Monday, June 14, 2010

Biologists find big trout during Flaming Gorge Surveys

Dutch John -- Freezing temperatures and rising winds couldn’t keep Matt Breen and Calvin Black from breaking out in a big grin.

As they pulled the first lake trout out of the water that day, they knew the fish was a monster.

And was it ever: it weighed more than 29 pounds!

The two Utah Division of Wildlife Resources biologists were helping Ryan Mosley set and pull nets on the first day of the annual fisheries survey at Flaming Gorge Reservoir last May.

Mosley is the UDWR’s aquatic project leader at Flaming Gorge. Based on years of data, he and the other biologists say fishing should be good at the reservoir this year.

“The data hasn't been summarized [yet], but this year's catch shows a healthy population for anglers to target this fishing season,” Mosley says.

Mosley says rainbow trout were well represented in the nets. Many of the rainbows pushed 20 inches in length. They weighed about three pounds each.

“We also sampled 37 fish in our lake trout nets,” he says. “The fish looked good. The largest lake trout weighed 29.1 pounds, which is about the threshold the nets can handle.”

Mosley says the water in mid-May was too cold for smallmouth bass to show up in the nets.

So what are his recommendations for this year?

“Come out and enjoy the great fishing at the Gorge," he says. “The person who coined the phrase ‘Money can't buy you happiness’ never bought a Utah fishing license!”

Mosley also encourages you to take a limit of lake trout and smallmouth bass home with you. Reducing these predators will help the reservoir’s kokanee salmon, lake trout and smallmouth bass fisheries.

Also, please remember that you must kill and keep all the burbot you catch.

Trend netting
Since fish don’t voluntarily rise to the surface whenever biologists need to see them, researchers use a variety of techniques to catch fish so they can study them.

One of those techniques involves catching fish in nets.

“Gill netting has been used as a fisheries monitoring tool on Flaming Gorge since 1965, three years after it began filling,” Mosley says. “[The gill net monitoring] is a coordinated effort between the Utah Division of Wildlife Resources and the Wyoming Game and Fish Department.”

Although the methods biologists use have changed a little over the last 40 years, they still sample at the same sites, using the same type of nets and sampling at the same time of the year.

These standard procedures remove variability from the data they collect.

UDWR biologists currently sample at 10 sites. The sites extend from the Green River arm at the head of the reservoir, all the way down to Jarvies Canyon, about five miles from the dam.

Biologists set the nets each May when the water temperature reaches about 50 degrees Fahrenheit.

Comparing the results of a capture technique over time allows biologists to detect trends they may not see if they looked at data only from a single day. These trends include the size of the population, the health and condition of the fish and what the fish are eating.

Depending on these trends (and other trends collected using additional sampling tools), managers can make changes to address potential concerns. “For example, biologists observed an increase in the abundance of lake trout back in the 1990s and early 2000s,” Mosley says. “Unfortunately, they also noted a severe decline in the Utah chub population and a corresponding decline in [the number of kokanee salmon.]”

As the Utah chub declined, Mosley says the lake trout in Flaming Gorge started eating kokanee salmon. To address this population imbalance, the lake trout limit at the reservoir was liberalized.

The current regulation, which dates back to 2006, allows anglers to keep up to eight lake trout. But only one of those fish can be longer than 28 inches.

For more information about fishing at Flaming Gorge, call the UDWR’s Flaming Gorge office at 435-885-3164.

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