Skip to main content
U.S. flag

An official website of the United States government

Western Fisheries Science News, May 2017 | Issue 5.5

Exploring the Role of Non-Native American Shad in the Columbia River Basin

Adult American shad collected from the lower Columbia River. Photo by USGS.

American shad—an anadromous fish endemic to the Eastern seaboard— were first introduced to the West Coast in 1871, when the U.S. Fish Commission introduced the species from the Hudson River in New York to the Sacramento River in California.  American shad were intentionally stocked in many other areas in the West for forage, food, sport, and commercial fishing. Since then, the species has expanded its range along the coast as far north as Alaska. Today, the largest existing population of American shad is in the Columbia River. Estimates of 1-6 million adults are counted per year at Bonneville Dam, the lower-most dam on the Columbia River. With the presence of so many shad in the Columbia River, people are wondering how these populations are affecting other fish species, including many ESA-listed salmon stocks, and the overall ecosystem. The role of American shad within the aquatic community is poorly understood and many questions have arisen related to their introduction, including potential competition with juvenile salmon and their role in food webs.

USGS scientist Craig Haskell, a Pathways Program participant and recent Ph.D. graduate from Washington State University, has been addressing some of these questions and giving us further insight into the role of American shad in the Columbia River. Haskell’s graduate research focused primarily on the interactions between nonnative American shad and fall Chinook salmon in Lower Columbia River food webs, requiring extensive field and laboratory efforts. Research findings are now being published and shared.

In an article in Ecology of Freshwater Fish, Haskell looks at shifting marine-derived nutrients in salmon and shad. Like Pacific salmon, nonnative American shad have the potential to convey large quantities of nutrients between the Pacific Ocean and freshwater spawning areas in the Columbia River Basin. Although American shad are now the most numerous anadromous fish in the Columbia River Basin, the magnitude of the resulting nutrient flux owing to the shift from salmon to shad is unknown. This paper quantifies the nutrient flux attributable to nonnative American shad and infers how nutrient loading may have shifted spatially and temporally from what was historically contributed by salmon.

Another publication in Transactions of the American Fisheries Society evaluates competition for food between juvenile salmon and nonindigenous shad in the Columbia River Basin. In the lower Columbia River, juvenile Chinook salmon overlap with juvenile American shad during July and August. American shad juveniles are abundant and have the potential to reduce growth of young salmon through competition for food such as Daphnia. Daphnia—small planktonic crustaceans— are also important prey for salmon in the lower Columbia River, but it is unknown whether salmon diet overlaps with shad, and if so, whether diet overlap results in reduced fitness (for example, reduced growth) of salmon. Haskell and co-authors studied the diet and consumption of subyearling Chinook salmon and juvenile American shad during periods of anticipated species overlap. Results show that shad can reduce zooplankton availability for salmon. However, smaller juvenile shad also become prey for salmon after Daphnia abundance declines in late July and August. This prey switch from Daphnia to juvenile shad, which have a higher energy density, helps juvenile salmon compensate for the higher metabolic costs of migrating through reservoirs in summer when water temperature is high.

Haskell plans to publish additional findings on juvenile salmon’s consumption (functional) response to changes in prey density-findings that can be used to evaluate competition between salmon and shad. Lastly, Haskell and his co-authors examine the growth repercussions of juvenile salmon’s prey shift from plankton to juvenile shad and of the high water temperatures associated with migrating during summer.

Newsletter Author - Rachel Reagan



USGS Scientist to Provide Technical Assistance to Lao People’s Democratic Republic Government Developing Fish Passage Guidelines: John Beeman, Scientist Emeritus with the WFRC, met with Lao People’s Democratic Republic (Lao PDR) government officials to assist with their first ever fish passage guideline document. Mr. Beeman and Dr. Zhiqun Daniel Deng of the Pacific Northwest National Laboratory met with Lao PDR officials in Vientiane, Laos in early June 2017 to discuss their recent report “Methods for assessing fish passage at dams on large mainstream rivers: implications for the Mekong River.” The new guidelines are part of an effort to prepare for completion of up to 10 mainstream dams on the Mekong River in Lao PDR. The report and meeting were part of an ongoing project of Interior’s International Technical Assistance Program.

