Trout Talk

Put a thermometer in your pack ... and use it

A water temperature thermometer.

One of the greatest threats to the trout and salmon we love is a warming climate that comes armed with a one-two punch of declining winter snow and warming summer water temperatures.

Trout need cold, clean water. Simple as that. For most trout, water temperatures that approach 70 degrees prove troublesome and often fatal. Water temperatures that rise into the mid-60s can make trout listless and sluggish. It’s up to us to know when the waters we fish might be working against the trout we’re after. Put a water temperature thermometer in your vest or pack, and by all means use it liberally.

Summer is certainly the time when our favorite fish are stressed the most. Not only do the fish see more pressure from anglers, but warmer daytime temperatures can cause unhealthy spikes in water temperature. Even in higher-elevation rivers and streams, warm water can be an issue. In our valley rivers, like the Yellowstone, the Madison and the Colorado, for instance, lower flows thanks to less snowmelt result in unhealthy water temperature spikes during the heat of the day.

We’ve seen the “hoot owl” closures in Montana and elsewhere over the last several years — fisheries managers wisely close some rivers to fishing as their temperatures warm beyond the reasonable comfort level for trout. But we shouldn’t wait for a closure to stop fishing — if your thermometer reads anything above 65 degrees, head back to the truck, crack open a cold beer and wait until the evening hatch. Better yet, call it a day, and wait until morning, when the rivers have had all night to cool off.

If you still must fish, head up into the hills, where high-country trout streams can bear the heat. The fish may not be trophy-sized browns or rainbows, but they’ll be plentiful and, thanks to cooler weather, better able to withstand the experience of being caught and returned to the water.

No, it’s not ideal. But even the most zealous catch-and-release angler is likely going to kill trout if they hook and fight the fish when water temperatures have already contributed significant stress to the animal.

Use that thermometer and plan your fishing by degrees. Do it for the trout’s sake.

By Chris Hunt. 

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