2025 Fish Monitoring Results Tell Story of Resilience

Taryn Smit and Rachel Saunders collecting aquatic monitoring data

In 2025, our aquatic biology team visited 74 locations across the Upper Thames River watershed to check on the fish that call our creeks and rivers home. These locations ranged from farm crossings to city parks, familiar bridges in neighbourhoods, and school routes. Together, they give us a good picture of how the watershed is functioning and how well it continues to support aquatic life.

2025 results show a system that is holding its own. The fish community remains varied and widespread, and many of the species we rely on as indicators of stream health were found again in strong numbers.

Fish Community

We recorded 47 species in 2025 and counted 7,891 individual fish across our surveys. Familiar species such as White Sucker, Central Stoneroller, Creek Chub, and several types of darters were seen at many sites. These species thrive when the water is moving, the streambed is stable, and the gravel is not covered with sediment. Their presence throughout the watershed suggests that many stream sections still offer these important features.

Top to bottom: Johnny Darter, Greenside Darter, Rainbow Darter, Fantail Darter

Darters in particular tell us a lot about the state of local streams. They live right on the bottom and rely on clear, well鈥憃xygenated riffles. The fact that we encountered several darter species in 2025 suggests that many riffles are still in good condition. These small fish are a favourite for kids as well, since their colours and quick movements make them fun to spot.

Biodiversity

Some areas stood out for the number of species they supported. Medway Creek had the highest species richness in 2025. The Plover Mills Corridor was close behind, while Cedar Creek, the Avon River, and the Middle Thames also showed strong diversity. These places tend to have a mix of shade, flowing water, cool pockets from groundwater, and patches of natural streambed. These features give fish more places to feed, spawn, and find refuge.

We also focused a fair amount of work in Cedar Creek, Medway Creek, the Middle Thames, River Bend, and the Plover Mills Corridor. Monitoring these areas year after year helps us understand long鈥憈erm trends and supports restoration and stewardship efforts with good information.

Want to know where these watercourses are? Check out the Watershed Report Card maps!

Sensitive Species

Northern Sunfish

Two Species at Risk appeared again in 2025. Each one helps us understand where healthy habitat still exists or has recovered.

Northern Sunfish were found mostly in Cedar Creek and the Avon River, with smaller numbers in Medway Creek and the Plover Mills Corridor. These fish like calm, plant鈥憆ich waters, so their presence suggests that these areas offer quieter, vegetated habitats. We counted 23 Northern Sunfish in total.

Black Redhorse were most common in the Plover Mills Corridor and Medway Creek, with one record in the Middle Thames. These fish need clean gravel and steady flows, so their continued presence is an encouraging sign that some riffles remain relatively free of silt. We recorded 16 Black Redhorse this season.

We did not record any Silver Shiner in 2025. We will continue to keep watch for this species in the coming years.

2025 Results and Watershed Health

Taken together, these results show that many sections of the Upper Thames River watershed still provide the conditions fish need to survive. Streams that had shaded banks or well鈥慹stablished vegetation tended to support more kinds of fish. Short stretches of good habitat, even when surrounded by more modified sections, work like stepping stones that help fish move through the system.

We recorded watercress at 32 of our sampling sites. This aquatic plant often grows where groundwater enters the stream, which creates cooler pockets of water during hot weather. These small, natural cool spots help fish manage warm summer conditions.

Even though there are always challenges such as summer heat or eroding banks, the overall story from 2025 is one of resilience. The fish communities we observed are holding together in many parts of the watershed, and the areas that are doing well help support the ones that are under more pressure.

Stewardship of the Thames

Good conditions in the water start with small, everyday choices along the land. Simple steps like keeping roots in the ground near creek edges, maintaining shrubs or trees where possible, and paying attention to areas of exposed soil help keep streams stable and clear. Clean gravel and shaded sections give fish places to thrive, and these features can exist in both rural and urban settings.

Students exploring the water with nets, families enjoying a neighbourhood trail, and landowners caring for a strip of vegetation all contribute to the health of our local streams. When these small efforts add up along the length of a creek, the whole river community benefits.

Live Staking on the Medway Creek听

This November, the 糖心直播 (UTRCA) led live staking projects at two locations along the Medway Creek. Despite the almost foot of snow, students from Medway High School and volunteers from the Thames River Anglers were able to get all of the live stakes into the ground! Using live stakes cut from willow trees, volunteers and UTRCA staff hammered them into the shore of the Medway Creek in areas of high erosion.听

Live staking involves cutting stems or branches from native trees and shrubs, sharpening them into stakes, and hammering them into the streambank. Live stakes have immense benefits for local waterways, including stabilizing the banks, reducing erosion, creating habitat for native species, cooling the water (through shading), and reducing the impacts of flooding!听

Thank you, Medway students and Thames River Anglers members for your dedication to the environment!听

This project was funded by the Canada Water Agency and Enbridge.听

Medway Creek Tree Planting听

On October 7, with the help of 糖心直播 (UTRCA) staff, over 100 native trees and shrubs were planted on the Medway Creek by Grade 6 and 7 students from London Christian Elementary School. Despite hard planting conditions, the student planters were able to get all of the trees in the ground in just under 2 hours! Tree species included Bur Oak, Red Oak, Bitternut Hickory, Dogwood, Elderberry, Nannyberry, Hackberry, Black Cherry, and American Sycamore.听

