Determining the species assemblage and habitat use of cetaceans in the Svalbard Archipelago, based on observations from 2002 to 2014

Abstract

This study used 13 years of cetacean sighting data (2002-2014) from waters around the Svalbard Archipelago to determine key habitats for year-round resident species as well as seasonally resident species, and to explore spatial overlap between these groups via a combination of kernel density estimation and Maxent modelling. The data set consists of observations made by research vessels conducting various marine studies, coast guard ships and marine-cruise tourist operators. Data are reported from the seasonal period in which there is daylight (March-November), though 95% of the observations occurred June-September. Changes over the study period were investigated, within the limits of the data, to explore whether range shifts may be occurring. Fifteen cetacean species were reported. Among the resident ice-associated cetaceans, only white whales were reported frequently; they were seen exclusively in coastal habitats, in accordance with their known use of tidal glacier fronts for feeding in this region. Narwhal and bowhead whales were rare. Seasonally resident minke whales, fin whales, humpback whales, blue whales and sperm whales as well as small dolphins were seen frequently, in broad and somewhat overlapping habitats. Other less common seasonal residents included killer whales, northern bottlenose whales and sei whales; harbour porpoises and long-finned pilot whales were also reported, but rarely. Shifts over the study period towards higher latitudes, and into coastal environments, were observed for several seasonally resident species. These expansions are likely linked to warming ocean temperatures and a precipitous decline in sea-ice cover in the area.

First abundance estimate for white whales Delphinapterus leucas in Svalbard, Norway

“…During the survey, all sightings occurred in the COAST stratum. This result is consistent with the coastal behaviour of white whales in Svalbard, which has been documented in tracking studies as well as in the marine mammal sighting database run by the Norwegian Polar Institute (NPI) (Lydersen et al 2001, Storrie et al 2018, Vacquié-Garcia et al 2018). In addition, most sightings of white whales during this survey occurred close to glacier fronts (Table 1).…”

“…If an offshore 'ecotype' did exist in this region, or if females behave differently than males in terms of use of offshore areas, the survey could potentially underestimate the stock size. However, no animals were sighted on any of the offshore lines during the survey, and significant offshore effort by various research programmes and tour operators well beyond the 12 km limit used in this survey consistently report to the NPI Sighting Database a lack of white whales offshore (see Storrie et al 2018). Thus, it is unlikely that longer offshore lines would have resulted in a significantly larger number of sightings during the survey effort.…”

“…a missed group in the OPEN OCEAN strata), this estimate suggests that the Svalbard stock is one of the smallest white whale stocks in the world. This small number is somewhat surprising given that white whales are one of the most commonly observed cetaceans in the Svalbard area (NPI Marine Mammal Sighting Database; Storrie et al 2018). However, these whales are relatively easy to spot because they are white, they often occur in groups and travel very close to the coast.…”

“…Since the 1960s, when the whales were de scribed as being severely depleted and 'commercially extinct', the stock has been totally protected in Svalbard (Gjertz & Wiig 1994). Despite the large number of animals caught in the past, white whales are one of the most commonly observed cetaceans in this area (Storrie et al 2018). In recent years, the habitat use of white whales in Svalbard waters has been investigated using satellite tracking, which has revealed that they are year-round residents and occupy areas close to the coast (Lydersen et al 2001, Vacquié-Garcia et al 2018.…”

Atlantic Water Pathways Along the North‐Western Svalbard Shelf Mapped Using Vessel‐Mounted Current Profilers

“…Such circulation is important for bringing warm AW onto the shelf in the deeper trenches. The Hinlopen region is a hot spot for marine mammals (Storrie et al, ), which might be linked to the supply of AW facilitating suitable habitat conditions.…”