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Introduction

The beluga whale is perhaps one of the most recognizable cetaceans. Found in Arctic waters and as far south as the St. Lawrence River, belugas are one of the most classic North Pole animals that come to mind. They tend to be more coastal during the summer months, but by winter are found in the more open waters as sea ice builds.

Though born a grey color, belugas are a creamy white in adulthood, reaching maximum size at around 10 years old. With some sexual dimorphism, females grow to a max size of 13 feet, 2,600lbs while the males typically grow to 18 feet and 3,500lbs. Most of this weight comes from their fat: it accounts for 40-50% of their total weight, compared to on average 30% in other cetaceans. The thick fat, which can be up to 6 inches thick, is necessary for the frigid arctic waters in which they reside.

The beluga’s melon is one of its more distinctive features. Photo: Gregory Payan, Associated Press.

Belugas are also recognizable by their massive melon – the large, bulbous region at the forehead. Used for noise production and echolocation, the melon will actually visibly move when making these sounds! Another unique aspect in their head region is their ability to move and rotate their head, as their neck vertebrae are not fused like other cetaceans that would normally restrict their mobility. Belugas also do not have any dorsal fin, rather they have a dorsal ridge. The lack of fin is hypothesized as either a method of breaking sea ice with the solid back or lost the fin as a method in reducing heat loss in the cold waters.

Diet

Belugas aren’t picky eaters. They will eat octopus, squid, crabs, shrimp, clams, snails, sandworms, salmon, eulachon, cod, herring, smelt and flatfish, to name a just a few. Like most animals they will go where the food is, and will dive to depths and parts of the water column that have the best chances for finding their prey. Like other arctic species, the timing and amount of sea ice present affects their behavior. Belugas usually dive between 2-20 minutes to an average depth of about 164 feet. But after sea ice began declining, they increased the depth to an average of 210 feet; they also dove for longer more times per day. Belugas are looking for prey whose distribution and abundance may change as sea ice declines, thus the belugas alter their behavior to increase their chances of finding food.

Behavior

But their prey and ability to find food that isn’t the only thing that is affected; where and when belugas migrate is dependent on the timing of the formation and break-up of highly seasonal sea ice. In the spring the sea ice breaks up and allows access to open water, and in the fall that sea ice reforms, closing those areas (belugas occasionally get trapped by the sea ice if they haven’t left that area in time). Most populations migrate from over wintering areas to summer areas to feed and give birth, but this varies by population. For example, Bering sea belugas travel more than 1500 miles to spend their summers in Eastern Canada. In contrast, Cook Inlet belugas do not migrate at all and are found in Cook Inlet year round. Changes in sea ice have altered migration timing for some populations, but not others. Most interesting is that site fidelity and migration patterns are culturally transmitted – they learn it from their mothers!

Photo: Steve Snodgrass

Belugas may mate during that migration, or on their wintering grounds in later winter and spring. Females are sexually mature between 6-14 years, and males slightly older. They return to their birth areas each summer to calve in warmer, more shallow protected waters. Gestation is 15 months and they nurse for 2 years, having calves every 2-3 years. This continues for most of the female’s lifespan, which can be at least 70 years. Although pregnancy rates tend to decline after females reach their mid 40s, in northwest Alaska there was a 70 year old with a near term fetus, and the oldest female in Cook Inlet which had likely recently given birth was 47!

Living in groups from 2 to hundreds of individuals, belugas are a highly social species, with a complex social structure that researchers are just starting to tease apart. They live in a fission/fusion type society where they can live in groups that change often, but also have long-term bonds. Until recently it was thought that belugas have a structured matrilineal society, where groups are usually made up of maternally related individuals. But recent research in 2020 has shown this isn’t exactly the case. Most social groupings were comprised of kin and non-kin, many group members were paternally related rather than maternally, and some were unrelated. There can be single sex/age class groups to mixed age/sex groups and brief associations to multi-year affiliations (males will form long-term bonds with other males), where group composition and size may be context specific. But there may also be a more rigid multilevel society comprised of stable social units that regularly come together and separate. We still have a lot to learn about these beautiful animals!

