When picturing the species of a river or stream, most people think of fish first. Unless of course they’re Kris Kendell, who has always been fascinated with the less obvious amphibians inhabiting the water’s shorelines. 

“As a kid I would be out in nature and I would hear some noise coming from a wetland and I would naturally want to explore it,” he says. 

Amphibians, which includes frogs, toads and salamanders, are typically harder to see than fish, especially while they hibernate in the winter months. For Kendall, their near invisibility is what makes them so unique.

“Over the winter as a kid, when I did encounter them, it would always be something special because it wasn't like they were always around and they took some searching for,” he recalls. 

When they finally did emerge in the spring, Kendall says their choruses during the mating season were always a sign warmer weather was coming. 

While Alberta native trout and amphibians usually have very little in common, like trout, amphibians are important indicator species for their environment and are also facing increased threats from habitat loss, pollution and disease. 

On top of all that, efforts to stock ponds and wetlands for fishing with both native and non-native trout species can also harm amphibian populations, prompting biologists and advocates to call for deeper consideration of the complex interactions between amphibians and trout in conservation work to preserve both species.

Monitoring a challenge amid population threats

Alberta has 10 amphibian species — two salamander species and eight types of frogs and toads. Of these, only three are considered secure, while the rest are either ranked as ‘sensitive,’ ‘may be at risk’ or ‘at risk’ under the province’s general status rankings. 

According to Wildlife Conservation Society Canada, 56 per cent of Alberta’s frogs are endangered, representing the second-highest behind British Columbia.

The seven species who are of conservation concern are largely found in the southern portion of the province, says Cynthia Paszkowski, a professor emerita at the University of Alberta. 

She says this is because there are more species in the south and they tend to be habitat specialists, meaning they can only survive in very specific conditions.

But unlike other, more visible species, exact population numbers of amphibians are unknown. Paszkowski says this is due in part to the sheer number of wetlands and waterbodies across the province, with many being difficult for researchers to get to.

“Many of them in the northern part of the province are very inaccessible and likewise in the mountains,” she says, adding prairie wetlands can be remote too. 

“It's difficult to keep your pulse on that when you have so many different localities,” she says.

Additionally, monitoring species based on breeding activity can be problematic as many species do not breed regularly, especially if the conditions are unfavourable. 

Paskowski says this can give the impression there are no amphibian species, when in reality they’re just inactive.

Kendall, who is a wildlife biologist with the Alberta Conservation Association (ACA), agrees, adding species will fluctuate depending on if the weather is hot and dry, or rainy and wet. 

“It's a bit subjective because during dry-hot conditions, amphibians may switch their activity to being more at night, or they may be more undercover to escape unfavorable conditions,” he says. “There could be lots of them, but we just don't notice them.” 

Unwanted mixing and mingling

The relationship between native trout and amphibians can be intricate at best.

On the one hand, all of the amphibian species in Alberta spend most of their time in moist, terrestrial areas after hatching and maturing in water. Any water they do inhabit, is shallow, and warm — the exact opposite of the deep, cool water trout prefer.

Paszkowski, however, says there are instances where trout and amphibians may come into contact, such as in headwaters both species have historically lived in, or, in more insidious instances, where ponds have been stocked with trout for fishing.

Trout do not typically eat amphibians or their tadpoles and larvae, instead preferring large invertebrates and smaller fish. In rare cases, they may prey on frog species like the northern leopard frog, who hibernate at the bottom of streams.

“They're completely inert, lying at the bottom of a slow-flowing stream, and they breathe through their skin,” Paszkowski says. “Now this would be a situation where potentially a trout, say maybe rainbow trout, could come in contact with an amphibian in winter when the amphibian is basically knocked out … and could eat them.”  

Stocking trout in an area they would already be isn’t a problem, Paszkowski says. The main issues occur when it’s assumed native trout are native to every waterbody in the province. 

“If it's not a very productive system, the trout are going to pretty much have to eat whatever they find there,” she says, adding this means tadpoles and larvae. 

But in a more productive environment, meaning the trout have enough food sources, Paszkowski says they can actually help by eating large invertebrates who prey on amphibians’ offspring. 

‘Canaries in the coal mine’

While native trout and amphibians have different environmental needs, both provide important signs of an ecosystem’s health.

Referring to them as the “canaries in the coal mine,” Kendall says amphibians are important indicator species for their environment, and can tell scientists a lot about both land and water.

“They can tell us the health of their aquatic systems because part of their life cycle is in aquatic systems, and then also part of their life cycle is on land, so they can also tell us how their land is doing,” he says.  

Amphibians also breathe through their thin, permeable skin, meaning they can also easily absorb chemicals and other contaminants, telling biologists about the quality of the environment. 

Similar to native trout, Kendall says amphibians also need healthy riparian zones to act as buffers for chemical run-off and provide hibernation locations. Conserving these areas for native trout can also benefit amphibian populations.

“Those buffers along these water bodies can serve the fish very well, and that's also where amphibians are breeding,” he says. “They all benefit from that riparian habitat.”