Beluga Whale Watching

Beluga Whale Watching

While polar bears usually dominate the media, Churchill is also home to the world’s largest and healthiest population of belugas on the planet. Last July, we featured an information piece about just what a Beluga is and what they do to pass the time.

The Beluga Whale (Delphinapterus leucas), also known as the white whale, is the most numerous of the three species of arctic whales. A relative of the narwhal’s, it has a circumpolar distribution, with a worldwide population estimated at 50 000-70 000 individuals.

Each summer, as the ice breaks up, these whales travel up major northern rivers to the warmer, shallow waters to feed, breed, and molt. The western Hudson Bay population is estimated at ~20 000 whales. Churchill is one of the most accessible places to see them, and hundreds of people from around the world come here in July and August to see and hear some of the 3 000 whales summering in the Churchill River estuary.

Characteristics
Belugas are small whales, measuring 3-5m long and weighing 300-500kg. Females are slightly smaller than males and lack shoulders, giving them a more streamlined appearance. Cows and calves generally travel together, as do groups of males.

The beluga has a relatively small head with an enlarged rounded forehead called the ‘melon’, which is used to focus or direct sound. Like the narwhal, the seven vertebrae in the neck of the beluga are not fused, allowing for considerable head mobility. They are toothed whales, with nine pairs of teeth in their upper jaw and eight in the lower. They have flexible lips, which give them their characteristic smiley face.

Belugas have no dorsal fin, allowing for better clearance under the sea ice. They do, however, possess a long dorsal ridge, used to break through several centimeters of ice to create breathing holes.

Blubber makes up to 40% of the beluga’s body weight, and may be up to 10 cm thick under the skin. It functions as an insulator in the chilly arctic waters, as well as an energy reserve.

Breathing
Beluga whales are marine mammals, breathing by means of lungs. The blowhole is a crosswise slit in front of the neck crease through which they inhale and exhale. They can dive down to 600m or more, and may remain under water for 25-30 minutes. This is possible as their muscles, blood, heart, and lungs are well adapted at using and storing oxygen efficiently.

Habits
Belugas travel in pods, congregating by the hundreds and even thousands in the summer to warm shallow waters, to moult, and feed, and mate and give birth. In the winter the formation of the sea ice (less breathing space) forces them into deeper and more open waters.

They are piscivorous, feeding on fish such as arctic cod and char, crustaceans, and mollusks. Judging from the numbers of capelin in the Churchill River, it is safe to assume these are a major food source for the local beluga population.

Sea canaries
Belugas are some of the most vocal creatures in the sea. Early whalers hearing belugas through the hulls of their ships termed them ‘sea canaries’. Sounds produced by the whales vary from high-pitched whistles and squeals, to ticking and clucking, and chirps.

Beluga sounds are produced as rapid sequences of clicks in the air passages of the head. These click ‘trains’, as they are called, are directed by the melon, which bulges and collapses, as needed, to focus sound. As sound bounces off objects in the water at ~1.6km/sec ( four times as fast as through air), the whales are able to use sonar to echolocate prey and help them navigate under the sea ice.

Hearing occurs mainly by bone conduction through the mandible (jaw), to the middle ear, inner ear, and finally to hearing centers in the brain. Whales may orient sounds by turning their heads from side to side.

Reproduction
Females become sexually mature at 4-7 years; males at 8-9 years of age. Mating occurs in the spring/early summer, and the gestation period is 14 months. A single young beluga is born in the water, and will stay with the female for two years; females may give birth every 2-3 years. Newborn calves are 1.5-2m long, a mottled beige colour. They soon turn dark gray, possibly providing protection in camouflage, and their skin lightens over their first 5-6 years of life, turning a bright white by adulthood.

Predators
Beluga whales are relatively slow swimmers, making them easy prey for killer whales. Over the winter, when breathing holes are few and far between, polar bears wait for them to surface along narrow cracks in the ice, dragging them out of the water with a powerful jaws and claws.

Despite massive hunting pressure in some areas, the greatest human induced threat to beluga whales is likely the presence of toxins such as DDT, PCBs and mercury in the food chain. These toxins accumulate in the fatty tissues of the whales, and are passed on to the young through mother’s milk.

- Article prepared by Carmen Spiech. A revised population estimate for the western Hudson Bay beluga whales was released this past year. Scientists believe that there may be as many as 59 000 whales in the bay. However, in light of hunting pressures and global toxins, the Department of Fisheries & Oceans is now considering adding the beluga whale to the Species At Risk list. A public consultation was held in Churchill this spring to discuss concerns regarding the proposed listing. A research project is also underway to study the interactions between tour boats and beluga whales in the Churchill River.