Development and validation of protocols to differentiate PCB patterns between farmed and wild salmon

Area of Science:

• Environmental Chemistry
• Ecotoxicology
• Marine Biology

Background:

• Polychlorinated biphenyls (PCBs) are persistent organic pollutants found in aquatic ecosystems.
• Understanding PCB congener patterns in salmon is crucial due to their ecological and dietary significance.
• Farmed and wild salmon may exhibit different PCB profiles based on their feeding regimes and environments.

Purpose of the Study:

• To compare Polychlorinated biphenyl (PCB) congener patterns in farmed and wild salmon species from British Columbia.
• To investigate the influence of species, trophic level, feeding preferences, and diet on PCB composition.
• To develop a better framework for understanding PCB distribution in salmon and marine food chains.

Main Methods:

• Full congener Polychlorinated biphenyl (PCB) analyses were performed on salmon samples.
• Principal Component Analysis (PCA) and linear decomposition using Aroclor 1242, 1254, and 1260 were employed.
• A novel classification protocol for PCB congeners based on structure-activity groups, chlorine number, and hydrogen presence was developed.

Main Results:

• Farmed salmon showed Polychlorinated biphenyl (PCB) patterns similar to their food sources.
• Wild salmon separated into two groups: chinook and coastal coho with higher chlorinated congeners (Aroclor 1260-type), and chum, pink, sockeye, and remote coho with lower chlorinated congeners (Aroclor 1242-type).
• Wild chinook salmon had the highest PCB concentrations and toxic equivalents (TEQs), with profiles dominated by higher chlorinated congeners.

Conclusions:

• Wild salmon Polychlorinated biphenyl (PCB) profiles are primarily determined by trophic level, feeding preferences, and longevity, with metabolism playing a minor role.
• Environmental delivery mechanisms, such as atmosphere versus runoff, can influence PCB profiles more than biotransformation.
• The new classification protocol enhances the understanding of Polychlorinated biphenyl (PCB) distributions in salmon and marine food webs.