Stressed fish

A Brown trout. (Photo by Philthy54/Wikipedia)

This weekend marks the unofficial start of the summer season. It’s wonderful news for festivalgoers and outdoor recreationists in the high alpine — and terrible news for trout. 

Fish are stressed right now: earlier this week, Colorado Parks and Wildlife enacted an emergency fishing closure “due to critically low water flow caused by dry conditions and minimal snowpack levels” on a half-mile stretch of the Yampa River farther north in the western part of the state (near Craig).

Should the flow rate improve “substantially for a continuous period of time” — due to big storms, which are not in the forecast — “CPW will re-evaluate the emergency closure,” Senior Aquatic Biologist Lori Martin said in a press release. “But because of the current conditions, we need to take this action now.” When water flows are minimal, the release noted, “fish become concentrated in residual pool habitat and become stressed due to increased competition for food resources.” That leads to another problem: “The fish become much easier targets for anglers, an added stressor that can result in increased hooking mortality.”

Goose Bennett, the head guide for Telluride Fly Fishers, said local rivers are not as imperiled as that stretch of the Yampa. 

“Right now, we’re not in terrible times, but we’re also not in great times,” Bennett said. “A few years ago, when we got very little snow over the winter” (which resulted in very little runoff), “that was terrible.”

Bennett, whose college degree is in fish biology, has been guiding for more than two decades in the mountain west and Alaska, offered a description of what being a stressed fish might feel like when it is caught and released. “Imagine getting the wind knocked out of you” — the catch and release part — “and then putting your mouth into a paper bag and trying to breathe” (as you are returned to oxygen-depleted waters). 

“That fish will swim off and look like it will be completely fine,” Bennett went on. “And within an hour, it’s floating down the river.”

Even a small degree difference in altitude, and sun exposure, can make big difference to a fish’s stress. “It’s lower in Placerville” than up-river, Bennett pointed out. 

“As the sun hits the water, it warms it. And as the water rolls over sun-exposed rocks,” the warming effect is compounded. Warmer water can be especially deleterious to certain species (“A Brook trout wants cooler water,” Bennett explained, “while a Brown trout can tolerate heat.”)

“In July, we expect thunderstorms. It’ll cool down the river,” Bennett added. “If we get some decent rain,” warmer water and lower flowers “won’t be as much of a problem. But if we don’t get more rain, August in particular will be tough. Going into September, it will start to cool off again. It’ll still be low water, but temperatures will go down, so we won’t harm the fish as much. 

“It’s fine to go out all day at that point.”

Which implies that right now, it is not. 

“I watch the water temperatures,” Bennett said simply. “When it starts to get into the high 50s and low 60s, we don’t fish. I literally say ‘No’” to clients who might ask.”

Bennett is happy to take folks fishing (he is a guide, after all) but he offered to a suggestion to those who might want to go alone: purchase a water thermometer. “I can stick my hand in the water and tell what the temperature is,” Bennett said, “but for new anglers, my advice is to purchase one of these thermometers. They’re encased so they don’t break, and you can attach them to stuff.” The thermometers cost about $10.

Bennett offered one more suggestion to catch-and-releasers concerned about not stressing fish: get your catch back in the water quickly. “You don’t want to play the fish for too long,” he said. “Get it released and back in the water as soon as possible.” Indeed, from the moment Bennett pulls a fish out of the water to remove the hook until he releases it again, “I hold my breath, because the fish is, too,” he said. “It’s only fair, right?”

For more information on fishing Colorado, visit CPW online at Telluride Fly Fishers has been offering guided trips in this region for 30 years. Learn more at or by phoning 970-728-4440.