Northwest Fisheries Science Center

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Document Type: Journal Article
Center: NWFSC
Document ID: 7425
Title: Toxicity of Forest Fire Retardant Chemicals to Chinook Salmon with Different Life History Strategies and Their Potential to Recover Before Seawater Entry
Author: J. P. Dietrich, A. L. Van Gaest, S. A. Strickland, Greg P. Hutchinson, Alex B. Krupkin, M. R. Arkoosh
Publication Year: 2014
Journal: Science of the Total Environment
Keywords: salmon,toxicity,wildfire,fire retardant,PHOS-CHEK

 Long-term fire retardants are used to prevent the spread of wildland fire, but have inadvertently entered aquatic habitats and resulted in fish kills.  We examined the toxicity of two fire retardant products; PHOS-CHEK 259F and LC-95A, on Chinook salmon with two different life histories, ocean-type (OT) and stream-type (ST), at different stages of their development.  OT Chinook outmigrate to the ocean as subyearlings; whereas, ST salmon overwinter in freshwater and outmigrate as yearlings.  OT and ST salmon were exposed to the fire retardants prior to their parr-to-smolt transformation (presmolts) as subyearlings (ST and OT) and yearlings (ST only), as well as during their transformation (smolts) as subyearlings (OT only) and yearlings (ST only).  The salmon were exposed to eight concentrations of each retardant and a control for 96 hours to determine acute toxicity.  Lethal concentration values were determined by logistic regression for each life history and life stage exposed to the two fire retardants.  Among all life histories and life-stages tested, PHOS-CHEK 259F was most toxic to ST salmon at smolt stage and PHOS-CHEK LC-95A was most toxic to OT salmon at smolt stage.  To determine the impacts of sublethal product exposures on fish health as well as for the potential of recovery, 24-hour seawater challenges were performed immediately after fire retardant exposure, as well as after a recovery period.  Previous PHOS-CHEK exposure reduced survival during seawater challenge among salmon from both life histories undergoing parr-smolt transformation and was more pronounced after PHOS-CHEK LC-95A exposure.  However, this delayed effect was not observed 34 or more days after either PHOS-CHEK exposure.  We conclude that accidental PHOS-CHEK drops in salmon habitat that exposed fish immediately prior to seawater entry would have the most negative impact on Chinook salmon populations.


 Toxicity of fire retardants to salmon

Theme: Habitats to Support Sustainable Fisheries and Recovered Populations
Foci: Assess the impacts of toxic chemicals and other pollutants across biological scales, and identify pollution reduction strategies that improve habitat quality.
Characterize the interaction of human use and habitat distribution, quantity and quality.