This paper presents new census data and population estimates for penguins, blue-eyed shags, and southern giant petrels from 26 sites in the Antarctic Peninsula, collected by the Antarctic Site Inventory from 1994 to 2000. For nine sites, population data or estimates are published for the first time. The newly discovered gentoo penguin population of 215 nests at Herofna Island (63°24'S, 54°36'W) represents the easternmost location where this species has been found breeding in the Peninsula. All three pygoscelid penguins — gentoo, Adelie, and chinstrap — were found breeding at Gourdin Island (63° 12'S, 57° 18'W), the fourth known site where these species nest contiguously in the Peninsula. During the period, significant declines in nesting populations of blue-eyed shag were documented at three northwestern Peninsula locations.

The results are presented of the first winter ice navigation demonstration, using synthetic aperture radar (SAR) images from the Canadian satellite RADARSAT, onboard the nuclear icebreaker Sovetskiy Soyuz in the Kara Sea region in April–May 1998. While ERS SAR data only could cover part of the sea ice in this large area, the demonstration showed that RADARSAT ScanSAR images with 100 m pixel size could be used to map all relevant ice areas with a few 500 × 500 km scenes. SAR images transferred onboard icebreakers in near real time offer an excellent possibility to select optimal sailing routes in difficult ice conditions such as those that were encountered by this expedition. SAR images were also used for planning of operations prior to the expedition. This study compares sub-satellite sea-ice observations with RADARSAT SAR as well as Okean side-looking radar (SLR) signatures of the major ice types and features found in the Kara Sea during winter. Wide-swath SAR images will become available from several new satellites in the near future, such as Envisat, scheduled in 2001, and RADARSAT-2, in 2002. Satellite SAR images will therefore play an increasingly important role in operational ice monitoring both in the Northern Sea Route and in other ice areas.

The subject of retreating global sea-ice extent is a matter of grave concern, and any new method that promises reliable information about past ice-extent parameters must be welcomed. However, the method proposed by De la Mare should be viewed with caution for four reasons. First, his predictions of sea-ice extent do not correspond with known observations of sea-ice extent from research published in 1936 and 1972. Second, his predictions correlate much more closely with the whale-sighting data recorded by Hansen (1936). Third, since Hansen's sea-ice extent data do not correspond closely with his whalesighting data, it must be questioned whether whale-based data should be used for retrospective predictions relating to sea-ice extent. And finally, information from the IWC indicates that De la Mare's datasets are not considered accurate. Predicting sea-ice edge extent is complex, and, it would seem, a purely biological approach is not necessarily the most accurate method to adopt.