Flesh residue concentrations of organochlorine pesticides in farmed and wild salmon from British Columbia, Canada

• Published in: Environmental Toxicology and Chemistry
• Main Authors: Kelly, Barry C., Ikonomou, Michael G., Higgs, David A., Oakes, Janice, Dubetz, Cory
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2011
• Subjects: British Columbia; Canada; Sockeye; Atlantic salmon; Pink salmon
• Online Access: http://dx.doi.org/10.1002/etc.662; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fetc.662; https://setac.onlinelibrary.wiley.com/doi/pdf/10.1002/etc.662

Abstract The present study reports measured levels of organochlorine pesticides (OCPs) in commercial salmon feed ( n = 8) and farmed Atlantic, coho, and chinook salmon ( n = 110), as well as wild coho, chinook, chum, sockeye, and pink salmon ( n = 91). Flesh residue concentrations (ng/g wet weight) of dichlorodiphenyltrichloroethanes (DDTs), hexachlorocyclohexanes (HCHs), chlordanes, chlorobenzenes (CBz) and cyclodiene pesticides (e.g., dieldrin, mirex) were 2 to 11 times higher ( p < 0.05) in farmed salmon compared with wild salmon. Concentrations were positively correlated with flesh lipid levels. Farmed Atlantic salmon (12–15% lipid) typically exhibited the greatest OCP burdens compared with other salmon species. However, when expressed on a lipid weight basis, concentrations of OCPs (ng/g lipid weight) in wild salmon, in many cases, exceeded those levels in farmed salmon. Observed interspecies and site‐specific variations of OCP concentrations in farmed and wild salmon may be attributed to divergent life history, prey/feed characteristics and composition, bioenergetics, or ambient environmental concentrations. Calculated biomagnification factors (BMF = C F / C D , lipid wt) of OCPs in farmed salmon typically ranged between two and five. Biomagnification of chemicals such as DDTs, chlordanes, and mirex was anticipated, because those compounds tend to exhibit high dietary uptake and slow depuration rates in fish because of relatively high octanol–water partition coefficients ( K OW s > 10 5 ). Surprisingly, less hydrophobic pesticides such as hexachlorocyclohexanes and endosulfans ( K OW s < 10 5 ) consistently exhibited a high degree of biomagnification in farmed salmon species (BMFs > 5). This is contrary to previous laboratory and field observations demonstrating fish BMFs less than 1 for low K OW chemicals, because of efficient respiratory elimination of those compounds via gills. The results suggest that ambient seawater concentrations and bioconcentration‐driven accumulation may play a key ...