Beluga whales are distributed globally in the northern hemisphere (Hobbs et al., 2019). They live in the Arctic Ocean (Alaska, Canada, Greenland, and Russia) and adjacent waters, including sub-Arctic stocks in southern Alaska and eastern Canada (Figure 1). In Alaska, their range extends from the Arctic, through the Bering Sea as far south as Bristol Bay, and within Cook Inlet where the local stock is listed as endangered under the US Endangered Species Act. Within the state of Alaska, there are five recognized stocks of beluga whales, counter clockwise from the north: Beaufort Sea, eastern Chukchi Sea, eastern Bering Sea, Bristol Bay, and Cook Inlet (Hazard, 1988; O’Corry-Crowe et al., 1997, 2018). In the western Pacific Ocean, beluga whales are generally not seen farther south than the waters surrounding Sakhalin Island in the Sea of Okhotsk (Artyukhin and Burkanov, 1999) and in the eastern Pacific, farther south than Yakutat Bay on the Alaska mainland coast (~ 59° N) (Laidre et al., 2000; Lucey et al., 2015). Gray whales (Eschrichtius robustus) have migrated from Russia to the western US, so this geographic region was also considered a possible source of the lone Puget Sound whale before eDNA testing was completed.

Beluga whales are not considered normal inhabitants of the Salish Sea, the inland waters of Washington State, USA and British Columbia, Canada (Gaydos and Pearson, 2011). Thus, it was newsworthy when a lone beluga whale was sighted in the southern portion of the Salish Sea on 3 October 2021 by a group of citizens on a private recreational boat. They observed and recorded a completely white cetacean in Commencement Bay, Tacoma (Figure 2). The video recording was shared with the Orca Network Sighting Network that evening. Based on the color, size, and surfacings, the sighting was confirmed to be that of an adult or sub-adult beluga whale.

The following day, 4 October 2021, the whale was re-sighted off west Seattle in Elliott Bay. The next day, on 5 October, it was sighted and photographed near the naval shipyard in Sinclair Inlet. Because this whale was initially suspected to be a possible member of the endangered Cook Inlet, Alaska stock of beluga, NOAA Fisheries West Coast Region (https://www.fisheries.noaa.gov/region/west-coast) initiated and coordinated a health assessment response to try and gather as much data on this animal as possible. Thus, on 7 October, a team of biologists and veterinarians from World Vets, North Gulf Oceanic Society, Washington Department of Fish and Wildlife , SR3 , and Beam Reach Marine Science collectively launched three boats to obtain photo-identification images, observe the whale’s behavior, conduct a visual health assessment, opportunistically collect biological samples including feces and seawater for eDNA (environmental DNA) isolation, and acoustic recordings.

In the presence of the small research vessels, the whale displayed erratic, unpredictable movements with no consistent direction of travel, making it challenging to consistently observe and sample this animal. When spotted, the whale was intermittently observed for 10-20 minutes to allow sufficient time to collect data and observe the whale’s behavior and physical appearance. Given the challenge of locating the whale in a large area such as southern Puget Sound and its unpredictable movements, the response teams were on the water for a total of approximately five hours in order to collect basic health data. The whale was determined to be an adult of unknown sex and weight (Figure 3). Three Stranding Network veterinarians were part of the response team on October 7th and believed the animal to be thin, but not emaciated. No obvious injuries were noted. Hydrophones were deployed during the 7 October response, but only recorded ship noise.

Many digital photographic images were taken during the assessment and shared with two beluga photo-ID catalog points of contact at NOAA Fisheries and the Cook Inlet Beluga Whale Photo-ID Project (Dr. Tamara McGuire and Ms. Amber Stephens), but no photographic matches were made to the pre-existing catalogs.

A surface seawater eDNA sample was collected during the October 7th encounter by filling a 2.5-L soft-sided plastic canteen with seawater to collect genetic material (e.g., shed skin cells) from the beluga, from an area where the whale had very recently surfaced. The eDNA sample was delivered soon after to the NOAA Fisheries’ Northwest Fisheries Science Center in Seattle for analysis to generate genetic sequence data to help determine the beluga’s stock of origin. Geneticists at the NOAA Fisheries Conservation Genetics Lab filtered the seawater sample and successfully sequenced a fragment of the mitochondrial genome. The short sequence was identical to published DNA sequences from beluga whale samples previously sampled in the Beaufort Sea and the high Arctic, north of Alaska (O’Corry-Crowe et al., 2002, 2018). The genetic pattern did not match DNA sequences from belugas in the endangered Cook Inlet stock near Anchorage nor the beluga group near Yakutat, resulting in an “extremely low” likelihood that the whale was from either area (O’Corry-Crowe et al., 2015).

