E-DNA Study on Creeks in the Nechako Watershed
Sep 1, 2024
Document: Background
Environmental DNA (eDNA) is a way scientists study living things in an environment without having to see or catch them directly. When plants, animals, or other organisms live in an area, they shed tiny bits of DNA into their surroundings through things like skin cells, hair, or waste. This DNA can be found in water, soil, or air.
Scientists collect samples from these environments and analyze the DNA to figure out what kinds of organisms are present, even if they never actually see the organisms themselves. It's a powerful tool for studying ecosystems, tracking endangered species, or detecting invasive species, all without disturbing the environment much.
Nechako Watershed Study
As part of a project to study environmental DNA (eDNA) in the Nechako watershed, water samples were collected from 39 creeks and rivers. These locations spanned from areas west of Prince George, such as the Chilako River, to the Nechako Canyon near Cheslatta Falls, and further west to creeks like Ormand Creek and the Endako River, which flows into Fraser Lake. Sampling was conducted at 64 sites over three months—June, July, and August—to detect four salmon species: chinook, sockeye, coho, and rainbow trout.
The findings indicated that rainbow trout and juvenile chinook salmon were present in many of the creeks throughout the study period. Sockeye salmon were detected in some areas, though their presence is more complex due to interactions with kokanee salmon. Coho salmon, which hadn't been detected in previous surveys, were found in several creeks in August. This may be due to the inclusion of additional sampling sites and the migration of coho to their spawning locations.
Overall, the study provided clear evidence that these salmon species use the Nechako watershed extensively. This data will serve as a baseline for future restoration projects in the area, particularly around creeks like Murray, Knight, and Clear.
Results and Discussion
No evidence of contamination was found in the control samples, confirming the reliability of the results. At least one salmon species was detected at 117 out of 121 sites. Sites where no salmon were found included some in Murray Creek, where restoration projects are planned, and Engen Creek, which has limited connection to the Nechako River.
Rainbow Trout: Rainbow trout were found in most creeks, with strong signals detected in many locations. This species is common throughout the study area, indicating the effectiveness of the sampling methods.
Chinook Salmon: Chinook salmon were detected in most creeks that flow into the Nechako River or Fraser Lake. Their presence throughout the summer, especially near confluences, highlights the importance of these habitats for juvenile chinook.
Sockeye Salmon: Sockeye salmon were detected in some creeks, particularly in the June samples. Their presence in certain areas suggests that juvenile sockeye may be present throughout the summer. However, in areas like Cluculz Creek, strong signals in August likely reflect kokanee spawning.
Coho Salmon: Coho salmon were detected in multiple creeks in August, especially in new sampling sites between Prince George and Fraser Lake. This is significant because coho had not been detected in previous surveys, suggesting they may be migrating to these areas for spawning.
Restoration Sites: Several sites were chosen for their connection to ongoing or planned restoration projects. For example, sites on Clear and Eden creeks showed the presence of rainbow trout and coho, while Knight Creek had chinook salmon in June. These results will serve as baseline data for evaluating the success of restoration efforts.
November Sampling: Additional sampling in November focused on the upper Nechako River to determine if late-migrating species like coho were present. While chinook and rainbow trout were detected, no coho were found, contrary to stakeholder expectations.
Beaver Dam Complex: Since 2021, studies have been conducted on how salmon use a growing beaver dam complex on Murray Creek.
Read the complete study summary here:
