Adaptation Actions for a Changing Arctic: Perspectives from the Barents Area

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Adaptation Actions for a Changing Arctic: Perspectives from the Barents Area

The White Sea in Russia has breeding populations of several classically High-Arctic marine mammal species including white whales, harp, ringed and bearded seals. The harp seals are known to be a separate‘East Ice’population, which overlaps in range with animals breeding near Jan Mayen in the ‘West Ice’ when animals from both populations feed in the northern Barents Sea in summer.Walruses are also found in the southern parts of the Barents Sea region, in the Pechora and Kara Seas (Lydersen et al., 2012). Polar bears and walruses are known to be common biological populations across the north fromFranz Josef Land to Svalbard (Paetkau et al., 1990; Andersen et al., 1998), but other species found in both Archipelagos such as bowhead whale, white whale and narwhal, as well as the more southerly stocks of white whale and walruses are currently of unknown genetic affinity compared to those in the north. Grey seals ( Halichoerus grypus ) and harbour porpoises ( Phocoena phocoena ) are largely restricted to areas near the mainland coast,east across to the Pechora Sea in the case of grey seal. Harbour seals ( Phoca vitulina ) breed along the whole of the Norwegian coast across into Russia as far east as Murmansk. There is also an established population of some 2000 harbour seals in Svalbard,which is genetically distinct fromneighboring populations (Andersen et al., 2011; Merkel et al., 2013). Boreal-temperate species are already benefitting from climate change in northern areas of the Barents Sea. For example, harbour seals are increasing their distributional range in Svalbard and are also likely to be increasing in abundance (Merkel et al., 2013; Hamilton et al., 2014; Blanchet et al., 2015). Distributional changes in response to higher temperatures and less sea ice are already being documented routinely in the Barents Sea region for invertebrates, fish and top trophic animals including marine mammal species (Gilg et al., 2012). Additional examples of the latter include harbour porpoises being sighted in Svalbard in recent years, and sei whales ( Balaenoptera borealis ) becoming more routine at these high latitudes. Blue whales are now seen in the fjords of Svalbard from late spring well into autumn, extending their residency in the high north markedly in the last few years. However, competition from fish predators is thought to be limiting the abundance and distributional spread of some species such as minke whales (Bogstad et al., 2015). Globalization and growth in the volume of trade and tourism has provided some species with a solution for how to by-pass natural barriers such as ocean expanses, deserts,mountains and rivers.Some species of plants,animals,fungi andmicroorganisms have been transported across ecological barriers and become established in areas outside their natural range – these are defined as‘alien species’.Alien species that threaten ecosystems, habitats or resident species are defined as invasive alien species. These are considered one of the major threats to native biodiversity (UNEP, 2010) (see also Box 2.1). Within the Barents area, the first official effort to evaluate the risk posed by alien species and to document their impacts on the regions was the creation of the Norwegian Black List (2007), which assessed 217 species (Gederaas et al.,2007).A fewyears later,Gederaas and co-workers assessed all 1180 known reproducing alien species in Norway 2.2.3 Invasive alien species in terrestrial and marine environments

shifted closer to shore and sea ice is more fragmented. Harp seal pup production dropped by 50% between 2003 and 2005 in the White Sea, and was still at this low level during the last survey in 2013. The initial decline occurred during years of unusually bad ice conditions in the White Sea breeding areas, but subsequent ice conditions have generally been good within the White Sea. The decline also coincided with an increase in shipping activity in theWhite Sea, which may have affected the breeding areas directly during the first years (Zabavnikov et al., 2008) although no clear indications of significant shipping- related mortality were seen. Øigård et al. (2013) documented reduced body condition in molting Barents Sea harp seals caught in 2006 and 2011 compared to samples taken up to 2001. These authors suggested that recent low pup production in the White Sea may be due to reduced pregnancy rates caused by food shortage, mainly due to competition with the historically large cod stock (Bogstad et al., 2015). The recent declines in abundance and distribution of polar cod (Eriksen et al., 2014) are also likely to have played a role. Declines in environmental carrying-capacity for some marine mammal species are probably being masked in this region because of the vast levels of overexploitation in the past. For example, the Svalbard walrus population is currently increasing at near maximum theoretical limits, although breeding sea- ice conditions are declining, and spring/early summer ice conditions are likely to be causing the animals to spend longer periods on shore (Kovacs et al., 2014, 2015), limiting their feeding range. Similarly, polar bears in Svalbard have shown high adult survival and stable body condition (males) and production of yearlings from 1995 to present (Fauchald et al., 2015), although their primary sea-ice hunting habitat has certainly declined. Changes are clearly occurring in this population; some previous denning areas have been fully or partially abandoned due to loss of contact with the sea ice in autumn when females move into dens (Andersen et al., 2012). But, the artificially low density of bears in the region is likely to be slowing responses to climate change that are taking place in other polar bear populations. Migratory marine mammal species are important summer residents in the Barents Sea both because of the diversity of species in this community and their significant food requirements. Blue whale ( Balaenoptera musculus ), fin whale ( B. physalus ), humpback whale ( Megaptera novaeangliae ) and minke whales are regular seasonal occupants.The minke whale is the only commercially harvested cetacean species in the Barents Sea. Most of the other baleen whales have increased in abundance following the cessation of hunting for them a few decades ago; these species are certainly shifting their distributions northward as ice retreats and the open water season has extended (van der Meeren et al., 2014). A few toothed whale species are also seasonal migrants, including northern bottlenose whale ( Hyperoodon ampullatus ) and sperm whale ( Physeter macrocephalus ). Adult males of these two species regularly occupy high latitudes during summer, whereas females and young reside only in southern parts of the Barents Sea region (Christensen et al., 1975). Long-finned pilot whales ( Globicephala melas ) are particularly numerous and are important energetically because they feed on fish-eating squid; they occupy the southern parts of the region throughout the year, but extend as far north as Svalbard in summer.