Reproductive transfer and variation of body load of organochlorine pollutants with age in fin whales (Balaenoptera physalus).

The body load of tDDT (p,p'DDT + o,p'DDT + p,p'DDE + p,p'TDE) and polychlorinated biphenyls (sum of congeners) was estimated for 169 fin whales to study age and sex-related variation and to calculate the quantity of these compounds transferred to offspring through reproduction. Blubber was the body compartment containing the greatest quantities of organochlorines, but its relative contribution to total load was lower than in other cetaceans because in fin whales muscle and bone are also significant lipid reserve sites. In male fin whales, organochlorine body loads increased with age but tended to reach a plateau in fully grown individuals. In adult females, loads decreased with age because of transfer to offspring cancelling the rise in loads associated with body growth; as a consequence, the amount of organochlorines transferred during a reproductive cycle also declined with age. This transfer is lower than that found for other cetaceans because fin whales have a shorter lactation period. According to the calculations, the first offspring of a female fin whale receives about 1 g of PCB and about 1.5 g of tDDT. These amounts will progressively decrease in subsequent reproductive cycles to reach a minimum of 0.2 g PCB and 0.3 g tDDT in an old female. Therefore, the first calf delivered is the one most likely to be affected by pollutants.