The Great Outdoors: Removing INVASIVE FISH SPECIES from Crane Prairie

Website: centraloregondaily.com

The Oregon Department of Fish and Wildlife is making a concerted effort to remove as many brown Bullhead Catfish as possible from Crane Prairie Reservoir.

The goals are to benefit the native Red Band Rainbow Trout Fishery, which anglers come from all over the world to enjoy, and encourage the endangered spotted frog population.

“In 2019 and 2021, we had a smaller effort, but we we trapped over 10,000 pounds of bullhead out in both years,” said Jerry George, District Fish Biologist the Deschutes Watershed. “We are getting good numbers and good biomass of fish out of crane. But it’s one of those things where we think it’s going to take kind of an ongoing, concerted effort.”

What if ODFW did nothing?

“Bullhead are just a generalist predator. And so they tend to upset the balance of these lake ecosystems,” George said. “We’ve had lakes like the Twin Lakes, where we had the trout fishery collapse because of Bullhead introductions in the past. So if they’re not held in check or removed, then they can it can just lead to really poor trout survival and poor trout production of fisheries.”

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Brown Bullhead are the latest in a long list of non-native fish, accidentally or intentionally introduced into the high Cascade Lakes.

Tui Chub and Stickleback Minnows led the invasion decades ago, probably as live bait used by anglers. Later, introductions of largemouth bass, bluegills and catfish likely were placed here by anglers who decided they wanted their favorite sport fish close to home.

Transporting fish is illegal and, in my opinion, amounts to environmental terrorism against native species.

“The non-native fish that have been introduced are either predators of juvenile red band trout or they’re competitors for food resources with Red Band,” said George. “Though, in the case of the Bullhead, they’re kind of direct predators of a Red Band trial fry and Juvenile Red Band. In the case of some of the other species like Bluegill, Stickleback they;re more competitors for food resources. So when you have more species introduced, then there’s just more competition and less overall food for for producing trout.”

For the past few years, biology student interns have been hired to help with the Bullhead control effort. The interns check in empty nets set in the shallows three times a week. They quantify and measure the catch and extract stomach samples from the largest catfish.

“The bulk of our time is spent here, but we’ve done other things,” said Oregon State University student-intern Alex Seibert. “We’ve done electrofishing and stream sampling and macro invertebrates. And so we’re able to apply a lot of these things that we’re learning in classrooms and actually go out and do it physically. And getting paid in the meantime is also pretty nice.”

“We monitor Crane pretty heavily because it’s one of our more important fisheries in the region,” said George. “We do a lot of spawning surveys in the spring to try to understand in particular the number of wild fish that we have spawning in the tributaries, the Crane Prairie. And so we kind of track it through time in terms of spawning numbers and had pretty good spawning numbers in the last couple of years. And so the whole head trapping isn’t kind of a reaction to any decline that we’ve seen. It’s just kind of being proactive and trying to tilt the balance in favor of our native species.”

Crane Prairie is not a good candidate for chemical treatment to remove invasive species because native fish would be killed in the process. Also, this large lake has miles of shallow areas, underwater springs and currents where invasive fish could escape chemical treatment and resume their conquest of the habitat.

“We probably average between like 150-200 a day, I’d say,” said Seibert. “And I can’t do the math that quickly, but definitely in the thousands, but not quite as many as the past few years, which is hopefully a good sign. That means that numbers are getting lower and lower annually. So that’s a good sign of the work that we’re doing, actually being good and helping out the environment around here.”

The public can help by catching and removing as many bullheads and bluegills as they’d like. There’s no limits on them and they are good eating. They just don’t belong in Crane Prairie, where they could ruin one of Oregon’s best trout fisheries and damage a stronghold of endangered spotted frogs.