Distribution and haul-out behavior of harbor seals in Glacier Bay, Alaska

Abstract

Over 5000 harbor seals haul out on icebergs calved from tidewater glaciers in Muir and Johns Hopkins inlets in Glacier Bay, Alaska. During June, these sites are used primarily by parous females and pups, and in August, by molting seals. The number of mothers and pups was higher than expected for the total number of seals in Glacier Bay, indicating an immigration of some parturient females from outside Glacier Bay. The number of seals counted varied throughout the day with greatest numbers around midday. In Muir Inlet the number of seals hauled out was positively correlated with percent ice cover. Ice that is suitable for hauling out may presently limit the abundance of seals in this area. The retreat of Muir Glacier has dramatically reduced the ice available to seals and, if it continues, will likely result in the elimination of drift-ice habitat in the near future. Seals from both inside and outside Glacier Bay apparently use ice habitat in Muir and Johns Hopkins inlets when giving birth, when nursing pups, and when moulting for protection from terrestrial and marine predators, and because it is relatively abundant and easily accessible at all tides and times.