The whale appears to have traveled thousands of kilometers from the Beaufort Sea and Arctic Ocean through the Bering Strait, Bering Sea, and Gulf of Alaska to reach Puget Sound. The animal could have come from even farther away, as its sequence matched stocks from throughout the high Arctic, so its exact origin remains unknown. Depending on the route taken, estimates of the distance traveled range from 5200 - 8100 km (Figure 4).

The whale was re-sighted multiple times in Washington State (Figure 5). It was most frequently observed near busy locations, such as Commencement Bay (Port of Tacoma), Elliott Bay (Port of Seattle), the Bremerton naval shipyard, and then around Mukilteo near a Washington State Ferry terminal. The last confirmed sighting, off Lagoon Point, west side of Whidbey Island, was on 14 October 2021. An unconfirmed sighting on 13 November was reported off Newport, Oregon. Based on all available sighting information, the beluga whale spent at least 18 days within the Salish Sea. The concentration of sightings of the animal in these populated areas may reflect the large number of people using the areas, potentially biasing sighting frequency in these locations compared to more rural areas.

Natural history of beluga whales

Physical features

Beluga whales possess a thick layer of blubber that accounts for up to 40 percent of their body weight, helping them live in the freezing waters of the arctic and subarctic environment (Stewart and Stewart, 1989). They do not have a pronounced rostrum, or beak, and the top of their head is distinguished by a round, bulbous, flexible “melon” (Stewart and Stewart, 1989). The genus name Delphinapterus translates to “dolphin without a fin.” In place of a dorsal fin, beluga possess a sturdy dorsal ridge, allowing them to swim easily under ice floes or break through the ice for breathing holes. Some beluga stocks molt their outer layer of skin annually each summer (Suydam, 2009). To aid in molting, they may rub against coarse gravel in shallow waters to help eliminate the old, yellowed skin layer. Unlike other cetaceans, whose cervical neck vertebrae are fused, those of beluga are not, so they can nod or bend and move their heads from side to side (Stewart and Stewart, 1989).

The beluga whale is a medium-sized odontocete, 3.5-5.5 m long and reaches a mass of up to 1,500 kg (3,300 lbs). This species exhibits moderate sexual dimorphism, with male adults ~25% larger than females (O’Corry-Crowe, 2009). Beluga whales are born dark grey. Their skin color lightens as they age, becoming white as they reach physical maturity. They can reach a lifespan of 70 to 90 years of age (Burns and Seaman, 1986; Ferguson et al., 2020).

Habitat

Belugas are typically found in coastal waters during the summer months, often in shallow depths (i.e., 1-2 m). During other seasons, they may be found in deeper, offshore waters in some regions. Beluga inhabit coastal bays and inlets and can move between salt and freshwater. They are capable of diving to depths of 1,000 m for periods of up to 25 minutes (Martin et al., 1998; Richard et al., 2001). Beluga also seasonally inhabit estuaries and large river deltas to feed on fish runs, and are thus well-adapted to both cold ocean waters (e.g., amongst ice floes) and relatively warmer freshwater habitats (Loseto et al., 2006; Goetz et al., 2007).

Diet

Feeding preferences vary, depending on the season, geographical location, preferred prey availability, as well as the particular beluga stock (Choy et al., 2020). In Alaskan waters, Cook Inlet beluga feed on Arctic cod (Boreogadus saida), capelin (Mallotus villosus), eulachon (Thaleichthys pacificus), salmon (Oncorhynchus spp.), marine worms and squids and many other prey species (Quakenbush et al., 2015; Nelson et al., 2018). In the Arctic waters of Quebec, Canada, beluga depend on crustaceans, arctic char (Salvelinus alpinus), Greenland cod (Gadus ogac), and arctic cod (Breton-Honeyman et al., 2016). In the St. Lawrence River, Canada, capelin, American sand lance (Ammodytes americanus), marine worms and squid are common prey items.

