The Utah division of wildlife resources has released video footage showing what looks like confetti coming out of the tail of a plane – but look closer and the stream actually contains live airborne fish cascading down into the lakes below.

The footage is from a drop in the state’s Boulder Mountain region earlier this month, and is part of the agency’s annual effort to restock about 200 high-elevation Utah lakes, which are popular fishing spots but aren’t easily accessible by other vehicles.

The fish – which are usually 1in-3in long and include rainbow trout, cutthroat trout, brook trout, tiger trout, splake and Arctic grayling – are specifically raised for fishing. They’re dropped into fishless lakes that don’t have any natural reproduction, and they are often sterile. Utah’s DWR says this allows the state to control their numbers and does not affect any native fish populations.

Utah and other states across the US have been restocking lakes for decades. Before the 1950s, the agency loaded fish into milk cans drawn by horses to remote areas. But it claims that plane drops are much quicker, cost-effective, and “less stressful” for the fish and all parties involved.

The planes, which hold hundreds of pounds of water, fly just above the tree line and can drop 35,000 2in fish in one flight.

The footage shows fish being loaded and dropped into their new homes. In a social media post, the agency said post-stocking netting surveys showed that survival of aerial-stocked fish was “incredibly high”.

“Because the fish are small and released along with water, they easily survive their airplane drop without injury,” they said. “They fall a bit like leaves.”

In 2017, the division biologist Matt McKell wrote about how “tricky” (and dangerous) it is to restock fish in remote bodies of water using dirt bikes and backpacks in what he called “extreme fish stocking”.