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The boat ramp at Thief Valley Reservoir currently leads to a reservoir mostly void of water. Due to irrigation needs, Oregon Department of Fish and Wildlife District Biologist Tim Bailey estimates the reservoir ends up being drained about three to four times per decade. (PHIL BULLOCK/The Observer)
Anglers concerned about future of Thief Valley Reservoir
With the recent drainage of Thief Valley Reservoir resulting in significant fish die-off for the second year in a row, three fishermen from the Pilot Rock area had a sit-down with Oregon Department of Fish and Wildlife District Biologist Tim Bailey Monday to discuss fish stocking policies and procedures for the reservoir.
John Taylor, Doug Holcomb and Gene Brill have all been fishing at Thief Valley for many years and were concerned with the fish die-off in consecutive years.
Bailey said that historically Thief Valley Reservoir, which is 16 miles south of Union, was stocked with 100,000 three-inch fingerlings each spring. In 2007, Bailey decided to change that policy and stock 32,000 fingerlings in May and 30,000 sub-yearling rainbow trout in early November, a process that has been carried out each year since.
“We did creel surveys in 2008, 2009 and a statistical creel survey in 2010,” Bailey said. “And what that told us was that those fall-release fish contribute to the fisherman’s creel at twice the rate as the spring fingerlings. In other words, they survive better.”
Some years there is a surplus of fish which can be added to the count. In 2012, 40,000 additional trout were stocked in November.
By stocking fish in the fall when the reservoir starts filling with water again following the irrigation season, it ensures a fishing season the following year.
“If you lose all of your fingerlings in May and the reservoir gets drained — like 2013 for example — and we have no other fish allocated to the reservoir, there’s no fishery the following year,” Bailey said. “Even if there’s water all year long there, there’s no fish to be caught.”
Bailey also added that when the reservoir does get drained, something he estimates happens three to four times per decade, it kills off predators and competitors to trout.
“There’s an advantage basically of re-setting that fishery,” Bailey said. “If you didn’t start from scratch with only trout in the lake, your productivity of your trout is going to decline because you have all those competitor fish there.”
There is also the economic boost the fishery has.
Bailey said that it used to cost around $3,000 to stock Thief Valley with 100,000 fish in the spring. Stocking sub-yearling trout, which are close to six inches, costs a little more, but Bailey estimated that it costs somewhere between $5,000 to $10,000 to stock the reservoir the way he does it now.
Compare that to the 3,000 angler visits the reservoir gets per year at an average cost of $45 into the economy per visit — including gas, food, tackle — and Bailey said the value is too good not to have the fishery.
“To me it’s kind of a no-brainer,” Bailey said. “If you have a good water year, where you can maintain a fishery seven out of 10 years, economically it’s justified.”
The fish that get stocked at Thief Valley are raised in Irrigon, but Bailey said the fingerlings traditionally do well in the reservoir. He said that fingerlings stocked in May can grow as large as 14 inches by the following May during a good water year.
“That’s our preferred management method at all these reservoirs is to use fingerlings,” Bailey said. “They’re cheap to produce, and if you have a place like Thief Valley, they grow. And the product is much more highly preferred by the angler.”
Bailey, who is an avid fisherman himself, said he’s not happy when he sees dead fish line the shores when irrigation needs drain the reservoir by early September. But with irrigators having rights to the water, there isn’t much he can do about that.
“You can go from a good water year where you might have 30- to 40-percent survival rate of fingerlings to one where you have 5 (percent) and you never saw that because there’s water there,” Bailey said. “But when it goes dry, the public sees that and you get upset.”
Bailey said that the plan for this year is the same as last year, and he plans on stocking 30,000 sub-yearlings in early November. Depending on the rainfall in 2014, those fish could be as big as 14 inches next summer, when anglers flock to Thief Valley.