The harp seal, Pagophilus groenlandicus, and the hooded seal, Cystophora cristata, are two Arctic species living in what is considered today as “the major sink of global mercury inputs”. In order to study mercury kinetics during lactation and fasting and assess the maternal transfer to offspring, tissues from 28 hooded seals and 36 harp seals (mothers and pups) were analysed for total mercury (T-Hg) content. Samples were freeze-dried, homogenised and analysed by atomic absorption spectroscopy. Tissue distribution in adults was similar for both species; Hg accumulated primarily in the liver and in kidneys. T-Hg concentrations showed that hooded seals are more contaminated than harp seals and are at risk of T-Hg mediated health effects. The physiological status of mothers (body condition and lactation) did not have an influence on their Hg burden, whereas the diet, the habitat use and the geographical distribution did. T-Hg burden of mothers was reflected in their pups. Newborns show similar concentrations as their mothers in most tissues. Gestation was identified as the major way of maternal transfer, while the ingestion of milk was found negligible. The more intense fasting strategy of hooded seals determined a stronger remobilisation of T-Hg during post-weaning fast.
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