The mysteries of the beluga whale
Beluga whales are distributed through the high latitudes of the Northern Hemisphere, from the west coast of Greenland to Svalbard. Male adult beluga whales weigh up to 1,600 kg and females on average weigh around 1,430 kg. Adult beluga whales can reach lengths of up to 6 metres, but the average length is 4 metres. Their average lifespan is between 35-50 years, however the theory of using one growth layer per group of teeth indicates they may even live up to 60-70 years. They can dive up to 25 minutes: research conducted by two United States Arctic Ocean beluga populations have shown the whales to be able to dive to depths of almost 900 metres.
Beluga whales in Svalbard © Elke Lindner - Oceanwide Expeditions
Beluga whales feasting on various dishes
The Beluga Whales you might spot on an expedition to Greenland feed on feed on a variety of dishes: various species of fish are considered to be their primary prey items including salmon, herring and Arctic Cod but they also feed on a variety of molluscs for example squid and octopus as well as crustaceans including shrimps and crabs. In return beluga whales are hunted by Polar Bears and Killer whales throughout the Arctic region. In total it is estimated that their population size is around 150,000 animals.
Beluga whales morph into casper-the-ghost-colour
The whales are born very dark grey or brownish-grey and gradually lighten up to white as they mature. Instead of having a dorsal fin beluga whales have a tough dorsal ridge. Unlike other cetaceans beluga whales can move their heads up and down and side to side because their cervical vertebrae is not fused. This enables them to catch prey in muddy or even ice-covered areas. The whales are extremely insulated for Polar conditions with a thick layer of blubber accounting for as much as 40 percent of their body mass. An interesting uniqueness about beluga whales is that they shed their outer layer of skin, or molt, each summer. The whales typically mate in the spring with gestation lasting around 14-15 months with calves usually born between March and September. They are considered to be extremely social animals that typically migrate, hunt and interact together in groups or singually. They are considered the ‘canaries of the sea’ as they have a vast repertoire of sounds including whistles, squeals, moos, chirps and clicks.
Beluga whale colours © Elke Lindner - Oceanwide Expeditions
Beluga whales’ numerous stomping grounds
The Beluga whales that you might spot during the summer on a Svalbard expedition will typically be found in shallow coastal waters (as shallow as 1-3 metres deep), although they do also appear in deeper offshore waters (800 metres). During the summer months they even migrate up estuary rivers with some individuals found hundreds of kilometres upstream from the sea. Along the coastline beluga whales typically occupy continental shelf and slope waters and deep ocean basins in conditions of open water, loose ice and heavy pack ice. During the winter months their preference is to be in shallow or coastal areas with light or highly moveable ice cover.
Tracking beluga populations
Satellite data has shown that beluga whales have a seasonal migration pattern of heading to fjords and estuaries during the summer month before migrating over the winter period to separate grounds. A recent study conducted by the University of Washington analysed and organised tracking data for 30 whales, recorded over the past 15 years. According to the lead scientist Donna Hauser ‘’this study gives us a benchmark of the distribution and foraging patterns for…two beluga populations’’: the two populations spending their winters in the Bering Sea, after which when the sea ice melts the whales travel north and spread out across the Beaufort and Chukchi seas. The scientists new tagging data confirms the whales prefer these areas due to the large abundance of Arctic cod with dive data showing beluga whales reaching depths between 650 and 1,000 feet where Arctic cod are commonly found. The study also found the beluga whales also reached the ocean bed in search of prey and their preferred depth depended on the topography of the sea floor. According to the University of Washington scientists the data will enable a baseline to be established for normal foraging patterns among the two beluga populations, enabling researchers to monitor the effects of rising sea temperatures on vulnerable marine mammals. In particular the study’s co-author Kristin Laidre stated ‘’the results of this work can not only be used to understand ecological relationships for arctic top predators, but also inform the management of beluga whales, which are an important subsistence resource for northern communities’’. One area of interest for future research is studying whether beluga whales will delay their autumnal return to the Bering Sea as the arctic stays unfrozen later into the year now.
Impacts of melting sea ice on beluga whales
Beluga whales have adapted well to life under the Arctic sea ice with many populations migrating from warmer waters to overwinter in areas with sea ice. However, in January of this year sea ice extent was just 5.2 million square miles, around 7.1% below the recorded average, a year after the Arctic Ocean recorded its lowest maximum ice extent. This will impact beluga whale populations in the Arctic in many unpredictable ways. For example, in a 28 year-long study conducted on beluga whales along western Greenland scientists found beluga whales migrated further out from shore to chase after receding ice sheet. However, with the receding ice comes a mortal danger to beluga whales: the Killer Whale.
Killer whales impacting beluga populations
Researchers have found that receding ice has meant Alaskan killer whales have expanded their range and are hunting more beluga whales. In 2013, a group of researchers travelled to Kotzebue Sound in Alaska to study beluga whales using underwater microphones and audio analysis. However, instead of belugas they found killer whales. Over a 70 day period they found beluga whales only three times, however killer whales were recorded nearly every day. According to a beluga hunter killer – traditionally, Inupiat hunters take to the ice in the spring to hunt beluga where the meat and fat would be distributed among community members and for many modern Inupiat communities in Alaska subsistence hunting and traditional food enables them to retain a link to their history and culture – whales have stayed out near the open ocean but in recent years they have ventured closed to shore and even ventured up a local river. According to Manuel Castellote of the U.S. National Oceanic and Atmospheric Administration’s National Marine Mammal Laboratory ‘’if there is a compromised population of belugas and killer whales take a couple, that could be enough for the population not to be able to recover…that could be reason enough for this population to stay within low numbers’’. Castellote also believes the presence of killer whales has changed the beluga whales’ behaviour with audio recordings suggesting the whales have become less conversational to avoid unwanted killer whale attention.
The mysteries of the beluga whale remain
Overall, scientists are unsure about many variables that could potentially impact beluga whale populations. For instance there has been speculation that during the summer months beluga whales in estuaries are enjoying the mixing of freshwater and coarse substrates that act as a ‘facial’ for them by facilitating skin shedding during molt. Researchers are also unsure why beluga whales like to move into deep, ice-covered waters. It could be due to avoid killer whales. Another hypothesis is that beluga whales move into ice-covered offshore parts of the sea to feed on Arctic cod. Nonetheless, scientists are pushing ahead to understand this fascinating specie of whale.