How will warming affect Stoney Lake's sportfish?

by Emily Swick

My name is Emily Swick; I'm a M.Sc. student at Trent University and the newest member of the Stoney Lake Tracking Project. I started at Trent in May 2025 and I’ve spent a lot of time on Stoney this summer and fall! Below you can see a photo of me aboard RV Ingleton helping with our annual receiver download this past summer.

We’ve tagged a wide range of fish species in Stoney Lake, including musky, walleye, smallmouth bass, largemouth bass, yellow perch, black crappie and lake whitefish. While some of our tags just tell us about the movement of the tagged fish around Stoney Lake, other (fancier) tags are equipped with more advanced sensors and collect detailed information on fish acceleration, depth, and even body temperature.

For my project, I get to use this data to answer a few big ecological questions about walleye and smallmouth bass. These fish are both popular sportfish loved by many anglers (including myself) and top predators, so they are important both economically and ecologically. They are thought to differ in their preferred water temperatures; walleye are cool water fish while experts will tell you smallmouth bass do better in warmer water. One of the big challenges in biology is to understand and predict how wild animal populations will respond to climate change. Rising water temperatures affect fish species in different ways. As water temperatures continue to rise, those changing conditions could create “winners” and “losers” in the fish community. We’d expect cool-water species like walleye to lose out, while warmer-water species like smallmouth bass may benefit. However, that’s just a prediction; one we need to test and evaluate using a variety of different types of evidence. Figuring out how fish populations are likely to change in the coming decades can be very useful for fisheries planning and for prioritizing conservation efforts.

For my project, I want to answer two big questions about Stoney Lake walleye and smallmouth bass:

1.    How does water temperature influence fish growth?

2. What water temperatures do fish prefer?

To answer the first question, I will use Bioenergetics modeling. Energy is a currency for all animals, like money is to us. Fish need energy for both the cost of living (like the cost of rent or bills for us) and to grow (this is like their savings).  When fish consume energy through food, this is like their paycheck. If water temperatures get high enough, fish growth decreases because the “cost of living” goes up for the animal (water temperature is like inflation). Having accurate estimates of metabolic costs is important when using bioenergetic models to estimate fish growth. For the fish in Stoney Lake, we can estimate how their metabolic costs vary across space and time for each animal we’ve tagged, using accelerometer tags (our fish “Fitbits”). With these more accurate estimates of fish “living expenses”, I will create models that seek to explain how growth is affected by temperature and by the behavioural strategies used by walleye and smallmouth bass, both in current conditions and under future warming scenarios.

For the second part of my masters project, I will look at the temperature preferences of Stoney Lake walleye and smallmouth bass. Fish are cold-blooded, so their body temperature is the same as the water temperature around them.

Fish can’t regulate their internal body temperature like we can, but they live in an environment with a range of different temperature options. By swimming into shallower or deeper parts of the lake, they can warm up or cool down as needed. Using tags that tell us the depth of the tagged fish, along with the water temperature at that depth, which we record year-round, I will calculate fish body temperature and determine what temperatures these fish are choosing. Knowing these temperatures will allow us to predict how at risk these fish will be as the temperature profiles of our lakes continue to change in the coming decades. 

I am at the early stages of my project and will spend this winter (as most fish scientists do) analysing the tracking data we have for walleye and smallmouth bass in Stoney Lake. Stay tuned for results!

Join us august 16 for new fish tracking insights

Join researchers from Trent University and Fisheries and Oceans Canada for an informal afternoon to hear the latest insights from the Stoney Lake Fish Tracking Project.

We'll be sharing:

•  What we’re learning about fish behaviour on Stoney Lake •  How data can help protect habitat and manage local fisheries •  Where the research might go next — and how your input can help shape it

Event Details: Viamede Resort – Kawartha Room 595 Mt. Julian Viamede Rd, Woodview, ON Saturday, August 16, 2025 🕑 2:00 p.m. – 3:30 p.m.

This complimentary event has no RSVP requirement. Parking is available in all three Viamede lots with access to boat docking.

