Arctic marine mammal population status, sea ice habitat loss, and conservation recommendations for the 21st century

Abstract

Arctic marine mammals (AMMs) are icons of climate change, largely because of their close association with sea ice. However, neither a circumpolar assessment of AMM status nor a standardized metric of sea ice habitat change is available. We summarized available data on abundance and trend for each AMM species and recognized subpopulation. We also examined species diversity, the extent of human use, and temporal trends in sea ice habitat for 12 regions of the Arctic by calculating the dates of spring sea ice retreat and fall sea ice advance from satellite data (1979–2013). Estimates of AMM abundance varied greatly in quality, and few studies were long enough for trend analysis. Of the AMM subpopulations, 78% (61 of 78) are legally harvested for subsistence purposes. Changes in sea ice phenology have been profound. In all regions except the Bering Sea, the duration of the summer (i.e., reduced ice) period increased by 5–10 weeks and by >20 weeks in the Barents Sea between 1979 and 2013. In light of generally poor data, the importance of human use, and forecasted environmental changes in the 21st century, we recommend the following for effective AMM conservation: maintain and improve comanagement by local, federal, and international partners; recognize spatial and temporal variability in AMM subpopulation response to climate change; implement monitoring programs with clear goals; mitigate cumulative impacts of increased human activity; and recognize the limits of current protected species legislation.

Range contraction and increasing isolation of a polar bear subpopulation in an era of sea‐ice loss

“…More detailed genetic analyses would be worthwhile to explore this further. Sea‐ice loss is predicted to continue and information from telemetry and marked or recovered bears through long‐term monitoring programs (i.e., Laidre et al., 2015) will be critical to understanding increased fragmentation among polar bear subpopulations.…”

Advection in polar and sub-polar environments: Impacts on high latitude marine ecosystems

“…Many species of polar seabirds and marine mammals require sea-ice habitat for foraging, resting, and raising young (e.g., Moore and Huntington, 2008;Kovacs et al, 2011;Santora, 2014;Laidre et al, 2015;Delord et al, 2016). Ice floes provide refuge for seabirds and seals from their predators, such as killer whales and leopard seals (e.g., Visser et al, 2008;Durban, 2010, 2012).…”

“…These changes in the physical system are impacting the biological components of polar oceans (e.g., Clarke et al, 2007;Van Dijken, 2011, 2015;Constable et al, 2014;Gutt et al, 2015). Future decreases in sea-ice cover will have severe impacts on organisms dependent on the sea-ice habitat for some or all of their life activities (Smith et al, 2014a;Laidre et al, 2015). In the ocean many organisms depend on passive transport for dispersal.…”

“…For example, in years of extreme sea-ice cover in East Antarctica, seabird reproduction largely failed (Emmerson and Southwell, 2008;Barbraud et al, 2015). Many species of marine mammals in both the Arctic and the Antarctic require sea ice as a platform on which to rest, forage, give birth to and nurse their pups, as well as to escape from predators (e.g., Laidre et al, 2015). As the area of ice available to them declines, they will be forced to use alternative habitats or decline.…”

“…Polar bears use ice for migration, mating, and to prey on seals. With reductions in sea ice, the sea-ice habitat will shrink substantially and the numbers of both polar bears and ice-dependent seals are expected to decline (Loeng et al, 2005;Durner et al, 2009;Rode et al, 2014;Laidre et al, 2015). Polar bears may have to retreat to land, which will likely lead to increased starvation for lack of appropriate food and declines in abundance (Hamilton et al, 2014).…”