Cetacean spatial trends from 2005 to 2019 in Svalbard, Norway

Abstract

This study uses cetacean sighting data, acquired via a citizen science programme, to update distributions and spatial trends of whales and dolphins in waters around the Svalbard Archipelago during the period 2005–2019. Distributions, based on kernel density estimates, from an early period (2005–2019) and a recent period (2015–19) were compared to identify potential shifts in distribution in this area, which is experiencing rapid warming and concomitant sea-ice losses. Among the three Arctic endemic cetaceans, white whales (Delphinapterus leucas, also known as beluga) had a stable, coastal distribution throughout the study, whereas narwhals (Monodon monoceros) and bowhead whales (Balaena mysticetus) were observed only north of the archipelago, but with increasing frequency during the recent period. White-beaked dolphins (Lagenorhynchus albirostris) had a stable distribution along the continental shelf break, west and south of Svalbard. Sperm whale observations shifted from west of Bjørnøya during the early period to being concentrated around the north end of Prins Karls Forland, west of Spitsbergen during the recent period. The four summer-resident baleen whales—blue whales (Balaenoptera musculus), fin whales (Balaenoptera physalus), humpback whales (Megaptera novaeangliae) and minke whales (Balaenoptera acutorostrata)—have shifted their distributions from the continental shelf break west of Spitsbergen during the early period into fjords and coastal areas during the recent period. These changes coincide with increased inflows of Atlantic Water into the fjords along the west coast of Spitsbergen and across the north of the archipelago.

High Arctic “hotspots” for sperm whales (Physeter macrocephalus) off western and northern Svalbard, Norway, revealed by multi-year Passive Acoustic Monitoring (PAM)

“…At Isfjorden, the overall occurrence rate, while much lower than at Eastern Fram Strait, was still higher than expected. Previous studies have reported some sightings around the mouth of this fjord 16 , 17 , 19 , but in general sperm whales are not common in the area. Sperm whales are known to avoid ice-covered areas 6 , 11 , 35 and these two locations had the lowest overall ice cover of the eight sites during the deployment periods (Fig.…”

“…The Eastern Fram Strait location had the highest sperm whale occurrence in our study. While a visual survey from 1995 to 2001 did not report sperm whale sightings in the Eastern Fram Strait 42 , more recent studies from the same area do report their presence 14 , 16 , 17 , 19 . At Isfjorden, the overall occurrence rate, while much lower than at Eastern Fram Strait, was still higher than expected.…”

“…Despite low ice cover and some Atlantic Water influence, sperm whale occurrence was scarce and inconsistent in Kongsfjorden. A recent study reported an increase in sightings near the mouth of Kongsfjorden, so more acoustic detections could have been expected 19 . The location of the hydrophone approx.…”

“…This is likely explained by the inflow of warm Atlantic Water in the West Spitsbergen Current, which keeps western and northern Svalbard waters relatively ice-free for most of the year 18 . Recent studies report a possible northward shift in sperm whale distribution with more frequent observations at higher latitudes around Svalbard as the northern sea ice edge has shifted northwards in recent years 17 – 19 . Sperm whales have also been reported in the relatively shallow waters of the Barents Sea, east of Svalbard, and strandings have occurred on the mainland in the western Russian Arctic 20 .…”

An observation of white whale (Delphinapterus leucas) mating behaviour in the wild

“…Twenty-one stocks are currently recognized (Hobbs et al 2019); one of these resides around Svalbard, Norway. This is one of the smallest stocks, which was recently estimated to number 549 individuals (95% confidence interval: 436−723; Vacquie-Garcia et al 2020), although white whales are the most commonly observed cetacean in Svalbard (Storrie et al 2018;Bengtsson et al 2022). Reasons for this seeming discrepancy include the fact that white whales are easy to spot and spend most of their time in the summers in coastal waters off the west coast of Svalbard, where their distribution overlaps with people (Vacquie-Garcia et al 2018).…”