Status

Belugas are listed as Endangered under the Endangered Species Act (ESA), and two specific populations (Cook Inlet and the Sakhalin Bay-Nikolaya Bay-Amur River stocks) are listed as Depleted under the Marine Mammal Protection Act (MMPA).

Populations worldwide are believed to number in the hundreds of thousands, but several stocks only have a few hundred animals. For example, the Cook Inlet stock of belugas is estimated to have around 279 whales as of the last NOAA count in 2018. This is an 80% decline in population since 1979, when the population numbered approximately 1,300 whales.

Threats

So what is causing this decline in certain populations? And what other threats do belugas face?

  • Habitat Destruction: Encroachment and global climate change have put the belugas’ environment at stake. Because they are heavily dependent on sea ice, they are very susceptible to harm through habitat degradation and destruction. This can occur through the creation of physical barriers that prevent or limit access to important areas, such as through coastal and offshore development. This increasing development in Arctic waters also poses more risks, including noise pollution, spillages, increased ship traffic, etc.
  • Contaminants: With their high blubber stores, belugas are particularly susceptible to toxic exposure from contaminant build-up. Contaminants enter the ocean system through runoff, oil and gas development, wastewater treatments, agriculture, and other industrial processes. They then bio-accumulate up the food chain, reaching maximum load in top-level predators such as belugas. Contaminant loads are typically highest in males, as they cannot offload contaminants to their offspring through their milk like females do. These toxins can impede reproductive ability, compromise immune function, and reduce the animal’s overall lifespan. They have also been associated with increased levels of cancer in St. Lawrence Estuary belugas in recent years.
  • Limited Prey: Overfishing, development, climate change, and habitat degradation have all cumulatively resulted in a reduction in prey available to belugas. As with any species, reduced prey puts the predator at risk of mortality due to decreased reproduction, emaciation, reduced immunity, etc., and may significantly impact population recovery of already depleted populations (such as those in Cook Inlet). Increased competition from other predators such as harp and grey seals may also be a factor in depleting prey stocks in areas such as the St. Lawrence Estuary.
  • Strandings: Although not super common, belugas do occasional strand. Typically strandings occur when molting, attempting to avoid predators or other threats (e.g. vessel traffic), or when animals are injured or suffering from disease. Often animals who are healthy can wait for the next tide and wriggle back into open water; however if animals are in reduced fitness already, they may not be able to survive until the next tide.
  • Ocean Noise: As already discussed, belugas are highly vocal creatures that depend on sound to feed and communicate. Thus anything that interrupts or impedes their ability to communicate could be a potential threat. In areas undergoing increased development, such as Cook Inlet, ocean noise is becoming more of an issue due to high levels of vessel traffic, development (including pile-driving and dredging), air traffic, military operations, and other human-related activities that are becoming more frequent.
  • Climate Change: Let’s talk about this huge one last! As we have already stated, sea ice distribution and timing is crucial for belugas. Any changes in these factors could result directly in death through entrapment, reduced prey availability, inability to access crucial areas, or lack of any ice which would change the ecosystem. Changing water temperatures and the impacts this has on oceanic currents may also significantly alter the environmental cues used by belugas for navigation and migration, making it more difficult for them to find these critical areas during their migrations.
Beluga whales trapped at ice hole. Photo: Sue Flood, WWF.

Fun Facts

  • The beluga’s Latin name, Delphinapterus leucas, literally means “white dolphin without a fin” – makes sense, right?! Their common name, beluga, comes from a Russian word “bielo” meaning white.
  • They are one of only two species in the Monodontidae family – the other is the narwhal.
  • Belugas are also called “sea canaries” due to their wide range of vocalizations. They emit chirps, whistles, grunts, moos, buzzes, and many more unusual and varied calls!
  • As many of you might know, we recently had a beluga whale here in the Puget Sound! The animal is thought to have come from the Beaufort Sea population, according to environmental DNA samples taken by NOAA scientists. Although thin, the animal was not thought to be emaciated. The last update on the lone beluga was in October 2021, so we’re not currently sure whether it is still around or has moved on. The last sighted beluga in Puget Sound waters was in 1940, when one was identified off Port Defiance.

cindy.elliser@pacmam.org

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