Flesh Quality of Market-Size Farmed and Wild British Columbia Salmon

Abstract

This study compared the flesh quality of farmed and wild sources of British Columbia (BC) salmon with respect to concentrations of polychlorinated biphenyl compounds, polychlorinated dibenzodioxins/dibenzofurans and their associated toxic equivalents, total mercury (THg), methylmercury (MeHg), and selected fatty acids of known importance for human health viz., omega-3 (n-3) highly unsaturated fatty acids (n-3 HUFAs) and (n-6) fatty acids. Skinned fillets from known sources of farmed Atlantic, coho, and chinook salmon (n = 110) and wild coho, chinook, chum, sockeye, and pink salmon (n = 91) were examined. Atlantic salmon contained higher PCB concentrations (means, 28-38 ng/g) than farmed coho or chinook salmon, and levels in these latter species were similar to those in wild counterparts (means, 2.8-13.7 ng/g). PCB levels in Atlantic salmon flesh were, nevertheless, 53-71-fold less than the level of concern for human consumption of fish, i.e., 2000 ng/g as established by Health Canada and the U.S. Food and Drug Administration (US-FDA). Similarly, THg and MeHg levels in all samples were well below the Health Canada guideline (0.5 microg/g) and the US-FDA action level (1.0 microg/g). On average, THg in farmed salmon (0.021 microg/g) was similar to or lower than wild salmon (0.013-0.077 microg/g). Atlantic salmon were a richer source (mean, 2.34 g/100 g fillet) of n-3 HUFAs than the other farmed and wild sources of salmon examined (means, 0.39-1.17 g/100 g). The present findings support the recommended weekly consumption guidelines for oily fish species (includes all BC salmon sources) for cardio-protective benefits as made by the American Heart Association and the UK Food Standards Agency.

Changing ratios of omega-6 to omega-3 fatty acids can differentially modulate polychlorinated biphenyl toxicity in endothelial cells

“…Whether the cardio-protective omega-3 fatty acids in fish neutralize or markedly decrease the potential health risks associated with exposure to persistent organic pollutants is not known. There appears to be some consensus that regular fish consumption should be encouraged for its overwhelming cardioprotective properties [38,39].…”

Tissue residue concentrations of organohalogens and trace elements in adult Pacific salmon returning to the Fraser River, British Columbia, Canada

“…No significant differences in metal tissue concentrations were apparent between the two salmon species studied. Previous studies have shown that chinook salmon tend to exhibit higher Hg concentrations compared with other Pacific salmon species, in part because of their comparatively high trophic position [23].…”

“…Analyses of organohalogens in salmon muscle and eggs samples were conducted at the Institute of Ocean Sciences (Sidney, BC, Canada). Procedures and quality assurance-quality control protocols employed for simultaneous extraction, cleanup, and quantification of multiple organohalogen contaminants (PCBs, PCDD/Fs, PBDEs, and OCPs) by gas chromatography-highresolution mass spectrometry (GC-HRMS) have been thoroughly detailed by Ikonomou and colleagues [22][23][24][25] 4 in a mortar, transferred quantitatively into an extraction column, and extracted with approximately 250 ml DCM/hexane (1:1 v/v). Thirty percent of the extract solution by weight was transferred into a 250-ml round-bottom flask.…”

“…For all analyses, the HRMS was operated at 10,000 resolution under positive EI conditions and data were acquired in the single ion resolving mode. The GC-HRMS conditions, the criteria used for congener identification and quantification, and the quality assurance-quality control procedures used for the quantification of PCDD/Fs and PCBs have been described in detail elsewhere [22,23].…”

“…Laboratory measurements of sample lipid content were determined for pooled composites during chemical analysis. Lipid contents of composite tissue samples were determined gravimetrically, after extraction of a 5-g subsample [22,23]. Lipid contents, expressed as a percentage of the original wet tissue weight, are summarized in Supplemental Data, Table S3.…”