How do Arctic sea ice changes affect whales?

Study tracks belugas in global warming era

 Adult beluga whales are migrating through fractured sea ice in the Alaskan Arctic.

Beluga whales migrating through fractured sea ice in the Alaskan Arctic. Photo by Vicki Beaver/NOAA.

Staff Report

The relationship between Arctic whales and sea ice is still largely a mystery, but there is increasing concern over how these species will adapt to climate related changes in sea ice. In a new study, researchers found the drastic sea ice changes under way in the Arctic could lead to more predation of beluga whales — and that could have “implications for population viability, ecosystem structure and the subsistence cultures that rely on them,” said Dr. Greg O’Corry-Crowe, a scientist with Florida Atlantic University.

The researchers  with FAU’s Harbor Branch Oceanographic Institute and a team of scientists working in collaboration with Native hunters in Alaska and Canada looked at genetic patterns to assess the relationship between changing sea ice and beluga whale migration, as well as summer residency patterns of a number of populations over two decades of dramatic sea ice changes in the Pacific Arctic.

The researchers found that, beluga whales, often known as the white whale, (Delphinapterus leucas) exhibited a tremendous ability to deal with widely varying sea ice conditions from one year to the next over a 20-year time frame in their return to traditional summering grounds each year.

“It was not clear how sea ice influences beluga whale migration patterns and their summer habitat use, and climate change has added urgency to determining how environmental factors might shape the behavior and ecology of this species,” said O’Corry-Crowe, whose research focuses on combining molecular genetic analysis with field ecology to study the molecular and behavioral ecology of marine apex predators.

Using a combination of genetic profiling, sighting data and satellite microwave imagery of sea ice in the Bering, Chukchi and Beaufort seas, O’Corry-Crowe and collaborators also found some dramatic shifts in migration behavior in years with unusually low spring sea ice concentration and in one case with an increase in killer whale (Orcinus orca) sightings and reported predation on beluga whales.

Genetic “fingerprinting” helped the team understand the population of origin of whales returning to four traditional coastal sites in the Alaskan and Canadian Arctic between 1988 and 2007. They compiled detailed beluga sightings and harvest data for the same period to assess inter-annual variation on timing of return.

They also analyzed sea ice data in the Bering, Chukchi and Beaufort seas to determine seasonal and regional patterns of sea ice from 1979 to 2014. They used data from tissue samples from 978 beluga whales, which were collected over a 30-year period.

“Continued reductions in sea ice may result in increased predation at key aggregation areas and shifts in beluga whale behavior with implications for population viability, ecosystem structure and the subsistence cultures that rely on them,” said O’Corry-Crowe.

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