Rivers of Resilience – Yakima

In Science Friday, Steelhead Files, Washington by Nick Chambers

It can be hard to maintain faith in the steelhead world.  As noted in the recent article by Bill Herzog, it seems like we are losing wild summer runs faster than we can recover them. I would hedge that many, if not most, anglers feel the same.


Steelhead are not disappearing for lack of effort though. Frankly, it’s amazing to think of the sheer financial investment made on behalf of salmon and steelhead recovery.  Billions — yes billions — of dollars have been spent to restore habitat and improve populations of salmon and steelhead, many of which are severely depleted and listed for Federal protection under the Endangered Species Act.



Although the massive investment has not resulted in the formal recovery and delisting of any steelhead populations, the efforts have not been in vain. There are places where wild steelhead populations have improved after habitat restoration and elimination of hatchery fish. There are populations that have displayed remarkable resilience.


Unfortunately, those examples can be difficult to find and they do not get the attention they deserve.


It’s not surprising, then, that some anglers question whether it is possible for wild steelhead to rebuild in the absence of hatcheries. To be fair, we agree that not all wild populations are equally capable of rebuilding and that hatcheries are necessary for opportunity in such places. But, that does not mean hatcheries should be used everywhere.




In fact, there are persuasive reasons to limit the use of hatcheries and identify wild populations that have the highest potential for recovery. For that reason, we believe it is essential to educate anglers about the potential for wild summer steelhead to rebuild.


We selected three populations that illustrate the resilience of wild steelhead, including the Yakima River, Wind River, and Asotin Creek. Why these populations? Largely because they are the only populations that we could find where hatchery plants were stopped and there was good pre and post hatchery monitoring to determine the annual population size of wild steelhead.


While hatchery fish have been excluded from sections of other rivers (e.g., N.F. Clackamas), wild fish do interact with hatchery fish outside of where they are excluded and the releases of hatchery smolts within those basins have varying ecological effects on emigrating wild smolts, such as competing for food and habitat. Even the rivers we selected still deal with stray hatchery adults and hatchery smolts on their way to the ocean. Nonetheless, they remain some of the only examples that have adequate data for looking at population trends in wild steelhead over long periods of time.


We will highlight one population per week over the next three weeks. Each description will include a review of the population size of wild steelhead before and after the hatchery closure, a brief discussion of the main factors thought to influence the wild population, and implications for recovery.


Yakima River

Perhaps there is no better example of wild steelhead resilience than in the Yakima River, a large drainage (6,150 square miles!) in the middle Columbia River. The region is generally semi-arid, though the headwaters are at much higher elevation than the mouth, so environments at either end of the drainage are very different. Land use is also variable, but recovery actions have focused strongly on removing barriers and restoring stream flow that had been depleted due to agricultural operations.


It is a diverse watershed, and in addition to steelhead, supports a robust population of wild rainbow trout and Chinook and coho salmon. Scientists estimate the drainage historically supported between 21,000-100,000 wild steelhead, but as we see in the graph, the population of wild steelhead declined to less than 700 fish in the early-1990s.  The river had a long history of hatchery steelhead releases, but those were stopped in 1993.


In looking at Figure 1, we see that a low level of wild steelhead abundance persisted until the early-2000s and reached a peak of almost 5,900 fish in 2010. The offspring of the last hatchery plants in 1993 returned as adults in 1994-1995, which means 1996 was first year of adult returns that did not have any hatchery influence from smolts or adults. The average run size during the post-hatchery period was 2,659 fish compared to 1,304 during the years when hatchery steelhead were being released — more than twice as many fish.


The rebound is likely due to several factors. Ocean survival improved in the early 2000s, and there have been alterations to dams and spill practices that improved juvenile outmigration survival. Also, federal and state agencies, the Yakama Nation, and other stakeholders – including Trout Unlimited – collaborated on an array of restoration projects that improved habitat and increased stream flows.  Last,the Yakama Nation implemented a kelt reconditioning program to improve the survival and frequency of repeat spawning steelhead, and the data suggests the program has been responsible for a 7 to 10 percent increase in the abundance of adult wild steelhead.


While difficult to parse out the relative effects of each factor (other than the kelt contributions) – including hatchery effects – without more in-depth data and analyses, the take home message is that wild steelhead rebounded in a stream located above four major dams in the Columbia River. Certainly the importance of habitat restoration and improved smolt survival cannot be underscored enough. They are the foundation for the resurgence.


Has the resurgence in the Yakima been matched in other nearby watersheds, such as the Wenatchee, that has a hatchery? It depends on how you look at the data. For example, both populations have generally trended upward since the early-2000s due to improved smolt survival and habitat restoration.


However, the Yakima wild summer steelhead population has averaged 4,620 fish over the most recent five years for which data was available (2010-2014) compared to 1,585 fish per year in the Wenatchee over the same time period. We might not expect the Wenatchee to produce as many steelhead because its basin size is only about 25 percent of the Yakima, but then again, there are substantial portions of the Yakima that are not used by spawning or rearing steelhead relative to how much of the Wenatchee is used.  Further, the extent of rebound in the Yakima has been greater.  The average run of 4,620 summer steelhead from 2010-2014 represents more than a ten-fold increase over its smallest run size of 398 fish in 1996, while the average of 1,585 fish in the Wenatchee represents only a five-fold increase over its smallest run of 242 fish in 1997.

Despite the rebound the Yakima has remained closed to steelheading since 1994 when the population was in the midst of a trough in abundance. Nonetheless, the surge in abundance illustrates that wild steelhead can rebound dramatically in a relatively short period of time, and while the Wenatchee has a hatchery, it has rarely been open to angling since it was first listed under the ESA in 1997.


In summary, the Yakima summer steelhead population is a bright spot for recovery in the interior Columbia and indicates that wild fish, given adequate habitat, can make it above multiple dams. That bodes well for the potential future of steelheading in the Yakima.



Figure 1. Annual abundance of adult wild steelhead in Yakima River when the hatchery steelhead were being released and after the hatchery releases were ceased.