USGS Scientist Gave Presentation at California Congressional Hearing: On May 24, 2017, Research Fish Biologist Russell Perry provided a presentation to the Joint Committee on Fisheries and Aquaculture - Salmon Hearing at the State Capital in Sacramento, CA. The hearing provided legislators and their staff an opportunity to learn more about California’s salmon fisheries. Perry gave a presentation on survival of juvenile Chinook salmon migrating through the Sacramento-San Joaquin River Delta. He discussed the Delta, studies that have been done to better understand juvenile salmon movements, and possible factors affecting juvenile salmon survival.

USGS Scientists Share Research on the White Salmon, WA: On May 24, 2017, WFRC scientists Jill Hardiman and Ian Jezorek, in conjunction with Mid-Columbia River Fisheries Enhancement Group’s director, Margaret Neuman, hosted a field site visit at the White Salmon River juvenile fish trap to share on-going research in the White Salmon River, WA. The participants, included members from the WA State Salmon Recovery Funding Board Monitoring Panel, Clark-Skamania Fly Fishers, Yakima Nation Fisheries, Friends of the White Salmon, Wet Planet rafting company, Klickitat County, and U.S. Fish and Wildlife Service. Michelle Scott of the Enterprise, a newspaper in White Salmon, joined the group. The intent of the field visit was to discuss efforts by USGS and other entities to evaluate the extent of natural salmonid recolonization since removal of Condit Dam.

USGS Presents at Independent Science Advisory Board Meeting: On May 12, 2017, WFRC scientists gave a presentation titled “Building a Life-Cycle Model for Naturally Produced Fall Chinook Salmon in the Snake River Basin” to the Columbia River Basin Independent Science Advisory Board (ISAB). The presentation was part of a Life-cycle Model Review involving USGS scientists Russell Perry, John Plumb, and Ken Tiffan, and described the goals, type of model being built, incorporating life stages, model structure, preliminary results and next steps. The ISAB serves the National Marine Fisheries Service (NOAA Fisheries), Columbia River Indian Tribes, and Northwest Power and Conservation Council by providing independent scientific advice and recommendations regarding scientific issues that relate to the respective agencies’ fish and wildlife programs.


WFRC Employee Recognized in USGS Honor Awards Ceremony: On May 9, 2017, Joe Warren of the WFRC attended the USGS Honor Awards Ceremony at the National Center in Reston, VA. Warren accepted an award in the safety category for his contributions in cleaning and organizing for a safer work environment at the WFRC’s Columbia River Research Laboratory.


USGS Scientists Contribute to New Book on Fish Diseases: USGS scientists at the WFRC contributed chapters to a new book on important fish viral and bacterial diseases. The book, "Fish Viruses and Bacteria: Pathobiology and Protection" (edited by P.T.K. Woo and R.C. Cipriano) includes 25 illustrated chapters describing prevalence, distribution, economic impact, transmission, physiopathology, clinical signs, diagnosis, and current preventive and control strategies for each disease discussed. This book is intended as a concise reference for fish health professionals, fishery managers and students. Diane Elliott authored a chapter on Renibacterium salmoninarum, the causative agent of salmonid bacterial kidney disease, and Gael Kurath co-authored a chapter on infectious hematopoietic necrosis virus (IHNV) of salmonid fishes.

Elliott, D.G. Renibacterium salmoninarum. Pages 286-297 in Woo P.T.K. and R.C. Cipriano (eds.). Fish Viruses and Bacteria: Pathobiology and Protection. Wallingford, England. DOI: 10.1079/9781780647784.0000

Leong, J-A. C. and G. Kurath. 2017. Infectious haematopoietic necrosis virus. Pages 13-25 in Woo P.T.K. and R.C. Cipriano (eds.). Fish Viruses and Bacteria: Pathobiology and Protection. Wallingford, England. DOI: 10.1079/9781780647784.0000