1994 Arctic Ocean Section
tion on location and activity patterns. Unfortunately both satellite radio trans-
mitters failed within four months of attachment, possibly due to battery fail-
ure. Prior to the loss of radio contact, both bears moved off in a northeasterly
direction, staying in regions of 90% ice cover or greater.
Tissue samples from the bears handled were assayed for organochlorines.
The contaminant loads in the adipose tissue samples from the captured bears
have been determined by R.J. Norstrom (Environment Canada, Ottawa). The
sum of all polychlorinated biphenyls (PCBs) in the bears ranged from 1.7 to
6.6 g/g lipid, that of the pesticide chlordane from 0.8 to 2.7 g/g lipid, and
that of the pesticide DDT from 0.1 to 0.4 g/g lipid. These CHC contamin-
ant loads were in the lower range of values determined for polar bears from
most of the circumpolar, near-land populations. For all three measured contam-
inants, mean contaminant values in the adipose tissue fell within the lower
50% of mean values for the circumpolar populations of polar bears that have
been sampled previously.
As with bears, more ringed seals were seen than we expected--more than
150, usually singly or in groups of fewer than three. The sighting frequency of
seals remained relatively constant once we were past the continental shelf.
Seals were observed on all except eight days of the transect. On five of those
days, heavy fog limited visibility.
Our sampling protocol was not intended to estimate the population size for
polar bears or ringed seals. We found far more bears (12), tracks of bears (15)
and ringed seals (>150) along our line of transect than anticipated. Clearly
there is a food resource (seals) available to polar bears in the Arctic Basin, and
therefore there may be a resident population of bears. The failure of the satel-
lite tracking program did not allow us to monitor the movements of the two
adult females. The results of the DNA assays and stable-isotopic signatures
from the bears are not yet completed. It is hoped they will support or belie the
hypothesis that polar bears inhabiting the Arctic Ocean basin are indigenous.
Estimating the size of any population of marine mammals in the deep Arctic
Basin is a more difficult problem and will require a concerted effort by re-
searchers from many countries.
Michel Gosselin and other biological oceanographers collected data during
AOS-94 suggesting that a significant, if not major, portion of the food web
exploited by polar bears is associated with the epontic algae, gammarid am-
phipods and Arctic cod of the multi-year ice floes and not with the pelagic
food column. If corroborated, these findings will give considerable insight
into the ecology of marine mammals. The relative importance of ice algae and
amphipods compared with phytoplankton and copepods may influence the
bioaccumulation of CHCs in the higher trophic levels. Certainly the feeding
ecology of seals and polar bears in any region of the Arctic is poorly under-
stood. As vertebrate ecologists, we eagerly anticipate another opportunity to
study the marine mammals in such a remote and fascinating environment.