Airplane Trout Stocking

Duane Johnson

Firmly strapped into the only remaining passenger seat of an airplane, barf bag perched at my beck and call, I was surrounded by the precious cargo I had raised all summer in preparation for this very day.  It started out as a gentle flight, but quickly became the wild ride I had been promised. 

Jagged mountain tops towered over us directly out the window as we took our initial dive into a deep chasm in search of our drop zone.  “Let ‘em go!” were the only words the pilot directed at me that early autumn day over the piercing sounds of the low altitude alarms.  As the emerald treetops gave way to cobalt glacier formed lakes of the Sierra Nevada’s western slope, an instant rush of air flooded the cabin when I pushed the lever, opening the door in the belly of the plane.  We pulled out of our dive-bomb and banked hard left, as if avoiding return fire, to look out the window and ensure our payload had hit its intended mark.  An “affirmative” from the pilot to the copilot meant a job well done, and it was off to our next target.

Field and Stream

The peaks of the high Sierra’s, named by Spanish explorers for their resemblance to the teeth of a saw, have limited road access.  Trout stockings in remote lakes, intended to increase recreational angling opportunities, were initiated in the mid 1800s, and painstakingly carried out by barrel carrying mule trains.  Following World War II, an abundance of planes and pilots led to widespread trout stocking by aircraft throughout the Rockies and Sierra Nevadas.

Mule train carrying trout fingerlings for stocking in Idaho circa 1944 (cardcow.com)

Stocking airplanes are outfitted with numerous small compartments that hold trout fingerlings intended for each target, and a final delivery hopper is fed through tubes by switches and levers.  Altitude, shoreline shape, surrounding topography, wind speed, and wind direction must all be accounted for in the approach, and the recent incorporation of Global Positioning Systems has increased target identification and dropping accuracy.

Field and Stream

Although aerial trout stocking created an increase in angling opportunities, concerns are being raised by scientists and environmental groups.  Trout are naturally found below 6,000 feet elevation in the Sierras (below glacial extent), yet most aerially stocked lakes lie above this mark.  Concerns are currently focused on impacts of stocked trout on native fishes, amphibians, zooplankton, and benthic macroinvertebrates at these high altitude locations.  Suggestions center on eliminating stocking in lakes with sensitive native aquatic species and preventing stocking of sites currently void of trout.

Aerially stocked trout contributed to the reduction of endangered mountain yellow-legged frog populations in glacier formed high mountain lakes of the Sierra Nevadas.

One other mistake to avoid is dropping fish on top of people.  On a subsequent stocking flight, another group pushed the lever prior to realizing there was a boat on the lake.  The pilot did all he could to divert his path, but the drop had been made. When the fishy smelling angler called a few days later, my boss questioned, before even apologizing, “How did you get a boat in there?” in hopes we could stock it by truck rather than airplane the following year.

-Patrick Cooney

Videos of airplane stocking (from Field and Stream):

Fish Drop (close angle)

Fish Drop (wide angle)

Fish Drop (from airplane)

Further reading:

Non-native trout in natural lakes of the Sierra Nevada: An analysis of their distribution and impacts on native aquatic biota