As global warming increases, cold regions like the Arctic continue to experience great shifts in climate and environment. The effects of these shifts are closely observed in human populations, but how are different species impacted? A recent study examined white whales in Svalbard, Norway, and the climate change effects on their behavior and diet. Researchers looked at how reduced sea-ice formation and melting tidal glacier fronts influence the changes in habitat and movement patterns for this species.
White Whale Background and Observations
White whales, also known as beluga whales, can be found in the circumpolar Arctic. They’re known for their distinct white color and are one of the smallest whale species in the world. They are sometimes referred to as “sea canaries” for their high-pitched calls. With an estimated 150,000 individuals globally, they are listed on the IUCN Red List of Threatened Species. Some local populations such as those located in Cook Inlet, Alaska, are considered critically endangered.
These whales remain off the Svalbard coasts year-round. They live in sea-ice fjords and tidal glacier-front habitats. The fjords are sheltered from open-water predators, human activity, and extreme weather, making them particularly ideal for juvenile mammals. Tidal glacier-fronts are prime foraging areas for the whales. These regions have fresh water ideal for polar cod and capelin, two fish that make up a large part of white whale diet.
White whales migrate seasonally, some travelling 10s of kms, others as far as several hundred. During the warm summer season, sea ice in the fjords melts, providing an opportunity for the whales to move and feed in this region. Sea ice formation in the winter pushes the whales out toward the glacier-front habitats, where they spend most of their time during the colder season.
Methodology and Sampling
Increased warming is expected to negatively influence the environmental composition of this region. Svalbard has the greatest decrease in seasonal sea-ice cover in the circumpolar Arctic region. Rapid increase of air and sea water temperatures over the last two decades are the major contributing factors to this change. According to researchers, glacier-front melting and the associated reduction of foraging habitat could lead to changes in diet. Less sea-ice formation in fjords and warmer seasons could also affect biodiversity in these habitats. Could this mean white whales will need to migrate elsewhere for feeding during warmer seasons?
Researchers in this study compared habitat and movement changes of white whales, before and after major warming induced changes in the environment. They believed these changes began in 2006, so the two study periods were 1995-2001 and 2013-2016.
Fortunately for the researchers, satellite data from earlier years was available. They used satellite tracking to take measurements of whale movement patterns for the later period, and were then able to compare movement patterns for both periods. To track movement, white whale groups were live-captured using a nylon net and then tagged.
GlacierHub interviewed Kit M. Kovacs, one of the study’s authors and a senior research scientist at the Norwegian Polar Institute. Kovacs explained that choice of methods reflected concerns for animal welfare as well as data gathering. Groups without calves were netted, to prevent possible injury to young whales, she said. A total of 38 adult individuals were sampled for the study, 34 of them being male. Kovacs also explained that the females travel with their young, while adult males tend to travel in all-male groups, which would explain the sampling bias.
Research Findings and White Whale Resiliency
Results showed that during the later tracking period, the whales continued to remain close to the Svalbard coast. Scientists found this behavior to be striking, particularly when looking at populations in other areas that move long distances. The whales remain close to Spitsbergen, one of the largest islands in Svalbard. They move from the west coast fjords in the summer toward the east coast in the winter. The greatest distance of movement occurred when individuals were forced off the coast by the winter formation of landfast sea ice.
Some changes in habitat were observed. Whales were found to spend much time in glacier-front habitats for both periods, although they now spend more time out in the fjords. Less sea ice formation in the fjords has allowed for an influx of fish species that prefer the warmer waters. Arctic fish, particularly polar cod, have declined in numbers in this habitat, and are being replaced by Atlantic cod, haddock and herring. This new fish composition could be attracting the whales to fjords during the warm season.
Kovacs explained how a change in diet could affect the whales. “White whales use a pretty broad array of food types across their range, so it is unlikely to be a big deal for them to switch to new fish types. They might have to eat more, if the new fishes have a lower fat content, just to keep the same energy intake. As long as enough are available, it should not change their annual intake,” she said.
The white whales’ ability to consume a variety of food resources proves to be beneficial to the species. This helps them build resilience against some of the extreme effects of warming. The beluga may be able to adapt to an environment with less ice than in the past due to this dietary flexibility. Other species may not be so fortunate.