Northwest Fisheries Science Center

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Document Type: Journal Article
Center: NWFSC
Document ID: 4217
Title: Toxicity of Forest Fire Retardant Chemicals to Stream-type Chinook Salmon Undergoing Parr-Smolt Transformation
Author: J. P. Dietrich, Mark S. Myers, S. A. Strickland, A. L. Van Gaest, M. R. Arkoosh
Publication Year: 2013
Journal: Environmental Toxicology and Chemistry
Volume: 32
Issue: 1
Pages: 326-347
DOI: 10.1002/etc.2052
Keywords: salmon,wildfire,toxicity,PHOS-CHEK,smolting

 Long-term fire retardants are used to prevent the spread of wildland fires. These products are

normally applied by aircraft and are specifically intended for terrestrial application, but fire

retardants have entered aquatic habitats and resulted in fish kills. We examined the toxicity of

two fire retardant products; PHOS-CHEK 259F and LC-95A, on salmon undergoing parr-smolt

transformation. Yearling stream-type Chinook salmon at smolt stage were exposed to eight

concentrations of each retardant and a no-exposure control for 96 hours to determine acute

toxicity. Concentrations of the products that caused 50% mortality (LC50) were 140.5 and 339.8

mg/l for 259F and LC-95A, respectively. Gill tissues were identified with histopathological

lesions and conditions attributable to fire retardant exposure. Un-ionized ammonia may have

been sufficient to cause acute mortality during 259F exposure, but additional factor(s)

contributed to mortality during LC-95A exposure. In addition, saltwater and disease challenges

were performed to determine the impacts of non-lethal product exposures on fish health. The

PHOS-CHEK exposure did not adversely affect juvenile Chinook salmon's disease susceptibility

to Listonella anguillarum. However, previous PHOS-CHEK exposure did significantly reduce

survival during saltwater challenge. Reduced salmon survival due to prior fire retardant

exposure during the innate transition from freshwater rearing environments to seawater may

negatively impact species recovery.

Theme: Recovery, Rebuilding and Sustainability of Marine and Anadromous Species
Foci: Describe the relationship among human activities and species stock status, recovery, rebuilding and sustainability.