Receding Glaciers Causing Seals to Wander

Although the captivating species of the harbor seals are fairly stable in many parts of the world and can be seen in just about every zoo, when it comes to southeastern Alaska, there is a decline. The harbor seals rest and breed at nearby glacier icebergs; however, since the availability of the ice is changing, it affects the seals’ behaviors, which are important for their reproduction and survival.

There are two different studies that have been conducted, one through the Alaska Department of Fish and Game (ADFG) and the other through the National Park Service (NPS). Both found the seals could be changing their behavior and distribution in order to acclimate with the changing locations of ice because of the glaciers retreating.

Jamie Womble, who is leading the Glacier Bay NPS research, is working closely with her team to figure out the precise movements and distribution of the seals and how it relates to the glacier ice.

One particular method being used that is working effectively is Aerial tracking. This involves flying above the ice and counting the seals. Another method for tracking the seals movements is through the use of GPS tracking devices, which are glued to the seals. There is little risk to the seals since during the following summer’s molt season, the GPS tracking technology will come off safely.

Although the seals movements and migration have been going extensively away from Glacier Bay, Womble and her team found the seals’ return rate was fairly high following breeding/pupping season.

Womble and her team studied both the patterns of seal movements and distances in which they traveled in relation to the ice. Ice distribution inside John Hopkins Inlet was also studied by the team. This analysis was then correlated with aerial tracking information so that they team could examine the relationship between the seals and the ice.

Seal pupping is decreasing due to the eastern side Glacier Bay rapid retreat. During the time when the pups are newborn and are being weaned off of the mother seals, the pups rest on the flat icebergs. It was found, however, that there were no longer any seals pupping in Muir Inlet by 2008 and in McBride Inlet, there were only 200 seals counted.

The importance of studying how, why and when the seals use the glaciers and whether the retreat of them is having a negative impact on the seals is being emphasized in an ADFG report. Also being documented in the report are other glacier retreat instances, seals movements, weight, diet, and how tour vessels affect the seals.

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