Oregon chub: Swimming against the current

The U.S. Fish & Wildlife Service was expected to announce today that it plans to submit a formal delisting proposal for publication in the Federal Register, marking the first time an endangered fish has ever been declared fully recovered.

“We’re pretty excited about it,” said Paul Henson, the federal agency’s state supervisor for Oregon. “It’s great validation not just for the work we’ve been doing here in Oregon and the Willamette Valley but for the Endangered Species Act itself.”

Once found in shallow floodplain environments throughout the Willamette Valley, the Oregon chub was in sharp decline by the early 1990s as its habitat fell victim to flood-control projects, agriculture, urban development and predation by introduced game fish such as bass and bluegill.

In 1993, when it was added to the Endangered Species List, there were fewer than 1,000 chub left in eight known populations.

“This is a uniquely Oregon fish. ... It’s found nowhere else in the world,” Henson said.

“It’s not the biggest, most charismatic or iconic fish, but it’s a special fish for Oregon and the valley and it plays a unique ecological role. It’s a food fish for a lot of other species.”

By 2010 the species had bounced back sufficiently to be downlisted from endangered to threatened, and today there an estimated 160,000 chub in 78 distinct populations along the Willamette River mainstem, the Middle Fork Willamette, and the McKenzie and Santiam rivers. Some 23 of those populations contain at least 500 fish and have been stable or growing for at least seven years, more than enough to meet the federal criteria for delisting.

“I’m elated that we are where we are now. I never anticipated we would get there so soon,” said Paul Scheerer, an Oregon Fish & Wildlife Department biologist who led the chub recovery program for much of the past 20 years.

ODFW partnered with the U.S. Fish & Wildlife Service, other state and federal agencies, private landowners and nonprofit conservation groups in the recovery effort, which included introducing the fish in areas where they had disappeared or had not been known previously, restoring habitat and re-establishing floodplain connections .

Brian Bangs, another ODFW biologist working on chub recovery, noted that most of the current numbers — 110,000 out of 160,000 fish — represent introduced populations. But studies of dye-marked chub have also shown that the diminutive minnows can travel three miles or more in the quest for new feeding and rearing grounds.

“Since 2010 we’ve found chub in lots and lots of places we never knew they were before,” Bangs said. “We’re seeing them colonize new habitat.”

State and federal wildlife managers give a large share of the credit for the chub’s comeback to private landowners who agreed host fish populations in exchange for safe harbor agreements shielding them from additional land use restrictions as those populations grow.

“You need proactive incentives for recovery and not just regulation,” Henson said. “You need to ask people for their help and not just tell them what they can’t do.”

To make sure the comeback continues, a post-delisting monitoring plan has been prepared to keep tabs on chub numbers for the next nine years.

The species may also benefit from ongoing floodplain restoration efforts in the Willamette Valley, as well as a new water-release policy for U.S. Army Corps of Engineers dams in the region designed to mimic natural flow regimes.

“This is a fish that’s a floodplain fish,” Scheerer pointed out. “They move in and out of river systems, and their habitats are formed by river processes.”

Scheerer acknowledges that most people have never heard of the Oregon chub and are unlikely to get too excited about its recovery. But he thinks the tiny minnow’s removal from the Endangered Species List is something everybody — not just fish biologists — can celebrate.

“It’s certainly not a keystone species — I don’t think anyone would call it that — but it is an indicator of (floodplain) habitat,” Scheerer said.

“If the chub are doing well, it means these habitats are doing well — and lots and lots of species use these habitats besides chub.”

Contact reporter Bennett Hall at bennett.hall@gazettetimes.com or 541-758-9529.