Can ice breeding seals adapt to habitat loss in a time of climate change?

Climate change associated declines in sea ice will have seriousimpact on species that rely on ice for reproduction and/or feeding. Little is known about the impacts on ice-dependent, sub-Arctic species or on how these species may adapt, although the ecosystem changes are likely to be most rapid along the ice edge. Harp seals (Pagophilus groenlandicus) require stable ice for pupping, nursing and the first weeks after weaning when the young develop the capacity to swim and feed. Although ice conditions in the Northwest Atlantic have varied over the past 40 years, in 2010 and 2011, the total extent of ice suitable for whelping harp seals was at, or near, the lowest ever recorded. These years of exceptionally poor ice provided us with an opportunity to improve our understanding about how ice breeding seals may respond to the conditions expected in the future. Harp seals responded to poor ice conditions differently, depending on the presence or absence of ice at the beginning of the pupping period. If no ice was present, females moved away from their traditional whelping areas to find suitable ice. If small amounts of ice were present, females gave birth even if the ice was too thin to sustain the pups, resulting in high pup mortality. There was no evidence to indicate that harp seals pupped on land even in areas where ice was absent. Young seals that drifted to shore had high levels of abandonment and mortality. If the predicted warming trends continue, ice-breeding harp seals will encounter more years with poor ice conditions and may eventually adapt by moving north. Until then, they will continue to have increased levels of mortality that could result in the disappearance of the most southern breeding component in the Gulf of St Lawrence.