you have used an ancestry kit, or watched a favorite crime series, you know that the use of DNA (or deoxyribonucleic acid) is more mainstream today than it was 20 years ago. DNA is the set of biological instructions unique to every organism. Although DNA’s chemical structure is the same for all organisms, the unique sequences of base pairs create differences among individuals, species, and populations.
eDNA (or environmental deoxyribonucleic acid) is DNA shed by an organism (via skin, excrement, mucous, hair etc.) as it moves through the environment. eDNA can remain in the environment for up to three weeks and, for aquatic species, is collected in a water sample. For example, fish poop contains DNA, and can be transported a small distance by water currents. Once in the environment the DNA is slowly broken down by the sun and heat. If you collect a water sample one week after a fish pooped, you may capture its DNA. This DNA collected allows fisheries managers to understand which fish species are using different parts of the watercourse.
Recent technology advances have made eDNA a desirable way to sample fish populations. Quick, cost effective, and standardized (allowing comparisons from site to site), fisheries managers are using eDNA to replace traditional methods such as gillnetting, electrofishing or angling, which can be more time consuming, costly, labour intensive and require handling fish. eDNA sampling requires a single person (in our case a volunteer from our community) to collect a water sample. DNA is filtered from the water sample and sent to a genetics lab to detect target species DNA (in our case Brook Trout), using PCR (polymerase chain reaction).
Community knowledge tells us that Brook Trout have historically lived in the mainstem and tributaries of Squirrel Creek, just south and east of the village of Millbrook. Over time, water temperatures in Squirrel Creek have increased. Less habitat is now available for Brook Trout as this species prefers temperatures below 21°C.
Squirrel Creek does have an advantage over many native Brook Trout streams in southern Ontario. To date, there is no sign of non-native Brown Trout, known to outcompete Brook Trout for resources, reducing Brook Trout survival rate. Therefore, if temperatures are suitable, Squirrel Creek Brook Trout have a great chance to survive and thrive.
Trout Unlimited will be completing an eDNA study in August to provide a snapshot of the distribution of Brook Trout in Squirrel Creek today. This information will go directly to landowners so that they can understand where this species lives, and what makes the habitat suitable. Work has already been completed to understand the thermal status of each section of the creek (warm, cool or cold-water). Efforts will target the cool and cold-water reaches, which Brook Trout prefer. We have landowner permission to access the creek in many of these cool and cold-water reaches.
For more information about this project or about our organization, please contact Trout Unlimited Chapter Millbrook (troutunlimitedmillbrook@gmail.com) or check out our Facebook page.
By Trout Unlimited Millbrook
