By Dr. Becker
A collaboration between scientists and native communities in Alaska and Canada has shed new light on the lives of beluga whales (also known as white whales). Two populations of the whales in the Pacific Arctic were tagged and tracked from 1997 to 2012 to gauge depths and patterns of beluga diving.
In addition, information from native communities added insights into the whales' migrational behavior. Barbara Mahoney of the National Oceanic and Atmospheric Administration (NOAA) Fisheries department in Alaska explained in The Christian Science Monitor:1
"What we've heard from the Alaskan hunters is that you'll find belugas where there's food … Belugas will spend the summer in one area, where there's food, but then they'll follow the freezing of the sea to overwinter further south."
How Deep Do Beluga Whales Dive?
Among the information relayed by the tagged belugas (using satellite-linked time-depth recorders) was new information about the maximum depth of daily dives, which was nearly 3,000 feet.
However, most often the whales dove to depths of 650 feet to 1,000 feet, which is the area where Arctic cod, one of belugas' favorite foods, were most abundant. The researchers noted:2
"These results are consistent with a hypothesis that Arctic cod are a primary prey item for Pacific Arctic belugas and suggest that foraging belugas dive to depths that maximize prey encounters."
Other data revealed by the study related to how long the belugas stay underwater. This varied among regions and different beluga populations.
At least two groups — Eastern Chukchi Sea and Beaufort Sea belugas — would regularly dive for 6-hour periods, which suggests they were "diving to the seafloor in shallow shelf regions."
Life in the Arctic Ocean
Beluga whales are uniquely suited for life in the Arctic Ocean (some also live in subarctic waters).
They have a five-inch layer of blubber that "jiggles … kind of like really dense Jell-O," according to the featured study's lead author Donna Hauser, a doctoral student in the University of Washington's School of Aquatic and Fishery Sciences.3
They also have milky white skin (perfect for blending in among sea ice) and a tough dorsal ridge (kind of like knuckles along their backbone) in lieu of a dorsal fin. The dorsal ridge helps belugas to navigate sea ice.
When their local waters freeze, many Arctic belugas migrate to the south; those trapped by the ice may die or become prey to polar bears (belugas are also targeted by killer whales and indigenous hunters).4 However, some beluga whales do not migrate but rather stay year-round in one location.
As for diet, beluga whales are opportunistic feeders, meaning they'll eat whatever foods they can find. Favorites include fish, crustaceans and worms.
Unlike other whales, beluga whales have cervical vertebrae that are not fused. This means they're able to move their heads up, down and side-to-side — an adaptation that likely helps them find and catch prey in ice-covered areas.5 Belugas are related to narwhals (sometimes known as "unicorn" whales).
Belugas live in social groups called pods that may range in size from two or three whales to several hundred. They communicate using clicks, whistles and other noises.
They can even mimic other sounds and also use sound to help find prey.6 Echolocation is also important to belugas. According to the NOAA's Alaska Regional Office:7
"Belugas use echolocation, a biological sonar, to maneuver in murky water, find prey, find breathing holes (in ice), and avoid predators. They also use sound to communicate by producing a variety of clicks, chirps, and whistles."
Human Activities May Threaten Beluga Whales
There is one population of beluga whales near Anchorage, Alaska that's threatened — the Cook Inlet belugas. Once numbering at 1,300, the population had dwindled down to 284 in 2011.
It's not known why this unique population of belugas, which have been separated by geographic barrier from other beluga populations for 10,000 years, are declining. However, their close proximity to one of Alaska's fastest-growing and most heavily populated regions may be playing a role.8
Beluga whale populations as a whole are relatively stable. They are, however, negatively impacted by human activities, including:9
✓ Increased development
✓ Shipping industry
✓ Oil and gas production and transport
✓ Commercial fishing
✓ Habitat destruction
✓ Noise pollution
As researchers learn more about the habits of these impressive whales, they'll be able to identify their needs and establish protections for the animals in the rapidly transforming Arctic ecosystem where they reside.