A 10 400-Year-Old Bowhead Whale (<i>Balaena mysticetus</i>) Skull from Ellef Ringnes Island, Nunavut: Implications for Sea-Ice Conditions in High Arctic Canada at the End of the Last Glaciation

Аннотация

Variations in the distribution and radiocarbon ages of postglacial bowhead whale (Balaena mysticetus) remains throughout the Canadian Arctic Archipelago indicate that the range of this whale expanded and contracted several times during the Holocene. Since the annual bowhead migration reflects the preference of this species for an ice-edge habitat, fossil bowheads have been used to infer that significant variations in summer sea-ice extent occurred throughout the archipelago during the last 10.5 thousand years. Previous studies have demonstrated that climatic amelioration, concomitant with enhanced meltwater flux from the retreating Laurentide Ice Sheet, cleared sea ice from the inter-island channels of the central archipelago, enabling early Holocene bowhead whales to extend beyond the range of contemporary populations. A 10.4 ka BP bowhead whale skull was discovered on Ellef Ringnes Island in the northern Canadian Arctic Archipelago, 700 km north of its previously reported early Holocene range. Consequently, sea ice along the polar margin of the Canadian Arctic Archipelago is inferred to have been less extensive than previously recognized. Both biological evidence and glaciological evidence suggest that this reduction in sea-ice extent was the result of climate forcing, amplified by meltwater-driven outflows from the rapidly retreating marine-based sector of the Innuitian Ice Sheet. Following a reduction of these outflows at ~9 ka BP, sea-ice conditions worsened, despite ongoing climatic amelioration, preventing additional bowhead whale incursions until ~4 ka BP.