Oregon chub found in the Molalla River basin
An ODFW Native Fish Investigation team has found the first Oregon chub to be found in the river since Eisenhower was president.
Biologists from ODFWs Native Fish Investigations Program recently teamed up with the Molalla River Watch. The result – the first sighting of Oregon chub in the lower Willamette basin in 60 years.
Last month, the NFI biologists discovered two populations of the threatened native minnow in the Molalla River Basin, the first to be seen in the river since Eisenhower was president.
Historically, Oregon chub occupied the Willamette River from the mouth of the Clackamas to the Coast Fork and Middle Fork of the Willamette River. The last observation of these fish in the lower Willamette, however, was in 1953 at Oregon City.
Oregon chub were one of those things we have been looking for a long time, said Brian Bangs, an ODFW biologist working on native fish investigations. Biologists at OSU were looking to find populations up there in the Molalla. And then in one day in September, they found Oregon chub in two separate areas. We thought the fish were gone, so this is fantastic.
The tiny fish were found in Milk Creek near the Canby-Mulino Bridge and in Feyrer Park near Molalla. Oregon chub had not been documented in the Molalla basin previously, he said.
Since 1991, ODFWs Native Fish Investigations Program has conducted surveys at more than 50 locations in the lower Willamette in an attempt to locate this species, without success.
Then in 2013, NFI partnered with the Molalla River Watch to identify and survey additional locations in the Molalla River basin. Bangs said Kay Patteson of Molalla River Watch worked with biologists during the investigation.
Oregon chub thrived in off-channel habitats such as beaver ponds, oxbows, backwater sloughs and flooded marshes. But nonnative fish species, such as largemouth bass and bluegill, devour the tiny Oregon chub, and are common in the off-channel and slow flowing habitats preferred by the chub.
The chubs defenses are to dive into vegetation and hide, but thats the same area the bluegill and bass hunt, he said.
The impact of nonnative fish, combined with the alteration or loss of many off-channel habitats and changes in river flow due to the construction of the Willamette dams, led ODFW biologists to believe that Oregon chub were completely killed off in the lower Willamette.
Now, this Molalla basin finding extends the range of Oregon chub 70 river miles north. Although populations were historically documented below Willamette falls, the current known distribution is close to the historical distribution of Oregon chub.
The Molalla basin has a lot of alluvial flood plain that people have not destroyed yet there are no dams on the Molalla its a natural system, Bangs said. So I got interested in surveying the system and talked to Kay. She got me information and helped my motivation to get going on this.
Bangs said a big problem in finding Oregon chub is that they hide out in aquatic vegetation.
There is a lot of river out there, and we are talking about a minnow thats an inch and a half long, he said. So with all those streams, its a needle in a haystack.
Bangs joked that the world record Oregon chub measured about 3 and one-half inches. But the chub are important to the sustainability of Oregon rivers. Being tiny, they are low on the food chain, and are a food source for trout and salmon at least they were, before the bass and crappie moved into the river basin, he said.
But with this find, Oregon fish biologists are feeling optimistic.
Even though they are small fish, they are abundant, so when we find some of them, we know there are more, he said. Get a small beaver pond, and it can support thousands of chub. They are a food source for trout and salmon, but are over-predated by nonnative fish like bass.
NFI biologists are planning to seek out and collaborate with partners in the Molalla basin in 2014 and beyond to sample additional areas. In addition, NFI will seek out public and private landowners who are willing to allow introductions of Oregon chub into suitable habitat, to increase the number of populations and add resiliency for the species.
The places where we find chub are also refuge habitat for salmon and trout in winter, productive habitat, Bangs said. So if the community continues supporting these kinds of habitat, you will see more trout and salmon. They are a natural part of the river itself. When people are supporting chub, they are supporting trout and salmon.