Division of Wildlife
DOW PILOTS STOCK HIGH-ALTITUDE LAKES WITH TROUT
Wildlife precision pilots equipped with GPS-enabled aircraft drop
trout fingerlings into dozens of fishing holes across Colorado’s high
country. The state’s fish restocking program resumes just before one-year
anniversary of crash that claimed the life of veteran wildlife biologist and
pilot Jim Olterman.
Colorado Division of Wildlife (DOW) pilots recently completed this year’s
mission to restock trout in hundreds of high-altitude lakes used by anglers
who prefer to hike up rugged backcountry trails to remote fishing spots.
The pilots stocked nearly 300 lakes between Aug. 26-Sept. 12, flying with
skilled precision into mountain regions to drop greenback and Rio Grande
cutthroat trout fingerlings into lakes.
DOW pilots this year stocked lakes in the Colorado, Rio Grande and North and
South Platte river drainages, dropping nearly one million trout fingerlings
into high lakes along the eastern and western slopes.
This year’s mission was poignant for wildlife pilots Al Keith and David
Younkin, who lost a friend and co-worker on Sept. 4, 2002.
Veteran terrestrial biologist and pilot Jim Olterman, 57, died when the
single-engine Cessna 185 he was piloting crashed onto a remote ridge in the
Sangre de Cristo Mountains southeast of Salida. His passenger and co-worker,
Brandon White, survived. The men were en route to a lake during a stocking
mission. DOW suspended flights following the accident. Investigators believe
strong crosswinds may have contributed to the crash.
Each year, Colorado biologists assess the need for trout in high-country
lakes before determining whether to restock them.
Four Cessna 185 airplanes equipped with global positioning technology and
aluminum fish tanks enable wildlife pilots to airlift trout fingerlings and
drop them into lakes that are too difficult to reach over land. GPS
equipment enables pilots to chart the most direct route from lake to lake.
Biologists say the flights are the most cost-effective and humane way to
transport fish to high-altitude lakes. Alternatives include carrying fish up
to lakes on mules or in backpacks, a labor-intensive approach that does not
guarantee that all lakes will be stocked or that all fish will survive the
By airlifting fish, pilots can stock as many as 70 lakes per day, depending
on weather conditions, and fish survival rates are very high. According to
recent studies, 95 percent of fish dropped into lakes survive the aerial
stocking. In addition, the estimated cost of stocking each lake is a modest
“In just a couple of short weeks, they’ve stocked what would have literally
taken us months to do. And we likely wouldn’t get it all done,” said senior
aquatic biologist Steve Puttmann. “That’s the advantage of using these
This year’s crop of trout fingerlings will take up residence with several
generations of fish planted by wildlife pilots in recent years.
Most of the lakes stocked by wildlife pilots are above 10,000 feet.
Restocking provides fishing enthusiasts with quality outdoor experiences in
pristine environments and helps in the recovery of threatened native fish
species. The greenback cutthroat trout is a state and federally listed
threatened fish and the Rio Grande cutthroat trout is a state species of
special concern, said Doug Krieger, a DOW senior aquatic biologist.
The restocking program started in the 1950s, but was halted in 1994 due to a
lack of pure sources for fingerlings. Fisheries and natural populations were
hit hard by whirling disease. Re-establishing disease-free hatcheries has
been a prime goal of the DOW. Restocking resumed on a small scale in 2001
and on a major level in 2002.
“We get a lot of backcountry pressure from fishermen. It’s one of the truly
unique fishing experiences you can have in Colorado—if you want to catch the
native trout that evolved in Colorado and were found in the rivers and lakes
when settlers entered the region in the early 1860s,” Puttmann said.
By necessity, the professionals who stock Colorado’s high-altitude lakes are
skilled, precision pilots who fly under unique circumstances. Reaching the
ponds—many of them in volcanic cirques surrounded by giant conifers—often
requires them to negotiate dicey flying and weather conditions. Small
airplane engines are less efficient at higher elevations. Pilots must fly
into narrow valleys, turn around and fly out.
“The radius around those lakes is very confined. They are surrounded by high
peaks and cliffs,” said wildlife pilot David Younkin. “We do some tight
turning and very abrupt descents. And we rarely have the optimum situation.”
Puttmann acknowledged that wildlife pilots involved in lake restocking
missions have perilous jobs.
“As we all saw last year when we lost Jim, this is extremely dangerous
work,” he said. “And these guys have done this flawlessly this year.”
Younkin has flown 11,000 hours for the DOW since 1986. He learned how to fly
while growing up on a western Nebraska ranch, piloting into town for
equipment parts and checking on ranch fences and livestock. He later
shuttled government personnel to airports across the West during
construction of Minute Man missile silos. However, nothing prepared him for
his restocking flights.
“The one thing I’ve learned in fish plants: You have to unlearn a lot of
things you learned about mountain flying,” Younkin said.
Wildlife pilot Al Keith has logged 1,700 hours for the DOW in three years.
Born in New Mexico, he learned how to fly in Washington’s Cascade Mountains,
where he flew search-and-rescue missions, and has flown in Alaska.
Keith admires that Colorado residents don’t shy away from the state’s
backcountry. When he arrived in the state, he noticed how many residents
enjoy fishing, hiking and climbing, especially up and down the state’s
plentiful “fourteeners” – mountains that are 14,000 feet or higher.
“I loved Alaska, the flying there, the beauty of the mountains. But most of
it is inaccessible,” he said. “I love flying over fourteeners (here in
Colorado) and seeing climbers up there. I dip my wings to salute them.
Colorado does not take a backseat to Alaska in that area. I think we’re in
Meanwhile, Younkin downplays the inevitable cowboy imagery that arises when
others hear of pilots’ efforts to restock Colorado’s mountain lakes. He said
the crash that claimed his colleague’s life was a tragic accident. He and
fellow wildlife pilot Alvin Keith work in tandem, backing each other up via
“The judgment you have to use not to extend yourself into a dangerous
situation is always the highest priority,” he said. “These are well
Without a doubt, wildlife pilots and biologists play a vital role in
satisfying the demands of high-altitude anglers who trek up steep mountain
trails to camp and fish.
“You’ve got to be committed to those lakes. We have a lot of outdoorsmen who
use them to various capacities,” Younkin said.
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