Emerging contaminants in juvenile Chinook salmon: Patterns of exposure and implications for conservation

Efforts to recover populations of threatened Chinook salmon in the Pacific Northwest may be hindered by exposure to contaminants in the juvenile life stage. Here we leverage a large dataset collected by the Washington Department of Fish and Wildlife’s Toxic Biological Observation System to test for accumulation of 219 contaminants of emerging concern (CECs) in juvenile Chinook salmon and identify chemicals that could be affecting salmon physiology, behavior, or fitness at current exposure concentrations. We also highlight results obtained from the region’s two most urbanized watersheds, the Green/Duwamish and Puyallup/White, to demonstrate how these data can inform decision making to protect juvenile salmonids. We found that juvenile Chinook salmon sampled in the Puyallup/White watersheds had the highest average concentrations of CECs, and that six chemicals appeared to be ubiquitous and were found in all five river systems spanning a gradient of urbanization. In the subsequent detailed..., All data compiled for this manuscript were collected by the Washington Department of Fish and Wildlife (WDFW) between 2013 and 2023 and include 141 composite samples comprising 772 individual subyearling Chinook salmon collected between April and June during the peak of their seaward migration. Fish were captured using beach seines, lampara seines, and an in-river screw trap, with additional collections made directly from hatchery ponds at the Soos Creek Hatchery in Auburn, WA. All collections were conducted under an ESA Section 4(d) permit obtained by WDFW for the collection of listed Chinook salmon. Hatchery-origin fish were identified using fin clips, otolith thermal marks, and coded wire tags; all others were presumed to be of natural origin and are hereafter referred to as wild fish.
All chemical analyses were completed by the commercial laboratory SGS AXYS Analytical Laboratory (Sydney, B.C.). Multiple established extraction and analytical methods were used to test for a range of ..., , # Emerging contaminants in juvenile Chinook salmon: Patterns of exposure and implications for conservation

Dataset DOI: [10.5061/dryad.pc866t212](10.5061/dryad.pc866t212)

## Description of the data and file structure

Data compiled for this manuscript were collected by the Washington Department of Fish and Wildlife (WDFW) between 2013 and 2023 and include 141 composite samples comprising 772 individual subyearling Chinook salmon collected between April and June during the peak of their seaward migration.

### Files and variables

#### File 1: WDFW_JuvenileChinook_CEC_Data.xlsx

**Description:** Chemistry and sample datafile associated with manuscript ENVPOL-D-25-03840: \"Emerging contaminants in juvenile Chinook salmon: patterns of exposure and implications for conservation.\" Authors: Molly Shuman-Goodier, James Meador, Andrea Carey, Sandra O’Neill 

#### File 2: Table_S2_-_Analytes_and_Metadata.xlsx

**Description:** Table S2 accompanying manuscript ENVPOL-D-25-03840. The table contai...,