Influence of Life-History Parameters on Persistent Organic Pollutant Concentrations in Blubber of Eastern North Pacific Gray Whales (Eschrichtius robustus)

Exposure to persistent organic pollutants (POPs) can significantly impact marine mammal health, reproduction, and fitness. This study addresses a significant 20-year gap in gray whale contaminant monitoring through analysis of POPs in 120 blubber biopsies. The scope of this substantial sample set is noteworthy in its range and diversity with collection between 2003 and 2017 along North America's west coast and across diverse sex, age, and reproductive parameters, including paired mothers and calves. Mean blubber concentrations of polychlorinated biphenyls ( n-ary sumation PCBs), dichlorodiphenyltrichloroethanes ( n-ary sumation DDTs), and chlordanes ( n-ary sumation CHLs) generally decreased since previous reports (1968-1999). This is the first report of polybrominated diphenyl ethers (PBDEs) and select hexachlorocyclohexanes (HCHs) in this species. Statistical modeling of the 19 most frequently detected compounds in this dataset revealed sex-, age-, and reproductive status-related patterns, predominantly attributed to maternal offloading. Mean POP concentrations differed significantly by sex in adults (17 compounds, up to 3-fold higher in males) but not in immatures (all 19 compounds). Mean POP concentrations were significantly greater in adults versus immatures in both males (17 compounds, up to 12-fold) and females (13 compounds, up to 3 -fold). POP concentrations were detected with compound-specific patterns in nursing calves, confirming maternal offloading for the first time in this species.

Automated summary

Exposure to persistent organic pollutants (POPs) can have significant effects on the health, reproduction, and fitness of marine mammals. This study fills a 20-year gap in gray whale contaminant monitoring by analyzing POPs in 120 blubber biopsies. The findings show that the concentrations of POPs differ based on sex, age, and reproductive status, primarily due to maternal offloading. The mean concentrations of POPs have generally decreased since previous reports, and the presence of polybrominated diphenyl ethers (PBDEs) and select hexachlorocyclohexanes (HCHs) in this species is reported for the first time.