A Pond Sits In the Middle of It 

Private ponds make waves in western Montana’s ecosystem

It’s an idyllic picture: a rainbow leaping to take a fly, the flash of color along its sides, the silver splash as it returns to the water—water in your own private trout pond.

Fulfillment of that dream is becoming more and more frequent in the Missoula and Bitterroot valleys, and that is creating a potential nightmare for fishery biologists.

“We’ve gotten almost 50 requests for pond permits in the past year with the majority of the applications in the Bitterroot,” said Chris Clancy, a Montana Fish, Wildlife and Parks (FWP) fisheries biologist. “We don’t see it slowing down anytime in the near future.”

In order to stock a pond with fish, a private landowner must have a permit from Montana FWP. Without the permit, a private citizen cannot purchase hatchery-raised fish.

“When we get a permit request, the first step is an on-site inspection by a local game warden,” Clancy explains. “Based on that written report, we send a biologist out to do an environmental assessment [EA].”

Clancy and fellow biologist Larry Javorsky have done more than four dozen EAs in the past year. They determine the feasibility of a pond and its proposed inhabitants.

“The problem is that each pond needs water running into it and running out of it to keep fish alive,” Javorsky says. “And if water can get in and out, so can fish.”

Inlet and outlet screens are required for private ponds to keep stock fish in and wild fish out. But screens can become clogged with weeds and debris. Pond owners sometimes become impatient with perpetual cleanup and remove the screens, allowing fish to escape.

“We have the same concerns about domestic fish mixing with wild, native populations as wardens concerned about game-farm elk and wild elk,” Javorsky says.

Clancy agrees: “Hatchery fish are pretty disease-free, but the genetic mixing is a serious concern.”

The problem is not as critical in ponds that are requested on the valley floor. Most main rivers and lower streams have healthy populations of rainbow trout, the stock fish of choice. If a domestic rainbow escapes into a rainbow-populated river, no lasting harm is done. However, three recent applications have been for ponds located higher in the mountains and therefore much closer to streams with native cutthroat populations.

“No ponds are allowed directly on live streams, but people divert water and then send it back to the streams,” Clancy explains. “If rainbow escape into a native cutthroat population, they can cross with the cutthroat. We don’t want that kind of hybridization.”

The three high-valley applications were denied, based on the type of fish the pond owners wanted to stock. One refusal was appealed and is being reconsidered, if the pond owner agrees to an elaborate—and expensive—screening setup.

“Screening is the weak link in the chain,” Clancy says.

State fish biologists are working on a number of other options that may help protect wild fish populations from domestic escapees. The state of Idaho has had excellent luck raising “triploid” rainbows, and Montana is experimenting with the same project. By altering the heat and water flow during the egg incubation period, scientists can produce rainbow trout with an extra set of chromosomes. Most of these fish, more than 95 percent, are sterile, which makes them ideal for stocking private and commercial ponds.

“If one of these fish gets away, the chance of it reproducing with the native fish is negligible,” Javorsky says. “It’s a much safer fish to allow in a pond.”

Triploids are also being stocked in high mountain lakes for recreational purposes, Clancy says. Fish that leave the lakes are not a threat to native populations.

The Flathead Fish Hatchery does have stock cutthroat, and the surplus ones can be sold to private pond owners, but Clancy is concerned that the cutthroat there are not genetically the same as the fish found in the upper reaches of the Bitterroot Valley. “We don’t want to change the genetics of these fish,” Clancy says. “We don’t want to lose what we already have.”

Now, the FWP is trying to develop a triploid cutthroat that can be used to stock ponds in areas that have existing cutthroat populations.

“It’s a slow process and the fish are more expensive, but it’s a much sounder choice for the native fish populations,” Javorsky says.

In the Missoula area, applications have been received for a variety of exotic fish as well as trout. Clancy has received applications for bass, perch, walleye, goldfish and koi.

“We never permit walleye. That’s a problem we sure wouldn’t want out here. Koi are a form of carp and we don’t want them either,” Clancy says. “Goldfish can survive in a pond environment, but studies don’t seem to show they cause any impact on local fish.”

If a pond is a closed system and a well or hose provides water, the FWP considers it more of an outdoor aquarium and doesn’t require a permit, Clancy says. Such backyard ornamental ponds are not in the same class with inlet-outlet trout ponds.

“The permits are still coming on,” Clancy says. “People are changing irrigation water rights into recreational water rights. We’re seeing a lot of applications that have no public benefit to them—only risks.”

He adds that there are probably many more ponds out there the department knows nothing about. “It just seems like folks want fish ponds right in their yards,” he says. “I encourage them to go out and fish in the streams instead.”

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