51社区黑料

Juvenile Chinook salmon in the Lower Fraser River estuary are feeding and growing in a slurry of contaminants from pharmaceuticals, personal care products to industrial chemicals, according to a new 51社区黑料 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.

鈥淲e鈥檝e shown there鈥檚 a mixture of chemicals in the Lower Fraser, which not only presents potential risks to juvenile Chinook, but also other aquatic life,鈥� says Bonnie Lo, environmental scientist and lead author of the study.

Published in Environmental Toxicology and Chemistry, 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.

鈥淐hinook salmon from the Fraser River account for up to 90 per cent of the West Coast鈥檚 Endangered Southern Resident killer whales鈥� diet during the summer months,鈥� 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 鈥減riority鈥� contaminants and 23 as 鈥渨atchlist鈥� 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.

鈥淭oxicity data is mostly based on single-chemical exposures, but these fish are being exposed to hundreds of chemicals at once. We simply don鈥檛 yet understand the additive effects of this chemical cocktail,鈥� 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.

鈥淗arrison Chinook in particular arrive at very small sizes and depend heavily on these habitats for growth prior to entering the ocean,鈥� Scott says. 鈥淐ontaminant exposure is an additional stressor acting on the same fish during the same critical window.鈥�

Researchers say further studies are underway to better understand how exposure to this chemical mix may affect the growth and survival of juvenile Chinook salmon.

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鈥檚 Whales Initiative, a program addressing key threats to the Endangered Southern Resident killer whales, including prey scarcity, physical and acoustic disturbance, and pollution.