Reproduction

Beluga are thought to mate during late winter and spring. Mating may occur on wintering grounds or during migration dependent on the specific stock (Cosens and Duek, 1991; Suydam, 2009; Lomac-Macnair et al., 2015; Shelden et al., 2019). Females reach sexual maturity at about 6 to 14 years old, and males when they are slightly older. Gestation is approximately 15 months, but can go as long as 475 days (15.8 months), with calves nursing for at least two years (Robeck et al., 2005). Females typically give birth every two to three years. Since newborn calves lack a thick blubber layer to insulate them from the cold, births will generally take place during the summer months where the water is relatively warm such as shallow tidal flats or estuaries, where there is also more protection from predators, and opportunities to take advantage of spawning fish runs (Smith, 2007; Suydam, 2009; Krasnova et al., 2012; McGuire et al. 2020).

Threats

Beluga whales are exposed to a number of stressors and threats, that may include any of the following: pollution (e.g., chemicals, plastics), habitat degradation, shipping, natural resource exploration and development, reduced prey availability, extreme weather events, strandings, predation from marine predators such as killer whales (Orcinus orca) and polar bears (Ursus maritimus), underwater ambient noise, subsistence harvesting (particularly of smaller stocks), and other types of anthropogenic disturbances (O’Corry-Crowe, 2009; Norman et al., 2016).

Extralimital sightings on the US west coast

Though the recent sightings of the beluga in the Salish Sea were very unusual, extralimital sightings are not entirely uncommon on the east coast of the US where belugas have been reported off Massachusetts and New York. Extralimital sightings along the US west are reported less frequently.

In Hoonah Sound, in the Alexander Archipelago of southeast Alaska, a lone beluga was sighted in the spring of 2021. A relatively poor quality video of the beluga, recorded from a boat, was forwarded to NOAA Fisheries in Alaska on June 1st. A second beluga was sighted, from the air, near Seward Fox Island (Resurrection Bay), one mile south of Southern Spit  on 7/27/2021 by Seward Air Taxi. It was reported alive and swimming and did not appear distressed. The reporting party submitted photos to NOAA Fisheries for species confirmation.

A beluga was previously sighted in the Salish Sea, Washington State, in 1940 near Point Defiance (Scheffer and Slipp, 1948). There were multiple reports of this animal in the spring, but also fall observations near Steilacoom, a small town 13 miles southwest of Tacoma, suggesting it may have been the same whale.

Additionally further south, a lone free-ranging beluga whale was sighted off Mission Bay near San Diego, California on 26 June 2020. A deceased pure white whale was found off Laguna Ojo de Liebre, Baja California Sur, Mexico, on October 3 and was presumed to be the same whale spotted earlier off San Diego. Because a necropsy was not performed, its stock identity was not determined; however, a skin sample was obtained and plans are to send the sample to a lab in the US for genetic analyses. 

Conservation and current U. S. legal status

Belugas were listed as "vulnerable" by the International Union for Conservation of Nature (IUCN) before 2008. In 2008, the beluga was reclassified as "near threatened" by the IUCN due to uncertainty about threats to their numbers and the number of belugas over parts of its range (especially the Russian Arctic). Worldwide, there are approximately 21 stocks of beluga whales, with an estimated 200,000 individuals (Hobbs et al., 2019). In June 2017, the status of beluga stocks worldwide was reassessed to the level of "Least Concern" on the IUCN Red List (Lowry et al., 2017). The exception to this classification is the non-migratory Cook Inlet stock in southcentral Alaska, which is a separate stock that is listed as "Critically Endangered" by the IUCN as of 2006 (Lowry et al., 2019) and as "Endangered" under the Endangered Species Act as of October 2008 (U.S. Federal Register, 2008). The Cook Inlet stock is one of five in Alaska, the remainder not considered to be threatened or endangered at this time (Beaufort Sea, Bristol Bay, Eastern Bering Sea, and Eastern Chukchi Sea)(Muto et al., 2021). The most recent estimate in 2018 by NOAA Fisheries suggested that the stock numbers approximately 279 individuals (Shelden and Wade, 2019).

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