Expected increased temperatures related to climate change will likely affect growth rates and other biological processes. This may cause competitive conditions to change between cold-adapted bacteria and bacteria adapted to warmer waters (Børsheim and Drinkwater 2014). Consequently, the species composition of bacterial communities may also change as temperatures change.
Among phytoplankton species in the Barents Sea, there tends to be large inter-annual and geographical variation in patterns of distribution and abundance. However, the overall annual pattern of succession is quite stable, despite variability between years for abiotic factors such as temperature. Formation of the spring bloom varies between years, and is largely determined by the degree of stabilization in upper layers of the water column.
During August and September of 2013 in the Norwegian sector of the Barents Sea, the average mesozooplankton biomass was clearly below the long-term average. During 2008-2012 in this region, estimates of average biomass were relatively stable and slightly above 6.0 g dry weight m-2, although the 2012 Norwegian data was less certain than in previous years. In 2013, highest mesozooplankton biomass in the Norwegian sector was observed north-east of Svalbard and in Atlantic Water masses in the south-west — where transport of zooplankton from the Norwegian Sea into central and western parts of the Barents Sea occurs.
Horizontal distribution of mesozooplankton biomass in 2013 is shown in Figure 4.3.2. Patterns of distribution have been similar between years, even though the area of survey coverage may vary. Particularly low biomass was observed in central parts of the Barents Sea. In westernmost areas southeast of Bear Island, slightly higher zooplankton biomass was observed — somewhat similar to what was observed in 2009 and 2010. Another area with high mesozooplankton biomass was observed in the Russian sector of the Barents Sea, west of Novaja Zemlja and east of 25°E.
Samples were collected by PINRO in the Barents Sea during the 2011-2012 autumn bottom-trawl survey to estimate pre-winter euphausiid assemblages. During 2012, further decrease in the abundance of euphausiids was recorded in some areas; at the same time their abundance increased in other areas. However, euphausiid abundance generally remained above the long-term mean in all areas of the Barents Sea (Figure 4.3.7).
Estimated abundance of large gelatinous zooplankton was higher in 2013 than in 2012. The center of distribution and highest abundance was located in the central to south-western part of the Barents Sea in 2013; a quite typical pattern consistent with observations from 2008 until present. During this period, occurrence of “jellyfish” has overlapped significantly with regions of low mesozooplankton biomass.
More than 3,050 invertebrates species inhabit the Barents Sea benthos (Sirenko, 2001) and boreal-arctic species dominate in terms of biomass. Benthic areas with low abundance (less than 1,000 individuals/ m2) and biomass (less than 10-25 g/m2) are usually restricted to bottom depressions such as the western deep-water areas in the Bear Island Channel (Bjørnøyrenna) and Hopen Deep (Hopendypet) (Figure 4.3.11), deep-water areas between Franz Josef Land and shallow waters of the Novaya Zemlya Bank and deep-water areas in the Eastern Basin (Øst bassenget sør, Figure 4.3.11).
The Barents Sea is subjected to a number of pressures (Figure 4.3.23) which are expected to have an effect on the megabenthos. These pressures include: 1) the non-indigenous snow crab, which may become a dominant species in a continuously spreading zone; 2) the influx of warm Atlantic waters into southwestern and possibly northwestern regions which may change the
Zoobenthic monitoring in the Kola section is one of the most published and extensive monitoring programs in the Russian Arctic. Data collection was initiated in the early 20th century by the Marine Biological Station, in Alexander Harbor of the Kola Bay. Modern benthic investigations in the Kola Section have been conducted by the Murmansk Marine Biological Institute (MMBI) since 1995. PINRO joined the monitoring program in 2003 using methods comparable to the existing long-term monitoring series. Since 2010, PINRO and MMBI have collaborated to ensure increased sampling regularity, greater speed in data processing, and more accurate taxonomic identification.
Recent ocean warming has caused some commercial fish species to expand northward. This includes the Atlantic cod (Gadus morhua), which has recently been recorded north to 82ºN on the edge of the Barents Sea shelf to the Arctic Ocean (Johansen et al., 2013; Kjesbu et al., 2014).
