Science

What’s Going On in That Video of Fish Falling Out of a Plane?

Every question you didn’t know you had about “fish stocking,” answered.

A plane drops fish over a high-elevation lake in Utah
A plane drops fish over a high-elevation lake in Utah. Utah Division of Wildlife Resources

In a video that recently went viral, thousands and thousands of fish go flying out of a plane, over a lake:

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The video, which was posted by the Utah Division of Wildlife Resources, shows “aerial fish stocking,” the practice of dropping fish from planes into high-elevation lakes far below. This month, the state used the method to stock over 200 lakes in hard-to-reach areas, with species like rainbow and cutthroat trout.

Slate spoke with Phil Tuttle, the outreach manager at the Utah Division of Wildlife Resources, about why the fish need to be in those lakes, and how they are likely faring in their new homes. This conversation has been condensed and edited for clarity.

Sofia Andrade: I had never seen anything like this before. Is aerial fish stocking…normal?

Phil Tuttle: Totally normal. I think Utah was kind of one of the first to do it, but it’s been done as early as the mid 1950s. It has been a common practice for more than half a century. And it’s been done by plane mostly because these lakes are actually not accessible by vehicles or other means of stocking because they’re really remote, and they’re really high elevation lakes. There’s not any roads or anything, so we can’t really drive a tanker truck to these water bodies and otherwise stock them.

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A lot of these lakes historically were fishless. They didn’t have any fish in them and they wouldn’t otherwise have fish in them. But we provide a unique opportunity for anglers to go and fish in these areas that are really secluded and beautiful high elevation lakes. That’s kind of why we do it.

Is that the main reason that “fish stocking” is done? To provide fishing opportunities?

That’s kind of the main reason, to provide an opportunity for anglers to go fish. There are other reasons, too. We do stock some fish because they’re native fish and we just try to, like, boost their populations and provide conservation of particular species by stocking them into particular water bodies as well.

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Are there ways to stock fish that don’t involve a plane?

The most common method by far is by tanker truck—a truck that has a big water tank. We raise the fish in a fish hatchery, and then they put those in the truck, and then they take them from the truck to the water body and then dump them just from the truck. But there’s also a few areas where, historically, fish have been stocked by either horseback or on mules carrying big water tanks. But that’s not done as often anymore, partly because we just do by plane for most of those hard to reach places.

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Is there a difference in fish survival rates when fish stocking is done by truck versus by plane?

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Believe it or not, they’re actually really, really comparable survival rates. Anytime you’re, taking fish and sloshing them around in water and trying to get them from point A to point B, there is a level of stress on the fish. If you were like putting them in a water tank, and then putting them on a mule, and then sloshing them back and forth for hours while taking them up a trail and dumping them into a high elevation lake? That actually is a lot more stressful, believe it or not than dumping them out of an airplane. Because you know they’re just put on the plane, and the plane in just a matter of minutes flies to the lake and gets as low as they can down to the water.

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We also make it a point to stock fish that are really small, one to three inches. Since the fish are so small, they literally are almost like leaves. They kind of catch the air and they just slowly flutter down. We estimate the survival as high as 90, 95 percent.

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How are survival rates measured?

We’ve done studies where we’ve had people at the reservoir basically counting dead fish after stocking to see how many are dead. But also, we do netting surveys on the lakes in subsequent years to see what’s there. We’ve found [stocking by plane] to be highly effective and with really great survival. Otherwise we wouldn’t do it, if it was something that’s like, “Oh, you know, tons of the fish die.”

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On social media, a lot of people were concerned that the fish were being dropped from very high up. Could the planes have flown lower?

One of the really important things is we obviously value our pilots and we want them to be safe. So, when they are stocking the lake, it really just depends on the lake. Some of the lakes have a lot of rocks and cliffs and mountains right around the lakes, or there’s trees. Some lakes don’t have very many trees around. And so, depending on the trees, and the surrounding cliffs and rock and that sort of thing, it allows the pilots to get a lot closer.

They would love to drop them from anywhere around 50 feet or less, and that happens most of the time, but depending on the trees and that sort of thing and the obstacles, the safety of the pilots is a key consideration. If you have to drop the fish from a little bit higher — again, the fish are just fluttering down — the survival is still really, really high.

Are there special requirements for being a pilot that stocks fish?

We don’t have training or certifications required for those pilots. However, they’ve been doing it for a really long time. There’s a timing component, right? The pilots need to know when to hit the button that opens the valve that releases the fish, because the fish aren’t gonna live on land. It’s important that those pilots are good pilots, that they’re safe, and that they are able to have the timing right to release those fish into the water.

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