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Another Big Year For Willamette Coho Return; Last Hatchery Release Above Falls Was 1998
Posted on Friday, October 08, 2010 (PST)

With the 2010 coho salmon return the Willamette River basin on track to break existing records, Oregon fishery managers decided late last month to increase the bag limit for anglers.


The coho run headed for tributaries above Willamette Falls appears to be particularly strong. Through Sept. 30, a total of 15,019 adult coho had already passed the Oregon Department of Fish and Wildlife’s fish counting station at Willamette Falls in Oregon City. On average half of the year’s coho run will have passed the falls by the end of September.


That’s slightly higher than the 13,037 counted through Sept. 30 a year ago. By season’s end the 2009 coho count at Willamette Falls had established a record, 25,298. The previous high annual totals were 17,902 adults in 1970 and 17,410 in 1971. The facility began keeping fish count records in 1946.


Daily counts at the falls slowly increased though September. The largest counts to-date were 1,290 on Sept. 27, 1,214 on Sept. 28 and 1,017 on Sept. 30. The count on Sept. 29 was 869. There wasn’t a single daily count above 1,000 during last year’s record run.


In addition, strong returns have also been observed at ODFW’s Sandy Fish Hatchery and on Eagle Creek, a tributary of the Clackamas River. The Sandy and Clackamas rivers feed into the lower Willamette below the falls in the Portland metropolitan area.


Anglers can now keep an additional coho salmon on several Willamette Valley area streams under temporary fishing rules adopted by ODFW.


Effective Sept. 23, the daily bag limit for coho salmon increased to three fish on the Willamette, Clackamas, Sandy, Molalla, Santiam, Yamhill, South Yamhill and Tualatin rivers and Eagle and Gales creeks. Prior to the rule change, the limit was two coho per day.


“It’s exciting to see another strong return of coho this year,” said Todd Alsbury, fish biologist for ODFW’s North Willamette Watershed. “We’re always pleased when we are able to offer additional fishing opportunities to our constituents. This is especially true when many families are feeling the pinch of a tough economy.” 


On the Willamette River below Willamette Falls and on the Clackamas and Sandy rivers and Eagle Creek coho must be adipose fin-clipped in order to be retained. This requirement is intended to help protect unclipped wild fish that inhabit both of the Sandy and Clackamas. On the Willamette River and its tributaries above Willamette Falls, both clipped and unclipped coho may be retained.


Anglers are reminded that combined daily limits still apply when catching more than one species of anadromous fish. Accordingly, in those areas that are also open to retention of chinook salmon and steelhead, the combined daily bag limit is two adult fish, with the exception that one additional fish may be kept if it is an adipose fin-clipped coho (or any coho above Willamette Falls) or adipose fin-clipped steelhead.


Anglers should consult the 2010 Oregon Sport Fishing Regulations for more information on regulations, open areas, seasons and bag limits on these species.


Fishery officials estimate that most of the coho passing Willamette Falls were produced by natural spawning in the wild, though some may be strays from hatchery programs in Oregon's Clackamas River basin and elsewhere.


Coho are not believed to be native to the Willamette River basin above the falls. Their run timing brings them to the basin in late summer and early fall when river flows are at a low point. That makes the steep Willamette Falls a tough hurdle.


Winter steelhead and spring chinook salmon are native to the upper Willamette but they arrive in spring and early summer when the Columbia flows are high and push up the Willamette water level. The Willamette flows into the Columbia at Portland.


Coho were long ago introduced to the upper Willamette by the ODFW to provide fishing opportunity. But there was little success in producing high returns.


It was decided to phase out the hatchery coho program due to concerns of the lack of success at boosting fishing opportunity and their potential competition for habitat with chinook and steelhead stocks that had been listed under the Endangered Species Act.


The last time ODFW released hatchery-reared coho in the upper Willamette basin was in 1998. The high returns in the early 1970s were generated from massive releases of hatchery coho fry and presmolts nearing 10 million annually.


The coho are predominately fish produced by natural spawning in the wild in tributary rivers like the Tualatin, Molalla, Pudding and Yamhill. The Santiam River, which empties into the Willamette south of Salem, Ore., is the mostly southerly occurrence of coho in the drainage. The Willamette flows into the Columbia at Portland.


The coho have been found in the Willamette basin as far south as the north and south forks to the Santiam River, the Luckiamute River and Rickreall Creek, which all empty into the Willamette in the vicinity of Salem.


Last year biologists tracked radio-tagged fish to learn more about their behavior, and where they go to spawn. The largest number of fish went up the Yamhill and Tualatin, according to Tom Murtagh of the ODFW, but not before idling for awhile at the mouth of their natal stream.


“They would sit for 20-30 days, some of them,” Murtagh said. That should be a good thing for anglers. But unfortunately the coho, which are genetically similar to “early run” coho native to southwest Washington, don’t bite well in the freshwater environment.


“We’re not seeing a high harvest on them,” Murtagh said. They do seem to occasionally fall off their diet and “go on the bite for an hour or so” If the timing’s right, catching a full coho limit might be possible.


“They’re beautiful – silver, strong beefy looking fish,” he said. Most range from 8 to 13 pounds, though some weigh as much as 14 or 15 pounds.


Surveys of the tributary streams where the coho are known to have spawned showed “good densities of juvenile fish” this summer, Murtagh said. Ocean conditions appear to be favorable. And an entrenched “La Nina” tips the odds towards wetter winters in the Northwest, which would result in favorable migration conditions when the young coho from that strong 2009 spawning class head for the Pacific.


“Were expecting good numbers of fish to be heading out” next spring.


Though the coho seem to be finding their own spawning and rearing niche, officials are still wary of the non-native coho population growing to the point they might crowd the listed chinook and steelhead.


“There could be competition effects between these naturally produced coho and chinook and winter steelhead,” according to Murtagh, who said he would like to see more research undertaken to evaluate the interaction.


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