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Science Panel Reviews Monitoring/Evaluation Plan For Walla Walla Spring Chinook Hatchery
Posted on Friday, November 02, 2018 (PST)

A panel of scientists completed their review of a monitoring and evaluation plan for the new Walla Walla spring chinook hatchery on the south fork of the Walla Walla River that will produce a half million yearling spring chinook each year.


In addition to the juvenile releases, adult hatchery origin fish will be outplanted into the Touchet River and into Mill Creek.


The Confederated Tribes of the Umatilla Indian Reservation first submitted the M&E plan in 2015 and on June 15, 2015 the Northwest Power and Conservation Council asked the Independent Scientific Review Panel to do a Step 1 review of the Tribe’s the plan. That was completed and the ISRP has just completed its Step 2 review Oct. 29, 2018 (


In an August 17 cover letter to the Council, Gary James, fisheries program manager at the CTUIA, said the M&E plan “is a critical component of the Walla Walla Spring Chinook Hatchery Program.” He said the plan’s purpose is to:


-- Evaluate hatchery performance relative to goals and expectations;

-- Identify the key metrics that will be monitored;

-- Describe how metrics will be monitored (field and in-hatchery methods and analytical approaches); and

-- Explain how this information will be used to manage harvest, escapement, trap operation, and hatchery actions.


The August 17 plan also describes the scientific framework that was used to determine quantitative goals for the program and it includes an adaptive management process that, it says, will allow managers to adjust the program to ensure that both harvest and conservation goals are met.


“M&E results will be used to document the extent that conservation and harvest goals are being achieved over the anticipated time frames,” James said in the letter.


The Council recommended an expansion at the Walla Walla Hatchery at its October 2013 meeting. The project aims to rebuild the spring chinook salmon population in the river through hatchery supplementation.


The ISRP said the latest M&E Plan is an improvement over the 2015 Plan and that it adequately addresses most of the ISRP’s recommendations from the Step 1 review. Overall, the ISRP said, this latest plan meets scientific review criteria, but with eight qualifications:


1. Evaluate the possibility of overcompensation (density dependence) during the spawner to smolt life stage. The ISRP said the tribe proposes to allow up to 1,100 hatchery and natural origin chinook salmon to spawn in the Walla Walla River during Phases 1 and 2, but that that spawner density exceeds the current capacity of the watershed to support the salmon. Although the tribe acknowledges the limited capacity of the watershed, it says the high spawner abundance might encourage the salmon to disperse throughout the watershed and so reduce density and potentially increase overall production of juveniles. This is an idea that may work provided monitoring and evaluation are adequate to detect overcompensation, if it should occur, the ISRP said.


2. Additional detail about hatchery operations is needed to clarify how: (a) broodstock will be held, (b) spawning will occur, (c) survival and growth metrics will be determined for the incubation and rearing periods, and (d) how and where smolts will be released. In particular, the ISRP urges the proponents to give a high priority to assessing and monitoring precocious maturation (i.e., minijack production via the 11-ketotestostorne assay).


3. Provide more details about the existing hatchery program, including annual and brood-year-specific data on the number of hatchery fish released, their survival rates and the number of adults returning since 2000.


“The proponents seem optimistic that “releasing twice as many hatchery fish than were released from 2002 to 2015 will achieve the total return goal for Phase 1 (a 3-year geomean of 1000 adults). However, the annual hatchery returns to Nursery Bridge Dam … and the total returns … (3-year geomean range 11-698) do not seem high enough to justify this optimism.”


4. Explain why SARs measured at McNary Dam for natural origin spring chinook from the Yakima River have been used, despite expectations that overall SARs would be lower for natural origin smolts from the Walla Walla River due to additional mortality during migration upstream of McNary Dam.


5. Provide more detail about the pHOS and PNI (proportionate natural Influence statistic) values expected in each phase and the extent to which pHOS values could be controlled. pHOS is the percent of hatchery fish spawning in the wild. PNI is a genetic risk management tool.


6. Evaluate in-river mortality of smolts between the location of hatchery release and the location of the downriver traps.


7. Evaluate whether Oct. 1 is early enough to begin smolt enumeration at the rotary screw trap. There is an indication that large numbers of smolts were captured in the first sampling period (16-31 October), which suggests that many smolts might have emigrated prior to that time. Undercounting smolts would bias many metrics.


8. Consider additional data to verify assumptions used to calculate several key metrics, including: a) SAR values might be underestimated by not accounting for project fish that are harvested in the Columbia mainstem; b) Detection probabilities for carcasses in the South Fork Walla Walla River should be measured each year to ensure that pHOS and PNI values are reliable;. c) Predictions from the PCDRISK model about potential risks that project fish pose to other native species should be considered as hypotheses that require testing with additional field work.


Also see:


-- CBB, October 11, 2013, “Council Recommends Hatchery Expansion For Reintroducing Salmon To Walla Walla River,”

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