Fisheries experts urge caution when temperatures rise | Status

CASPER – The numbers are overwhelming.

The Encampment River in southeast Wyoming normally flows at about 900 cubic feet per second in late June. That year it was 125 cfs and sinking.

Only 43% of the normal amount of water flows from the mountains into the Fontenelle Reservoir in southwest Wyoming.

The Green River typically has between 2,000 and 10,000 cfs this time of year. Right now it’s around 700 cfs. The Green River, which flows through the city of the same name, had reached 75 degrees during the day and fell again at night in the high 60s in mid-June.

“None of these temperatures make trout happy, but they can survive them. But when you get 80 and older, they can get lost, ”said Robb Keith, Green River Fisheries supervisor for the Wyoming Game and Fish Department. “Your physiology is not designed to handle this warm water.”

If water temperatures are kept in the 80s, trout will die.

The warm water temperatures and low water levels are partly due to a historically hot June, but also to a low snow cover in winter and little moisture in the last few months.

Typically more than 2.5 inches of rainfall falls on Rock Springs between April 1 and late June. This year residents have seen just over half an inch, said Chris Jones, a meteorologist with the National Weather Service in Riverton.

The rest of the summer forecast into autumn is no better.

“And unfortunately, in the hot, dry conditions we started in, those conditions are self-feeding,” said Jones. “The floors are dry, and without moisture the temperatures get warmer and that nourishes them and it can be a little harder to overcome.”

What does this mean for anglers who are still hoping to make the most of this unusually hot summer? Be aware of river and lake temperatures, fisheries experts said, and in many cases, get creative.

Most fishery biologists recommend that you stop catching and releasing fish when river temperatures hit the high 60s or 70s. While these temperatures don’t kill trout instantly, trout have a much harder time using energy pulling out of the water, fighting a line, pulling it up for a photo, and putting it back in again.

“The fish they catch have to break down the lactic acid they built up in battle, and they have a hard time doing that when the oxygen levels drop,” Keith said.

Anglers who itchy to get on the river can go early in the morning when the temperatures are cooler.

Lakes and reservoirs are sometimes no different. Fish like lake trout and kokanee struggle to survive when dragged from 45-degree water near the bottom of reservoirs through 70 or 80-degree water near the surface, he said.

“People release them and in the end you have floating kokanee,” he added. “When you reach your three-fish limit, hold it and stop fishing or fish for lake trout puppies or rainbow trout.”

When a river allows you to hold fish, catch your limit, put them in the cooler, and head out, said Nick Walrath, Green River Project coordinator for Trout Unlimited.

And remember to bring a thermometer with you so that you can check the temperature of the water if in doubt.

Just because the rivers are warm and lakes are dangerous for salmonid fishing doesn’t mean you have to stay home.

High mountain streams are likely still cool enough to catch and release them, Keith said. You can also consider fishing for fish like brown trout in high mountain streams and sticking to your limit for a fish meal or two.

Or do you think about targeting other species, Walrath said. Visit places like Flaming Gorge and throw carp on the plains. They are big and fight hard.

As Keith worries about additional pressure on trout from anglers, the angling becomes more difficult. Moss has formed and is floating down the Green River under the Fontenelle Reservoir, making fishing difficult. Trout are also more likely to cower in deep, cooler pools of water with suppressed appetites.

Low runoff also means less ash and soil will be dumped into the upper North Platte River after last summer’s historic Mullen Fire, said Bobby Compton, Game and Fish’s Laramie area fisheries inspector. Massive ash runoff and erosion in rivers can also kill large numbers of fish.

Ultimately, prolonged drought and increasingly warm temperatures are compounding the need to work on river restoration and reconnection, Walrath said. The healthier the stream – with fewer culverts and less erosion – the better species like trout can survive in a changing climate.

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