How thousands of live fish drop from planes every year in Utah — and survive

Utah has been aerially stocking high-elevation lakes with fish since 1956.

(Francisco Kjolseth | The Salt Lake Tribune) The Division of Wildlife Resources introduce around 40,000 splake, a sterile cross between lake trout and brook trout, into the Jordanelle Reservoir on Thursday, June 21, 2018. Measuring four to five inches long, splake will quickly grow and could reach adult lengths of more than two feet long as part of ongoing management plans at the reservoir that currently holds numerous other fish species.

It’s not a bird, but it is a plane … and it’s dropping thousands of live fish.

The Utah Division of Wildlife Resources performed its “annual aerial fish stocking,” at high-elevation lakes in southern Utah on July 6, a process that has been used in the state since 1956. More than 200 Utah lakes are stocked this way each year, with tiny fish fluttering down from heights they will never reach again. But this year, as the state confronts a severe drought, some bodies of water are not receiving as many fish.

In an effort to decrease the number of fish that may die due to low water because of drought or maintenance work at certain lakes, Utah Division of Wildlife Resources Sportfish Coordinator Randy Oplinger said stocking has decreased from previous years.

“We are not entirely cutting the stocking of any waterbody, and if we decrease the number of fish stocked into one lake, we will reallocate those fish to another waterbody where we don’t anticipate low water levels,” Oplinger said in a news release. “Also, these anticipated stocking changes only impact 1–2% of the lakes and reservoirs in Utah and don’t include any of the major fisheries.”

Up to 35,000 young fish — called fingerlings, since they are only 1-3 inches long — can be dropped in a single flight. The fish that are stocked aerially are most commonly rainbow trout, cutthroat trout, brook trout, tiger trout, splake and Arctic grayling, and they are put into usually fishless lakes that don’t have natural reproduction or are inaccessible by vehicles.

“They fall a bit like leaves,” according to the Division of Wildlife Resources, with their small size slowing their fall and allowing them to make the drop safely. The survival rate is “very high,” according to the division, which uses netting to survey each drop, sometimes within minutes.

“The pilot flies just barely above the trees to drop the fish. There are often cliffs, mountains, tall trees and other obstacles that determine how low the pilot can fly. The safety of the pilot is a key consideration,” the division stated in a news release.

Many of the lakes are not accessible through road transportation, but even if the division were able to, aerial stocking would still be more cost-effective.

“The plane has seven separate tanks that can drop fish into seven lakes in one flight. It is actually a very cost-friendly method, considering that we can drop up to 35,000 two-inch fish in a single flight, without reloading fish,” the press release says. “We can aerially stock 40–60 lakes in a single day.”

The process is easier on the fish, too.

“Fish are more stressed when transported by ground because it is difficult to maintain their required oxygen levels in small, packable tanks for such long distances,” the division said.

The fish are acclimated to the temperature of the lake they will be dropped into before being loaded into the plane, which is “fitted with a large tank that can hold hundreds of pounds of water and up to 70 pounds of fish.”

The fish are stuck with a first-class flight, for now; an unmanned trip to Utah’s mountain lakes isn’t ready just yet.

“A drone that has the ability to hold that kind of mass is not currently available to us,” the division stated in a release.

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