Study: Young Fraser River Chinook salmon swimming in chemical soup

Juvenile Chinook salmon in the Lower Fraser River estuary are feeding and growing in a slurry of contaminants, from pharmaceuticals to personal care products and industrial chemicals, according to a new Simon Fraser University study.

Researchers found more than 200 contaminants in water and fish tissue samples collected from five sites in the Lower Fraser River estuary, including common blood pressure and diabetes medications, antidepressants, caffeine and cocaine.

“We’ve shown there’s a mixture of chemicals in the Lower Fraser, which not only presents potential risks to juvenile Chinook, but also other aquatic life,” says Bonnie Lo, environmental scientist and lead author of the study.

Key findings 

• Water samples were taken from five sites in the Lower Fraser River estuary 
• Tissue samples were taken from juvenile Chinook from the Harrison stock  
• Samples were analyzed for more than 595 contaminants from up to nine chemical classes 
• Contaminants included flame retardants, pesticides, industrial chemicals, and pharmaceuticals (prescription drugs, cocaine, caffeine) 
• 288 organic contaminants were detected in water samples 
• 368 organic contaminants were detected juvenile Chinook tissue 
• 16 contaminants exceeded thresholds for aquatic life with potential for adverse effects  
• 23 contaminants worthy of secondary monitoring were detected  

Published in Environment Toxicology and Chemistry, the risk-based screening study focused on juvenile Harrison River Chinook, the largest Chinook stock in the Lower Fraser River. 

The findings are concerning for other marine animals that rely on Chinook salmon. 

“Chinook salmon from the Fraser River account for up to 90 per cent of the West Coast’s Endangered Southern Resident killer whales’ diet during the summer months,” says Tanya Brown, marine ecotoxicologist and senior study author. 

Decades of population declines mean more than 85 per cent of Chinook populations are now classified as Endangered or Threatened by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC).

Brown says that of the 595 contaminants measured, 16 were identified as “priority” contaminants and 23 as “watchlist” contaminants.

Priority contaminants are those with the potential for adverse effects to Chinook salmon as well as other aquatic life. These included pharmaceuticals and personal care products, pesticides, polycyclic aromatic hydrocarbons, flame retardants, and polychlorinated biphenyls (PCBs).  

The Canadian government has regulated many of the persistent and toxic chemicals that bioaccumulate in food webs. Watchlist contaminants are those that may pose risks and warrant future monitoring. 

“Toxicity data is mostly based on single-chemical exposures, but these fish are being exposed to hundreds of chemicals at once. We simply don’t yet understand the additive effects of this chemical cocktail,” says Brown.  

Juvenile Chinook in the Fraser River estuary are already contending with multiple stressors, including rising water temperatures and pathogen exposure, says Dave Scott, a salmon biologist at Raincoast Conservation Foundation and study co-author. 

“Harrison Chinook in particular arrive at very small sizes and depend heavily on these habitats for growth prior to entering the ocean,” Scott says. “Contaminant exposure is an additional stressor acting on the same fish during the same critical window.” 

Researchers say further studies are underway to better understand how exposure to this chemical mix may affect juvenile Chinooks’ growth and survival.

This collaborative research by SFU, Fisheries and Oceans Canada (DFO), Environment and Climate Change Canada (ECCC), and Raincoast Conservation Foundation, was funded by the Government of Canada’s Whales Initiative, a program addressing key threats to the Endangered Southern Resident killer whales, including prey scarcity, physical and acoustic disturbance, and pollution. 

Abstract

Many populations of anadromous Chinook salmon (Oncorhynchus tshawytscha) in the Fraser River in British Columbia, Canada, have experienced decades of decline, with 85% (14/16) of assessed populations classified as ‘Endangered’ or ‘Threatened’. During outmigration, these juvenile Chinook stocks transit through areas impacted by heavy agricultural use and urban and industrial development in the Fraser River watershed. The lack of biologically relevant assessments of environmental contamination in salmon habitats underscores a notable gap in conservation initiatives. Here, we screened organic contaminants measured in juvenile Chinook tissue and their habitat (i.e.,, water) to identify compounds that pose a potential risk to Fraser River Chinook populations. Over 595 organic contaminants (spanning eight contaminant classes) were measured in samples from five sites in the Lower Fraser basin. One hundred and thirty out of 288 (45%) of detected contaminants in water and 82 out of 368 (22%) detected in juvenile Chinook tissue were assessed against threshold values. These thresholds included published environmental quality guidelines (EQGs) and a variety of screening benchmark values, which were derived from in vivo, in vitro, or predictive modelling data across multiple databases. Sixteen contaminants were identified as “Priority” contaminants with the potential for adverse effects, and 23 were classified as “Watchlist” contaminants worthy of secondary monitoring. These included pharmaceuticals and personal care products, pesticides, polycyclic aromatic hydrocarbons, flame retardants and polychlorinated biphenyls. This preliminary risk-based screening of organic contaminants in the Lower Fraser River serves to inform monitoring and recovery efforts for culturally-valued Chinook populations, as well as the Endangered Southern Resident killer whales that depend on them.