Residues of PBDEs in northeastern Pacific marine fish: evidence for spatial and temporal trends

In the flesh (skinless fillet) of chinook, chum, coho, pink, and sockeye salmon (Oncorhynchus tshawytscha, O. keta, O. kisutch, O. gorbuscha, and O. nerka, respectively), sablefish (Anoplopoma fimbria) and walleye pollock (Theragra chalcogramma) from several sites in the northeast Pacific sampled between 2002 and 2008, tetra- and pentabrominated diphenyl ethers (BDEs) (BDE 47, 49, 99, and 100) dominated the congener distribution. Chinook and sablefish contained the highest concentrations, followed by sockeye, coho, and pink salmon, and pollock. In sockeye from the Bering Sea - Aleutians and from the Gulf of Alaska, total tri- to hepta-BDE concentrations fell significantly between 2002 and 2005; in sablefish from Gulf of Alaska, there was a steady but statistically nonsignificant decline in BDE concentrations between 2002 and 2008. Relative proportions of the main BDE congeners did not change appreciably over time, within species or location. All species except sockeye salmon showed a clear southeastward increase in BDE concentrations, implying an increasing gradient in general ecosystem contamination. In chinook, coho, and sablefish, especially, the southeastward trend in increasing total concentrations was associated with increasing proportions of BDEs 47 and 100. Chinook returning to western North American natal streams appeared to accumulate most of their PBDE burden towards the end of their migration. Fish from more northern sampling sites often had higher proportions of more highly brominated congeners than those from more southern sites, perhaps reflecting contamination from Asian sources where higher-brominated commercial PBDE formulations are used. In sablefish and pollock, the relative proportions of BDEs 99 and 47 varied inversely in almost a 1:1 ratio, implying debromination of BDE 99 to 47.