Organochlorine Contaminants in Pinnipeds and Cetaceans from the North Pacific
Blubber samples from three cetacean and four species of pinnipeds, all from North Pacific waters, were analyzed to determine levels of PCBs and DDT. It is difficult to make comparisons between contaminant studies as techniques to analyze levels has improved over time and inter laboratory calibration have only been conducted in some labs. In this study, all samples were analyzed at the same laboratory. Opportunistic contaminant sampling of killer whales (Orcinus orca) in the Starichkov Island area near Eastern Kamchatka in the Russian waters of the North Pacific Ocean was completed on 13 animals during the summer season of 2002 and an additional six animals in the summer of 2003. Sum PCBs ranged from 12 to 3400 ng/g wet weight with a mean (± sd) load of 664 ± 237 ng/g wet weight (lipid adjusted mean equals 58143 ± 31603 ng/g). Mean (± sd) DDT levels were higher than PCBs with an average of 1005 ± 414 ng/g wet weight (lipid adjusted mean equals 105476 ± 68780 ng/g) and a range of 14 to 7200 ng/g wet weight. It is important to note that low lipid values in a sample tend to inflate the lipid adjusted numbers and therefore, wet weight may be a better inter-species comparison. In Beluga whales (Delphinapterus leucas), from the Cook Inlet region (n=8), sum PCBs ranged from 0.84 to 8.5 ng/g wet weight with a mean of 2.58 ± 0.91 ng/g wet weight (lipid adjusted mean equals 6546 ± 4159 ng/g). Mean DDT levels were 2.20 ± 1.13 ng/g wet weight (lipid adjusted mean equals 4054 ± 3286 ng/g) and a range of undetectable to 6.71 ng/g wet weight. In one Gray whale (Eschrichtius robustus) that stranded in the Turnagain arm of the Cook Inlet, sample sum PCBs were 200 ng/g wet weight (952 ng/g lipid weight) and sum DDTs were 98 ng/g wet weight (467 ng/g lipid weight). In adult Steller sea lions (Eumetopias jubatus), from the Bering Sea (n= 9), sum PCBs ranged from 990 to 5700 ng/g wet weight with a mean of 2410 ± 546 ng/g wet weight (lipid adjusted mean equals 5353 ± 1265 ng/g). Mean DDT levels were 2156 ± 479 ng/g wet weight (lipid adjusted mean equals 4802 ± 1059 ng/g) and a range of 587 to 4075 ng/g wet weight. For harbor seals (Phoca vitulina), (n=12), sum PCBs ranged from 150 to 3400 ng/g wet weight with an average of 920 ± 290 ng/g wet weight (lipid adjusted mean equals 1730 ± 582 ng/g). Mean DDT levels were 538 ± 104 ng/g wet weight (lipid adjusted mean equals 980 ± 194 ng/g) and a range of 56 to 1240 ng/g wet weight. In one Ringed seal (Phoca hispida) sample sum PCBs were 590 ng/g wet weight (868 ng/g lipid weight) and sum DDTs were 268 ng/g wet weight (394 ng/g lipid weight). Hawaiian monk seal samples analyzed in the same lab (Willcox et al 2004), had sum PCBs of 1200-3200 ng/g lipid weight and 230-1600 ng/g lipid weight of DDT concentrations. Levels were highest for Steller sea lions, which feed at the same or lower trophic level as other marine mammals investigated here and may suggest that Steller sea lions are either feeding in areas with higher concentrations of organochlorines or are not able to break down organochlorines as well as other marine mammals. Hawaiian monk seals from much lower latitudes than the other pinipeds, still had elevated concentrations of organochlorines. All of the pinnipeds and two of the three cetaceans had concentrations of PCBs above the EPA guidelines, confirming the global spread and persistence of these compounds.