Looking for Clues: The Case of the Missing Bull Trout

Looking for Clues: The Case of the Missing Bull Trout

Looking for clues

Imagine a species has become curiously absent or rare in your local watershed. Where do you start to look for answers, and what exactly should you be looking for? Is the species really gone? What happened?

These are some of the mysteries involved in species recovery. Sure, it is easy to point the finger at a single issue; habitat loss, invasive species, climate change, overexploitation, pollution, poaching, disease, take your pick. In reality, the suite of threats facing native species (in this case fish) is usually complex, numerous, and ever-changing. Making things even more difficult is the fact that fish, especially Bull Trout, can be hard to find, track, and count. In order to develop an action plan to recover at-risk populations, we need to first gather information on what is impacting them. In the case of the Tay River watershed, the mystery TUC and partners are trying to solve is, where did the Bull Trout go?

Why the Tay River?

Alberta’s Bull Trout populations were recently added to the federal Species at Risk Act. Populations in northern Alberta (Peace and Athabasca basins) are listed as Special Concern and populations in the North Saskatchewan, Red Deer, Bow, and Oldman basins are listed as Threatened. With such a large range, why focus efforts on the Tay River watershed? In a perfect world, we may have the resources and capacity to recovery at-risk fish species everywhere, but in reality, there are some places where it will be too difficult or perhaps the trade-off or costs too great to see meaningful recovery. Fishery managers and partners have prioritized several larger watersheds for recovery actions, one of which is the Clearwater River in west-central Alberta. Downstream of the Tay the recovery potential is pretty low and upstream of the Tay the Bull Trout are hanging on. The Tay represents the “front line” of recovery efforts. The habitat is relatively intact and water temperatures are suitable for Bull Trout. Historical information suggests there once was a robust population of Bull Trout but few remain. There is no “smoking gun” that has caused the Bull Trout declines but rather the cumulative effects of multiple threats. The challenge is to figure out what is actually causing issues on the ground and how we can address them.

Looking for Clues

With funding through the Alberta Conservation Association’s Conservation, Community and Education Grants program, with support from Alberta Environment and Parks (AEP)  and several project partners including AEP Fisheries Management, Alberta Agriculture and Forestry (AF), Foothills Research Institute (FRI), Cows and Fish, and the TUC Central Alberta Chapter, and West Fraser (WF), our Bringing Back Bull Trout – Tay River was launched in 2019, focussing mainly on assessment but a few restoration activities took place as well including planting over 600 willow stakes along 300 meters of streambank and constructing a live wattle fence to stabilize a large slumping bank.

Fisheries Assessments

AEP and TUC carried out fisheries assessments using backpack electrofishing at 30 sites in August 2019 to document the current fish community in the mainstem and tributaries of the Tay River. Volunteers from the Central Alberta Chapter also participated in one of the electrofishing days. While a variety of fish species were captured throughout the watershed, no Bull Trout were captured at any of them. However, a few chapter members did catch a couple of individuals by angling later in the year. The most abundant species captured by far was Brook Trout, making up 77% of all fish captured with 153 individuals turning up during electrofishing.

Temperature Monitoring

Looking for Clue
Photo Credit: Sam Hoffe

Water temperature data loggers were deployed throughout the watershed at 11 locations in spring 2019 and ten were recovered (one leftover winter) and downloaded in the fall. Overall, water temperatures were within the healthy range for Bull Trout with the exception of a handful of days at sites in the lower watershed during August where temperatures exceeded the optimal range of 10 – 14.5°C. Overall, temperatures in the mainstem Tay River were higher than in tributaries, as expected.

Identifying Sediment Sources

TUC and AEP have been working with AF and FRI to validate the Road Erosion and Delivery Index (READI) model in the Tay River watershed. Data is still being analyzed for the Tay, but the model identified several priority areas where linear features (roads, trails, etc.) are delivering sediments to a watercourse. In addition to the READI model, TUC also hired Aquality Environmental Consulting to conduct an inventory and assessment of trails and stream crossings in the watershed in 2019. The findings of their assessment identified a number of stream crossing areas being used by motorized vehicles which should be reclaimed or bridged to improve stream health; we are working on engaging user groups in the region to better understand seasonal use and develop relationships to support rehabilitation at these sites.

Riparian Health Assessments

Cows and Fish completed Riparian Health Inventories (RHI) at nine sites throughout the watershed. Overall, the watershed scored healthy with an average score of 88% across the nine assessed sites, with eight sites considered healthy and one site falling in the healthy with problems category. While these sample sites are small and don’t necessarily represent the totality of riparian health in the watershed, these findings suggest that at a glance, riparian health issues may not be a significant concern for fish habitat. The RHI sites were all located on public lands and one assessment was done on private land. Clearwater County, through its Clear Water Land Care program, helped us reach out to private landowners and two individuals have stepped forward expressing interest in learning more about riparian health management.

Quantifying Habitat Fragmentation

AEP completed an inventory and assessment of potential obstacles to fish passage in 2017 and 2018 and identified a number of potential crossings where fish passage may be impeded. Sundre Forest Products is active in the area and completed a major culvert replacement project during 2019 to improve passage at one of these sites by replacing three undersized culverts with a full-span bridge. This work will restore the free movement of fish to the upper reaches of a major Tay River tributary. TUC will continue working with our partners to address fish passage at crossings throughout the watershed, as well as celebrating the work that is being done already.

Next Steps

TUC will be busy in 2020 working towards bettering our understanding of the threats facing Bull Trout in the Tay River watershed with our project partners. We are also using the information we gathered during this year to refine a rehabilitation plan to guide our work. There will be lots of opportunities to get involved with habitat rehabilitation, redd surveys, electrofishing inventories, and a number of additional workdays planned throughout the spring, summer, and fall! Please contact Project Biologist Elliot Lindsay, if you are interested in learning more!