White whale/beluga whale (Delphinapterus leucas)

Marine mammals 2013
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The white whale/beluga whale is the most numerous of the three resident ice-associated Arctic whales in the Barents Sea. Similar to the other two high-arctic species, it can be found in high concentrations of drifting ice (>90% ice cover) in areas which are inaccessible to migratory species of whales. Satellite-tracking of white whales in Svalbard during summer and early autumn has shown a profoundly coastal distribution; tracking data from late autumn and early winter suggest that they remain close to these coastal areas, penetrating deep into extensive ice. During summer, they spend most of their time close to tidal glacier fronts in Svalbard or moving between them (Lydersen et al., 2001).

Presumably, this is due to abundant food in these areas linked to upwelling, or fresh-water osmotic shock to zooplankton which results in fish aggregations that include polar cod (Lydersen et al., 2014); this is thought to be the main food source for white whales in Svalbard (Dahl et al., 2000). Sightings, from the first daylight in March until the last daylight in November additionally, suggest that they remain local in Svalbard on a year-round basis. However, they have not been studied during the dark period, and no assessments have been conducted in Norwegian waters; a survey for this species is planned for 2017 at Svalbard. Aerial surveys and intensive long-term behavioural studies have been conducted on white whales in the White Sea. Some whales are believed to be resident throughout the year; however, there is an influx during summer and an outflux during winter; so some proportion of the White Sea population does migrate into the Kara Sea and the broader Barents Sea during at least part of their annual cycle (Andrianov and Lukin, 2008; Bel’kovich, 2008; Chernetsky and Krasnova, 2008; Glazov et al., 2008; Kuznetsov and Bel’kovich, 2008; Kuznetsova et al., 2008; Nazarenko et al., 2008). Whales in the White Sea tend to concentrate in shallow water areas (<50 m), with the highest densities in summer being found in Onega, Dvina, and Mezenskiy Bays (Glazov et al., 2008; Soloviov et al., 2008). White whales are observed along the south-eastern Barents Sea coast most frequently in May, and least frequently during winter. Stocks have not been well delineated in Russia (Boltunov and Belikov, 2002); but during summer numbers in the White Sea average 5,553 (CI – 15%, Solovyev et al. 2012). Some white whales are believed to migrate from the Barents Sea into the Kara and Laptev Seas during spring after the ice break up, and then to return northward during fall. The global population of white whales has not been accurately assessed, but this species likely numbers in the tens of thousands in the Svalbard/Barents Sea area. Less sea ice will likely result in increased killer whale predation on white whales in northern waters; there also may be changes in prey due to on-going declines in polar cod abundance. But, it is difficult to predict how this species will be affected by climate change given the varied ecological adaptations they display across their range (Gilg et al., 2012).

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