AGE AND SIZE TRENDS AND MALE-FEMALE DIFFERENCES OF PCBs AND DDE IN DALLI-TYPE DALLu27S PORPOISES, PHOCOENOIDES DALLI OF NORTHWESTERN NORTH PACIFIC (Ninth Symposium on Polar Biology)

摘要

Adult and immature male and female, one newborn pup and a fetus of Dalli-type Ballu27s porpoises (Phocoenoides dalli) collected from northwestern North Pacific were analyzed for the PCB and DDE levels in their blubber. A wide difference existed in the levels of these chemicals between males and females. Concentrations of both the chemicals increased consistently with age in the bodies of males. On the other hand, there was a decrease with age in the levels of these compounds in females after about two years of age, possibly due to a lactational and parturitional transfer of these compounds. When comparing the concentrations of these compounds in the adult males and females of various marine mammals, the females had always less than 50% of the levels to those found in the respective males. These percentages were found to linearly decrease with increase in lactational period of the species indicating a prominent excretion via milk to calf rather than via placenta to fetus. By using the organochlorine data it seems to be possible that PCBs and DDE can be used as chemical tracers in determining some parturitional and lactational characteristics in marine mammals.