Melting Arctic sea ice may up whale predation

Los Angeles: Melting sea ice may shift migration routes of Arctic whale, which in turn may lead to increased predation of the species, a new study has warned.

Researchers from Florida Atlantic University (FAU) in the US, evaluated the relationship between changing sea ice and the migration of the Arctic whale also known as white whale and beluga whales.

They also evaluated the summer residency patterns of a number of populations over two decades of dramatic sea ice changes in the Pacific Arctic.

Beluga whales (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 behaviour and ecology of this species,” said Greg O’Corry-Crowe, research professor at FAU.

Researchers used a combination of genetic profiling, sighting data and satellite microwave imagery of sea ice in the Bering, Chukchi and Beaufort seas for the study.

They found some dramatic shifts in migration behaviour 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.

For the study, researchers used genetic “fingerprinting” to investigate 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. Researchers analysed 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 behaviour with implications for population viability, ecosystem structure and the subsistence cultures that rely on them,” said O’Corry-Crowe. The study appears in the journal Royal Society Biology Letters.

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