Occurrence, Distribution and Behaviour of Beluga (Delphinapterus leucas) and Bowhead (Balaena mysticetus) Whales at the Franklin Bay Ice Edge in June 2008

Ice edges and polynyas have long been noted for their high biological productivity within the Arctic environment. In June 2008, an aggregation of belugas and bowheads was identified at the Franklin Bay ice edge in the eastern Beaufort Sea, adjacent to the Cape Bathurst polynya. We conducted five ice-edge surveys by helicopter to study the distribution and behaviour of the whales. Bowheads were sighted in significantly shallower water than belugas. In addition, we used the helicopter platform to observe behaviour. Belugas and bowheads were engaged in directed travel and diving near and under the ice. Five beluga dives were timed and found to have an average duration of 106 +/- 61 s (+/- SD) and a range of 30-197 s. One bowhead under-ice dive was timed and had a duration of 417 s. The under-ice dives are consistent with feeding behaviour observed for belugas and bowheads in other ice-edge location. We hypothesize that higher prey densities along the Franklin Bay ice edge than in the adjacent open water may attract belugas and bowheads to the ice edge in June. Further research is needed to identify the abundance and type of prey species consumed and to assess the relative energetic importance of spring ice-edge feeding to the eastern Beaufort Sea beluga and bowhead populations.