Airborne fish aren’t native to the Colorado Rockies, but in recent weeks about 125,150 lucky swimmers have learned what it feels like to fly — at least for a few seconds.
The fish have been plummeting out of planes all over southern Colorado as part of the annual aerial stocking effort conducted by Colorado Parks and Wildlife (CPW), the agency charged with maintaining the state’s fish populations.
Aerial stocking, with helicopters and Cessna 185 airplanes, is used to drop fish into the state’s high mountain lakes that are virtually inaccessible by foot or horseback. The program targets more than 600 lakes across the state, many of them at elevations of between 10,500 and 12,000 feet.
Aside from insuring that backpackers and other backcountry travelers will have fish to catch, stocking remote high mountain lakes can help establish isolated populations of fish for scientists to draw on in case the need to breed them should arise.
Plane drops are a mere subset of the state’s annual stocking effort, which will put more than 53 million fish into Colorado waterways this year alone. According to CPW figures, fishing is second only to skiing as an economic contributor to Colorado’s recreation economy, contributing around $1.2 billion annually. Maintaining that moneymaker takes a lot of work.
Last week, the Garfield County Airport was at the epicenter of aerial stocking efforts in the state, as three pilots used the Rifle runway as a base to stock 265 high alpine lakes in western Colorado. This week the pilots will head to Salida, Gunnison and Durango to stock lakes high in the San Juan mountain range, according to Mark Jimerson, assistant manager at the Rifle Fish Hatchery.
In Colorado, aerial stocking typically takes place in the late summer or early fall, when high-altitude lakes are mostly thawed out from the previous winter.
“I don’t like bouncing them off the ice,” said Al Keith, a Colorado Springs-based pilot and one of four who handle the bulk of aerial fish stocking across the state.
The pilots alternate each year between stocking southern and northern Colorado, which is much wetter. Last year, according to Jimerson, the pilots stocked 422 northern Colorado lakes.
The typical aerial stocking operation begins between 5 a.m. and 6 a.m., before the winds begin to pick up as afternoon temperatures rise.
Stocking planes are equipped with rear-mounted square aluminum tanks that can hold up to 10 species of fish in separate cylinders. On the tarmac, fish are transferred from stocking trucks to the “hoppers” in the rear of the plane. Oxygen is piped into each cylinder, to keep the fingerling fish alive during flight.
Fish being stocked typically measure between 1 inch and 2.5 inches long; any smaller and they won’t be able to survive in the wild. Any larger, though, and the impact of their bodies hitting the water could be deadly.
“They drop them from fairly high up, so that the fish will go in nose first and break the water’s surface,” Jimerson said. “The lowest that they would drop fish would be about 20 feet over the lake.”
“You don’t want to slam them into the water,” said Larry Gepfert, who has been a CPW stocking pilot for 12 years. “About 300 feet is as high as you’ll go. The idea is to drop them high enough so that a column of water can form and break up the impact, but not so high that the column of water dissipates.”
Over most lakes, the fish are dropped when the plane has slowed to around 85 miles per hour. The pilot flips a switch to open the trap door to release the fish.
“I have my trip switch right under the throttle, so it’s easy to reach,” said Keith.
After the drop, a pilot must veer quickly away from the lake. This can be tricky, since high alpine lakes are often small — sometimes it involves pulling up quickly to avoid trees on the shoreline, or veering off into a canyon below.
Stocking can be particularly harrowing with high winds in the picture. Both Gepfert and Keith earned their stripes working as bush pilots in Alaska, and both are familiar with windy conditions. But the men say that a good gust of wind can suck the fun right out of an otherwise pleasant flight.
“There have been times for me where the pucker factor has been up there pretty high,” said Keith. “After a while all of the lakes get to be normal and pretty routine, but if you’ve got some pretty high winds blowing, they are all tough to do.”
In 2002, a CPW pilot was killed and the biologist traveling with him was injured when his plane hit a sharp downdraft of wind just above a lake near Salida.
Today, pilots nearly always fly alone on stocking trips, which can last up to six or eight hours, depending on the weather.
“With four of us working, we can do around 100 lakes in a day,” Gepfert said.
Despite the danger, Keith said he loves flying stocking planes, particularly in the mountains around Telluride and Silverton in southern Colorado.
“I like seeing all the trails up there, and people using the resources,” he said. “When we’re flying, we see people on top of mountains, on top of fourteeners. I hope we don’t ruin their wilderness experience.”