Western Fisheries Science News, October 2017 | Issue 5.10

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As fall days grow shorter, scientists and field crews from WFRC’s Klamath Falls Field Station (KFFS) continue to conduct field work and tackle questions about Lost River suckers and shortnose suckers— fishes endemic to the Upper Klamath Basin of Oregon and California that are listed as endangered under the Endangered Species Act. Scientists are conducting their annual fall trammel net sampling for suckers in Clear Lake Reservoir, located in Modoc County, California. Clear Lake is considered an important water body in recovery planning for these fishes, as it contains the largest reproducing populations outside of Upper Klamath Lake in Oregon. Recovery continues to be a challenge for populations throughout the Klamath Basin, but findings in Clear Lake have been offering some glimmers of hope for these fish and their future.

Finding fish during sampling this year has been challenging, partly due to the volume of water in the lake from 2016-2017 winter inflows, making it harder to determine how populations are doing. But, these levels may help to continue recent recruitment success. Catches in Clear Lake last fall showed for a second year in a row that there was a pulse of new adult-sized shortnose suckers joining the population. That's some good news, given many years of poor recruitment in both Upper Klamath Lake and Clear Lake. Recent work by scientist Summer Burdick, looking at juvenile suckers in Clear Lake, also shows numerous age classes are present. It appears that new cohorts are formed in years when reservoir water levels and flows in tributaries are high enough to allow spawning migrations. Importantly, juvenile suckers are surviving beyond their first year of life.

Concerns with high mortality of suckers in the first year of life in Upper Klamath Lake have led to questions about fish health and condition. Scientists from KFFS are collaborating with fish health experts in WFRC’s Seattle lab to study the health and condition of juvenile suckers as it relates to the dynamics of water quality. In the recent past a study was done to compare the health and condition of juvenile suckers between Upper Klamath Lake and Clear Lake, but no strong evidence was found related to likely causes of the comparatively high mortality in Upper Klamath Lake. In a newly released USGS report scientists further examine juvenile suckers collected in Upper Klamath Lake in 2014-2015 to better understand the relationship between juvenile sucker health and water quality, which can be highly dynamic and at times extreme in that system.

Suckers may move between Clear Lake and its tributaries, and make more extensive use of the tributaries, than previously thought. For example, detections showed that a small PIT-tagged sucker (< 100 mm SL) travelled more than 35 stream kilometers from a site in Willow Creek near the Oregon-California border down to the lake in 2014. In addition, an adult tagged in Clear Lake sampling was caught in 2016 by partners at U.S. Fish and Wildlife Service during electrofishing sampling in a similar area to where the small sucker was tagged, indicating that lake fish may travel farther to spawn than previously thought. This has led to interest in surveying the spawning tributaries in summer 2018 to assess summertime distribution of suckers in the tributaries.

Recovery of endangered species can be challenging, especially in an altered and dynamic environment. By gaining a better understanding of the species needs, we will be able to better inform natural resource managers on recovery efforts.

Newsletter Author: Rachel Reagan

Events

USGS Scientist Presents Keynote Presentation at Finnish-Swedish Transboundary River Commission: USGS Scientist Jeff Duda gave the keynote presentation to the 2017 Water Parliament of the Finnish-Swedish Transboundary River Commission on October 25. He discussed dam removal, river restoration and salmon recovery on the Elwha River. He also gave a presentation on U.S. trends of dam removal and synthesis of dam removal studies based on work at the USGS Powell Center. Duda was interviewed for a newspaper article (in Finnish behind paywall) following a public presentation in Joensuu, and National Public Television, and National Public News online following the keynote presentation about the Elwha River dam removals at the 2017 Water Parliament in Tornio., Finland.

Publications

New Paper Links Functional Response and Bioengergetics to Estimate Juvenile Salmon Growth in a Reservoir: Freshwater food webs are important for juvenile salmon as they migrate seaward. In the Columbia River Basin, main-stem food webs have been drastically altered from river impoundment, the introduction of non-native species, and supplementation with hatchery conspecifics. The effects of these food web changes are mostly unstudied but are likely important for juvenile salmon growth and their ultimate survival. In a new paper in PLoS ONE, scientists from the WFRC and Washington State University examined the feeding behavior of juvenile Chinook salmon and its relation to growth by estimating the functional response of juvenile salmon to changes in the density of Daphnia, small aquatic crustaceans important in reservoir food webs. They also estimated salmon growth across a broad range of water temperatures and daily rations of two primary prey, Daphnia and juvenile American shad using a bioenergetics model. 

Haskell, C.A., D.A. Beauchamp, and S.M. Bollens. 2017. Linking functional response and bioenergetics to estimate juvenile salmon growth in a reservoir food web. PloS ONE 12(10): e0185933.

New Publication Evaluates Health and Condition of Endangered Juvenile Suckers in Upper Klamath Lake: Most mortality of endangered Lost River and shortnose suckers in Upper Klamath Lake, Oregon, occurs within the first year of life. However, juvenile suckers in nearby Clear Lake Reservoir, California, survive longer and may even recruit to the spawning populations. In a new report, scientists examine suckers collected in 2014-2015 to better understand the relationship between juvenile sucker health and water quality from Upper Klamath Lake, where water quality can be dynamic and, at times, extreme.

Burdick, S.M., C.M. Conway, D.G. Elliott, M.S. Hoy, A. Dolan-Caret, and C.O. Ostberg. 2017. Health and condition of endangered young-of-the-year Lost River and shortnose suckers relative to water quality in Upper Klamath Lake, Oregon, 2014–2015: U.S. Geological Survey Open-File Report 2017-1134, 40 p.