Persistent Bioaccumulative and Toxic Contaminants (PBTs) in Pacific Herring (Clupea pallasii), and the Trophic Transfer of PBTs in Puget Sound's Pelagic Food Web

Pacific herring (Clupea pallasii) are exposed to toxic contaminants in Puget Sound, WA at levels that may affect their health and reproductive success.  We compare contaminant loads in Puget Sound herring stocks, and illustrate Puget Sound’s Central Basin as a hot spot of persistent bioaccumulative and toxic (PBT) chemicals in the northeastern Pacific region.   Herring and other small, schooling, pelagic planktivorous fishes also play a role in the trophic transfer of PBTs, resulting in exposure to their predators, including Pacific salmon, rockfishes, lingcod, piscivorous seabirds, and marine mammals. We use tissue residues of polychlorinated biphenyls (PCBs), delta 15-nitrogen, and fish age from multiple species including phytoplankton, krill (Euphausia pacifica), juvenile forms of Pacific hake (Merluccius productus) and walleye pollock (Theragra chalcogramma), and adult herring, hake, and pollock,  to model increasing accumulation of PBTs with increasing trophic level.  We compare these biomagnification models across four oceanographic basins in Puget Sound representing a wide range of contaminant loads to discuss basin-specific trophic pathways for PBTs in top predators.