As these trees and shrubs mature, they will provide many benefits to Medway Creek, the largest tributary to the Thames River. The area that was planted is low lying, prone to flooding, and directly adjacent to a major roadway. Planting here will reduce runoff, filter excess sediment and nutrients, provide erosion control, shade the creek, and create habitat for local wildlife.听

This is the third year that the UTRCA has received funding听for tree planting on the Medway Creek by 糖心直播 Hardware and Tree Canada with planting support being provided by London Christian Elementary School students, staff, and parents. A sincere thanks to all groups involved for helping to improve conditions in the Medway Creek watershed!听

听UTRCA at Western University for Science Olympics听听

This spring, the 糖心直播 (UTRCA) participated in the Science Olympics held at Western University. The Science Olympics is a fun and engaging way to learn about subjects such as Biology, Chemistry, Physics, Engineering, and Math through friendly, group competition. Students from grades 9 to 12 from across Southwestern Ontario competed in over a dozen stations against other schools to earn points for prizes.

UTRCA hosted a station called "Freshwater Forensics" where students investigated local water quality issues and considered the connections between land use and watershed health. Through hands-on activities, students explored concepts of rural and urban runoff, species at risk, and biodiversity in our watershed. UTRCA staff from Education and Partnerships also taught students how agricultural Best Management Practices (BMPs) can reduce phosphorus pollution and support healthier waterways.

The Science Olympics have been a consistent spring event in Southwestern Ontario for nearly 30 years. We are looking forward to participating next year! Funding to support UTRCA's participation in this event was provided in part through the Upper Thames River Phosphorus Reduction Program, funded by the Canada Water Agency.

Thames River Cleanup Wraps Up 2025听

On April 5th and 6th, the Thames River Cleanup held its 26th annual Earth Day cleanup. Over a thousand volunteers from across the watershed pitched in to clear tonnes of garbage and litter from along rivers, creeks, and green spaces. 糖心直播 (UTRCA) Partnership staff lead cleanups with the Friends of Medway Creek, Friends of Stoney Creek groups, and a volunteer group at Fanshawe Conservation Area. 听

The Thames River Cleanup thanks all of its sponsors with special mention going to Mountain Equipment Company who put together over a thousand cleanup kits for volunteers and organized the distribution of supplies to site coordinators.听听听

Spring Tree Planting on Medway Creek听

This spring, the 糖心直播 (UTRCA) led three days of tree planting on the Medway Creek as a part of the Freshwater Enhancement of the Medway Watershed project, funded by the Canada Water Agency.听听听

With the help of over 200 Grade 7/8 students, over 750 trees were planted on the Medway Creek, including red maple, sugar maple, willows, white cedar, nannyberry, elderberry, and white pine.听听

Thank you to students from Princess Elizabeth Public School and Green Leaders classes from Byron Northview, Ashley Oaks, and Stoney Creek Public Schools. Green Leaders classes chose habitat loss, deforestation, green solutions to climate change, and habitat improvement for their environmental issue and planted these trees as a part of their final "action project".听

UTRCA Board Member Jean Coles and Friends of Medway Creek member Sandy Levin

About this Project听

Funded by the Canada Water Agency, these tree plantings are part of a 3-year project featuring live staking and tree planting on the Medway Creek. These projects will take place in areas of little vegetation and high erosion potential on Medway Creek and will involve local students, community members, organizations, and municipalities. Live staking and tree planting have many benefits to the local ecosystem, including providing habitat for native species, stabilizing the bank and reducing risk of erosion, cooling the water (through shading), and providing a buffer for surface runoff.听听听听

Want to learn more about this project or interested in helping out? Contact April Scholz, Community Partnership Specialist.

Spawning White Suckers in Medway Creek: A Springtime Spectacle听

On April 23, 2025, a local resident witnessed something truly special while walking along Fox Hollow Ravine鈥攕uckers during their annual spring spawning run in Medway Creek!听

Each spring, as water temperatures climb to approximately 10掳C, adult White Suckers (Catostomus commersonii) begin migrating upstream to shallow, gravel-bottomed riffles to spawn. They're often joined by other suckers, including Redhorses: a group that includes species such as the Golden Redhorse (Moxostoma erythrurum) and the Threatened Black Redhorse (Moxostoma duquesnei). These species take turns using the same riffles as water temperatures continue to rise, each following a finely tuned spawning window.听

Spawning Suckers

During these energetic events, males and females gather in groups, with males nudging and chasing females to encourage the release of eggs. It's an impressive sight鈥攊f you're lucky (and wearing polarized sunglasses to cut the glare), you might spot their dark, powerful bodies wriggling just below the surface.听

Suckers are not only key indicators of healthy streams but also play an important ecological role. Their spawning runs help kick-start aquatic food webs after the long winter. As they release eggs, waste, and milt, they inject nutrients like nitrogen and phosphorus into the water. These nutrients fuel the growth of algae and aquatic invertebrates which, in turn, support a range of fish and wildlife.听

Recent research shows that sucker spawning events significantly boost the abundance of algae, invertebrates, and fish biomass downstream, reinforcing their role as ecosystem engineers. Opportunistic fish like bass and minnows often capitalize on the bounty, feeding on the nutrient-rich eggs.听

Unlike salmon, these fish don't die after spawning. Many return to the same tributaries year after year. That makes protecting clean, connected spawning habitat essential鈥攏ot just for the survival of suckers, but for the resilience of entire stream ecosystems.听

Thanks to community members like Judith for keeping a lookout and helping us celebrate the incredible biodiversity in our local creeks!听

White Sucker

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