Being Kind to Our Fish This Summer

In British Columbia, this summer is expected to be dry, dry, dry. In all but the most northwest parts of the province winter snowpack accumulation is well below the annual average. At the time of writing, the Morrissey Ridge station closest to Fernie recorded a snow water equivalent 41% below the 30-year average. In the broader East Kootenays, the snow basin index is 24% below normal. This means that we’re in for a dry summer, with low water levels, and high water temperatures: this is bad news for mountain fish. 

Too Hot to Handle
Unlike humans, fish are cold-blooded and don’t regulate their internal body temperature. Instead, their metabolism depends on the surrounding water temperature; higher temperatures lead to increased metabolic rates. In general, mountain fish thrive in cool streams, so warmer temperatures can induce heat stress protein release. Westslope cutthroat trout, for example, can tolerate temperatures of 1-20°C, and have a preference for 9-14°C. Anything that exceeds their physiological limits causes heat stress, and at water temperatures above 24°C mortality rates start drastically increasing.

Tackling the larger issue of climate change driven drought and temperature rise is a goliath, but there are small actions we can all take to be kinder to our fish.

Don’t Dam our Streams
Hanging out by streams is a popular pastime to escape the heat of summer. Boat launches, lakes, and creeks are chock full of locals and tourists dipping in and cooling off. During low water levels some creeks aren’t deep enough for a satisfying dip and, as a solution, some people build little dams to create pools for lounging. While this seems harmless, it can have adverse effects on fish. Dams restrict waterways, preventing fish from accessing colder upstream areas. Additionally, slower water heats up quicker than fast moving riffles, resulting in warmer waters. For this reason, building rock pools is discouraged, but if you do build one, certainly make sure to take it apart when you leave.

Handle with Care
Fish already undergoing heat stress are more likely to suffer mortality from excessive fish handling. There are several things anglers can do to decrease fish stress. First, you can decrease the line time (how long a fish spends struggling on the line while you reel). Second, keep the fish in the water the whole time while unhooking and releasing: air exposure is one of the greatest fishing related stressors. If you want to take a photo, keep your camera ready and take a picture while the fish is under water in your rubber net. Finally, consider not fishing during hot days and in highly fished areas to protect our valuable resource. 

Slow Whirling Disease Spread
In Yoho and Kootenay National Parks, all water bodies are closed for recreation until March 2025 due to the detection of whirling disease in BC’s Emerald Lake last Fall. In Waterton Lakes National Park, waters are closed to any outside watercraft. Such a fate is on the precipice for the Elk River Watershed, as our waters are a mere 15-minute drive from the infected waters in the Crowsnest area. Whirling disease is caused by a small parasite and can result in high mortality of young fish. The parasite spore is hardy and can withstand long periods outside of water. This makes it especially capable of spreading via wet or dirty equipment that is transferred from one waterbody to the next. Once the disease has spread, eradication is virtually impossible, so efforts to slow the spread are the most prudent preventative measures. Make sure all your equipment is fully cleaned, drained, and dried, especially when moving between water bodies. To learn more about whirling disease visit