We hope you’ll join us for an engaging conversation about the future of our lakes. Graham Raby, Associate Professor, Biology Trent University

P.S. Have a question or want to suggest research directions? There will be time after the presentation for Q&A and community input!

A preliminary look at what sportfish are up to in Stoney Lake

By Amber Fedus, PhD Candidate at Trent University

After a long year of waiting to download our receivers, we recently ran some preliminary analyses which we shared with the community in our annual update meeting at Viamede Resort in August (2024). Some of you may have been present at our update meeting (thank you for those who made it!), in which case you may have seen these results. But we are sharing it here for those of you who missed it.

Many of the tags we’ve deployed into fish the last couple years have acceleration, pressure (depth), and temperature sensors in addition to telling us the fish’s location. From these sensor tags, we get a lot of finescale data that can tell us more about the fish’s behaviour. Acceleration sensors give the activity levels of fish, with higher acceleration values meaning the fish are swimming more, which can be indicative of foraging. Combining the activity data with the depth and temperature the fish are choosing can help reveal how the foraging strategies of fish differ, within and among species.

Figure 1 (above). Average activity levels of walleye (left) and smallmouth bass (right) over a 24-hour period from July – August 2024. This shows that walleye are more active from sunset – sunrise and smallmouth bass are more active during the day, suggesting these two species have opposite behaviour patterns in feeding.

Overall, our data suggest that fish are more active in the summer than in winter, which makes sense because cold temperatures really slow fish down. Walleye specifically are adapted for nocturnal foraging; their eyes help them see prey in low ligth. Our data shows this as their activity is much higher at night than in the day, with peaks at sunrise and sunset (Figure 1). Smallmouth bass, on the other hand, are active primarily during the day (Figure 1). We don’t see much activity from them at all as soon as the sun sets. This becomes important when considering how these two predators are able to co-exist,  these as they have very similar diets and inhabit very similar areas of the lake according to their network plots (Figure 2). In fact, one question we had prior to analyzing the data was how the walleye and smallmouth bass can inhabit the same areas without one out-competing the another. The answer to this question may be that these two species have opposite feeding schedules, allowing them to occupy the same habitat but feed at different times.

Figure 2 (above). Network diagrams for walleye (left) and smallmouth bass (right) for July – August 2023. These plots show the connections and interactions between individuals and locations. The yellow circles show receivers that act as “hubs”, which are frequented more by the fish (larger circles = more fish detected there). The red lines show connections between the receivers in terms of movement, with darker/thicker lines indicating a stronger connection between those receivers.

Figure 3 (above). Activity levels of muskellunge over a 24-hour period from July – August 2024. This shows that musky are more active around sunrise and sunset.

Musky, on the other hand, show higher activity levels corresponding to the first couple hours of dawn and dusk (Figure 3). These peaks in activity suggest that these are times musky are actively hunting. The data we have only represent the 7 musky we tagged in 2022-2023. We tagged a ton of new muskies this year, so we will have way more data on their behaviour when we download the receivers next spring.

While the results presented above represent averages for each species, some interesting analyses lie ahead for us in looking at variation among individuals of the same species. An example of this is evident in Figure 4 (below). Individual walleye seem to have a wide range of depths (relative to the surface) they choose to occupy. This is something we will be diving into in future analyses to better understand among-individual differences in behaviour, including how persistent they are over time.

Figure 4. Differences in depth among individual walleye tagged with V13A and V13AP tags for July – August 2023.

We have some work being done on habitat modeling led by Jake Brownscombe (DFO). Currently, our data only show us the receiver the fish was detected, which means the fish could be anywhere in the radius of the receiver’s detection range. Habitat modeling will allow us to apply chemical, physical, and structural measurements we’re taking throughout the system to gain incredibly detailed insights into preferred habitats in the lake. We are also actively working on collecting samples for stable isotope analysis, which will allow us to determine each fish’s feeding habits and map out the food web in each lake.

Stay tuned for future updates. Get in touch if you have ideas for topics/questions we could address with the data.