The Environmental Impact of Stocking Non-Native Fish for Sport Fishing

Heads up. This is Andrew. He's responsible for releasing fish into this river. But there's a catch. These fish aren't from here. They're not native to this river. And until the late 1800s, they never would have been found here at all. So why are they being released here by state officials? Well, it turns out there's a very real but kind of counterintuitive reason for this. There aren't a lot of fish thriving in ecosystems like this one. So in order for people to enjoy the sport of fishing, they need to put fish into the water.

It's a process called fish stocking, where fish are bred and released into the wild, often for the specific purpose of being fished out. It's done all over the country using trucks, hoses and even planes. For our trout stocking program the goal is for 100% of the fish to be caught. So they're being bred in hatcheries to be caught? That's right. Which does raise a big question for me. Is it reasonable to raise fish for the sake of sport? And what's the effect on the ecosystem that these fish are dropped into? So I came up here to Connecticut to see some fish stocking in action and find out more about why this is such a common practice.

And so there's a little ball at the bottom of the net. You can grab that, get close to the water's edge. You just kind of toss them out. Does that make sense? And then we want to keep them out of the air, too. Which is why we're running right? When I started learning about fish stocking, I was like, wait a second. Are states actually just putting invasive species into the environment, while at the same time they have programs to fight different invasive species?

Fishing is very important to conservation funding in Connecticut. About 170,000 people participate in fishing each year in the state of Connecticut. When they buy their fishing license, all of those funds go back to fisheries to fund conservation efforts, to fund stocking, to fund fish habitat. Nationally, fishing licenses and taxes on fishing equipment like rods, tackle, and even boats combined for well over $1 billion in conservation revenue in 2024. Ironically, to support all this recreational fishing, the state has to manually put fish back into these waters, because, well, there's just not enough fish there anymore. So non-native fish are bred in hatcheries like this one.

Connecticut has three hatcheries, but there are hundreds in the U.S., So what kind of fish are we stocking today? A few different trout species. There's going to be rainbow trout. Brown trout as well. And that's where this gets tricky, because rainbow trout come from the west coast of the US and brown trout actually come from Europe, Asia, and Northern Africa. We have been stocking fish in the US for more than 100 years. It dates back to the 1800s. In the late 1800s as the US built dams and polluted waterways native fish disappeared from lakes and streams all over the country. So the federal government

began raising fish in hatcheries and shipping them across the US. And they did this using fish cars, which is yeah, literally just trains full of live fish. And they used horses or mules carrying the fish in buckets to get them to the water. The term "invasive species" hadn't even entered into like the, the conversation whatsoever. I'm not even sure there was invasion biology as a science, but we were bringing fish both to the west coast, from the east coast and vice versa. But today, we have a much better understanding of the havoc that some non-native species can wreak. And we're still stocking fish.

Just using trucks and planes instead of horses. And humans also play a role in disturbing their natural ecosystems. Streams are getting hotter. So warmer temperatures, it's not great for a cold, a cold loving fish like trout or salmon. Dams have been maybe the number one habitat problem for these different species, especially migratory species like salmon and trout. And here on the Mianus River in Connecticut, there are several dams that affect the native fish population. And of course, it's important to clarify that Connecticut isn't just throwing fish into its water at random. If you go back to say the 1870s when the Connecticut Fish and Game Commission was first established, and you see those early years of stocking

there, introducing all sorts of fish into all sorts of places, and some of those have had really deleterious negative effects. And so there are these potential negative effects, but that's why we do monitoring, right? That's why we it's an adaptive management process where we're out collecting data, following up and doing evaluations to make sure we're not having those issues. But even with the most careful approach, things can go wrong. When you have a foreign fish that you're putting into the environment that doesn't belong there or didn't evolve there, it can displace the native species.

Non-native stocked fish are raised in hatchery conditions and in a hatchery they learn to become aggressive. And then when you put those stocked fish into the environment, they might be better at finding food or outcompeting the native fish. And there are some more complicated consequences, like the phenomenon known as hybridization, which is when non-native fish breed with the fish that evolved to live there. They start breeding with a different species that evolved elsewhere, they might lose some of those genetic traits that help them survive, and that can actually lead to the declines of those native species. And of course, there's a very real welfare concern

of what it means to be breeding these fish in hatcheries, to then be caught. Is this good for the life of a fish? Like, definitely, definitely not. Like, I think that's pretty clear. I know it looks like it's just me out here, but reporting stories like this one takes a whole team. Editors, fact checkers, animators, journalists all working together to tell a story that's nuanced, accurate, and fun to watch. And if high quality, independent journalism is important to you, then you would love our Vox community on Patreon.

For a few dollars a month, you can get access to exclusive videos, new shows were developing, and a chance to chat directly to journalists. And if you're not able to support us financially right now, then you can follow us on Patreon for free to stay connected and find out what we're up to next. Now back to the video. Beyond the potential ecological impacts, fish stocking points to a larger problem. We're in a moment of compounding climate and biodiversity crises. And how we protect wildlife matters more than ever. So practices that may have seemed okay historically, like stocking fish for recreation, can now critically undermine ecosystem resilience.

This is really about whether our public institutions are set up to protect wildlife for the long term. States prioritize non-native fish because fishing is such a big part of their revenue. It comes down to funding. The perception that hunters and anglers are the sole bread and butter creates this built in incentive prioritize a few game species and, you know, stocked fish species. The resources currently dedicated to raising hatchery fish and stocking our lakes and rivers with them could be better spent on those other sources.

It's this strange paradox at the heart of this. In order to fund conservation, states end up having to do something that, at least in some cases, hurts the very ecosystem they're trying to conserve. This is ultimately a systems problem. How we fund and define conservation. And that's what needs to evolve. So diversified funding streams are really important. In Oregon, they just passed legislation, to increase a lodging tax, and that money would go towards their state wildlife action plan and their list of species of greatest conservation need. And other lawmakers have floated the idea of a backpack tax, which would tax outdoor equipment the way fishing is.

We would support diversified funding streams. Absolutely. Anything that's going to increase our capacity to conserve fisheries would be awesome. I do think that states are in a tricky position. They have constituents who want to fish, and they also have constituents who want to conserve nature, which is also part of their mandate. I think that there's, a false tension that you can envision there where it's as if we are stocking fish and managing sport fish instead of conserving species. When we stock fish, that gets people to go out fishing to engage with the resource, build political

will and build the economic capacity to support non-game fish too. The point that I think should be emphasized is that getting people out into the environment might build an environmental ethic or a conservation ethic that ends up providing a net good. Ultimately restoring native systems and the fish that live in them would be a clear win for everyone.