Tissue toxicants and prespawn mortality in Willamette River Chinook salmon

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Tissue toxicants and prespawn mortality in Willamette River Chinook salmon Matthew L. Keefer & George P. Naughton & Tami S. Clabough & Matthew J. Knoff & Timothy J. Blubaugh & Mark R. Morasch & Peter G. Green & Christopher C. Caudill

Received: 6 August 2019 / Accepted: 23 December 2019 / Published online: 4 January 2020 # Springer Nature B.V. 2020

Abstract In some Pacific salmon Oncorhynchus spp. populations, many adults die after reaching freshwater spawning sites but prior to spawning, a phenomenon known as prespawn mortality (PSM). Causal factors for PSM are often uncertain, but pathogens, warm water temperature, and environmental toxicants have been implicated in several studies. In this two-year project, we examined the relationship between toxicants and PSM in a threatened population of spring-run Chinook salmon O. tshawytscha (Walbaum) in the Willamette River, Oregon. Muscle and skin samples from 63 female carcasses were screened for ~125 potential toxicants, including trace elements, pesticides, and organohalogens. Mean concentrations for five toxicants selected for their known adverse effects on M. L. Keefer (*) : G. P. Naughton : T. S. Clabough : M. J. Knoff : T. J. Blubaugh : M. R. Morasch : C. C. Caudill Department of Fish and Wildlife Sciences, College of Natural Resource, University of Idaho, 875 Perimeter Drive, MS-1136, Moscow, ID 83844-1136, USA e-mail: [email protected] M. J. Knoff Knoff Telemetry LLC, 3500 27th PI W, F225, Seattle, WA 98199, USA

Present Address: M. R. Morasch Environmental Assessment Services, 350 Hills St. Suite 112, Richland, WA 99354, USA Present Address: P. G. Green Department of Civil and Environmental Engineering, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA

salmonids were: 4.3 (SD = 2.0) ng/g cadmium, 72.9 (122.7) ng/g nickel, 10.0 (9.0) ng/g lead, 12.7 (8.6) ng/g polychlorinated biphenyls (PCBs), and 17.6 (10.3) ng/g DDT (an organochlorine pesticide). Using generalized linear models, we found no statistical differences in toxicants concentrations between successful (n = 37, 58.7%) and unsuccessful (n = 26, 41.3%) female spawners. We conclude that selected contaminants did not provoke acute toxicity in Willamette River Chinook salmon. It remains unknown whether sub-lethal or chronic toxicant effects on adult salmon physiology or behavior have affected the fitness of this threatened population. Keywords Organohalogens . Pesticides . Pollutants . Prespawn mortality . Trace elements . Toxic chemicals

Introduction A vast array of chemical pollutants accumulate in aquatic ecosystems and can negatively impact the behavior, survival, and fitness of fishes (Scott and Sloman 2004; Islam and Tanaka 2004; Bosch et al. 2016; Hamilton et al. 2017). Important classes of persistent xenobiotics that affect fishes include trace metals (e.g., cadmium, copper, lead, mercury), organochlorine and organophosphate pesticides (e.g., diazinon, DDT), pharmaceuticals, industrial chemicals (e.g., flame retardants, polychlorinated biphenyls [PCBs]), petroleum byproduct