eDNA and the Pembina’s Arctic Grayling
The distribution and abundance of Arctic Grayling in Alberta has steadily declined over the years. Habitat fragmentation, overharvesting by anglers, adverse land-use and the on-going influences of climate change have all played a part. To help with conservation efforts, Alberta’s Northern Lights Fly Fishers Chapter (NLFF) of Trout Unlimited Canada has been gathering data since 2011 on Arctic Grayling populations and habitat in the Upper Pembina River watershed. This work has been supported by grant funding from the Alberta Conservation Association. Each summer volunteer members, with guidance from provincial biologists, have checked creeks in the area to document evidence of size and location of Arctic Grayling populations. They’ve angled (under special license) many kilometres of stream to determine presence, size and number; taken fin clips for genetic analysis; recorded water temperature and flows; identified damage to stream banks, etc. Then, in 2022, the Chapter added a new and exciting aspect to its work by collaborating with the University of Alberta and Alberta Environment and Protected Areas on a study using recent advances in the use of eDNA (environmental DNA). The goal was to help validate which tributaries of the Pembina still contained populations of Arctic Grayling and thus help focus conservation efforts.
NLFF members were somewhat familiar with DNA, the hereditary material in us and all other organisms, but had some learning to do about eDNA, the cellular material shed into the water from skin, excrement and decomposition, and how to properly collect samples for testing by scientists back at the lab.
Thirty-six sites throughout the Upper Pembina were prioritized and selected for eDNA sampling. These were sites that showed the best available fish habitat – eddies, pools, and seams. The university team prepared the collection equipment and trained the rest of us for the field work. At each site, water samples were collected in 1-liter bottles attached to a long pole to avoid us stirring up any sediment which could influence results. Each water sample was drawn through a 1.2-micron filter which was then rolled up and placed into a tube containing a preservative known as ‘Longmire buffer’. All equipment was then sterilized before moving on to the next site.
The next part of the process, back at the lab, involved activities for which none of us NLFF members were qualified. Lab technicians isolated and purified the DNA from the filtered water samples, then amplified it using a process called “quantitative polymerase chain reaction” or qPCR. If a signal was detected using qPCR, then there was a high probability that Arctic grayling DNA was in that sample. A single cell from an Arctic Grayling could be enough to result in a positive signal.
Arctic Grayling populations were detected at 24 of the 36 sites sampled but, unfortunately, not at the other twelve. The majority of the non-detection sites were located in the Pembina mainstem and several tributaries in the far western portion of the project area. The 24 positive sites were mostly located in the middle part of the study area, including all sites previously tested by NLFF anglers on Rat Creek, Dismal Creek, and Nelson Creek and some sites on the Pembina mainstem. The data closely corresponded to the fish distribution that our volunteers had determined based on its 2011-2022 angling surveys.
The eDNA data also confirmed presence of Arctic Grayling at several sites where they had not been recorded during previous angling surveys. However, some of the reaches that were thought to be promising did not produce positive signals.
NLFF members not only learned a lot about current science that will be helpful in work to reestablish populations of fish at risk and of concern. We and others will now be able to focus our future activities on streams/reaches that have known Arctic Grayling presence. The results of the eDNA project will also certainly influence future management actions, including definition of areas most likely to respond to population recovery efforts. Perhaps too, this past year’s work will help identify the most promising location to achieve an NLFF dream – remote site incubation of Arctic Grayling to further help species recovery in the Pembina River system.