Three species of wolfish — Atlantic wolffish (Anarhichas lupus), Spotted wolffish (Anarhichas minor), and Northern wolffish (Anarhichas denticulatus) — live in the Barents Sea. The abundance and biomass of all three species is relatively low (Figure 4.3.48), but they are all widely distributed throughout the Sea. The stock size of Atlantic wolffish and spotted wolffish, as measured by area-swept-clear estimates, has been relatively stable since 2004; the Northern wolffish has varied between 35,000
During the recent warming period (1998-2012), distinct trends were observed in abundance of fish species from different zoogeographic groups (Figure 4.3.54). The abundance of coldwater fish species (Arctic, mainly Arctic, and Arcto-boreal) decreased during the period between 2000 and 2010. However, a trend of slight increase has been observed since 2010 in the abundance of mainly arctic and Arcto-boreal groups.
The 2013 saithe assessment was not accepted by ICES, but national advice was provided to Norwegian authorities by IMR. SSB has decreased in recent years, and fishing mortality has increased (Figure 4.3.53). The 2014 TAC was set at 119,000 tonnes based on national advice; this represents a 15% reduction from 2013 (ICES AFWG, 2014).
Based on the most recent estimates of fishing mortality and SSB, ICES classifies the stock as having full reproductive capacity and being harvested sustainably. SSB increased to a historic high in 2003, and then decreased; there is evidence, however, that SSB is now increasing again. Blue whiting is not fished in the Barents Sea; however a TAC is set for the entire Northeast Atlantic region. Total landings in 2012 were estimated at 384,000 tonnes.
The polar cod stock is presently at a low level of abundance (Figure 4.3.51). Norway conducted commercial fisheries for this species during the 1970s; Russia has fished this stock on a quite regular basis since 1970. Nevertheless, for many years the fishery has been so small that it is believed to have little impact on stock development. Stock size has been measured acoustically since 1986, and has fluctuated between 0.1-1.9 million tonnes.
Based on the most recent estimates of SSB and fishing mortality, ICES classifies the stock as having full reproductive capacity and being harvested sustainably. The 2002 and 2004 year classes dominate the current spawning stock which is estimated to be 5 million tonnes in 2013. The year classes 2005-2012 are all below average, while the 2013 year class is around average. The abundance of herring in the Barents Sea is believed to be at an intermediate level in 2014.
Capelin stock size has been stable since 2008 (Figure 4.3.49). Spawning stock size in 2014 was predicted from September-October 2013 acoustic survey data in combination with results from a model — estimating maturity, growth, and mortality (including predation by cod). The model accounts for uncertainties in both survey estimates and other input data. At catch levels below 65,000 tonnes (during spring 2014), the probability of SSB falling below 200,000 tonnes was less than 5 %.
Greenland halibut is widely distributed in the Barents Sea. Catches are highest along the continental slope where the main spawning grounds are located (Figure 4.3.45). The northern and north-eastern part of the Sea is regarded as a nursery area for the stock (Figure 4.3.46). This species is also relatively abundant in many of the deep channels running between shallow fishing banks of the Barents Sea (ICES AFWG, 2014).
For more than a decade, recruitment failure has been observed in Barents Sea redfish stocks (Figure 4.3.42); but signs of improvement have been observed recently. With this understanding, it is important that juvenile age groups are given the strongest protection from being caught as bycatch in any fishery, e.g., shrimp fisheries in the Barents Sea and Svalbard area where significant numbers of young redfish often occur (Figure 4.3.43). This will ensure that the recruiting year classes can contribute as much as possible to stock rebuilding (ICES AFWG, 2014).
Based on the most recent estimates of SSB (Figure 4.3.40), ICES classifies the stock as having full reproductive capacity, but also in danger of being harvested unsustainably. Fishing mortality has fluctuated around FMSY (0.35) during the last 10 years, but has increased considerably since 2010 and is now above Fpa. Very strong year classes (2004-2006) recruited to the fishable stock in 2008-2010; thus, the stock in 2010-2011 reached the highest level observed in the time series that goes back to
Based on the most recent estimates of spawning stock biomass (SSB), ICES classifies the cod stock as having full reproductive capacity and being harvested sustainably (Figure 4.3.38). The SSB has been above Bpa since 2002 and is now at a record high level, while the total stock biomass is at a level not seen since the early 1950s. Currently the stock is dominated by large individuals from the very abundant 2004-2006 year classes; these year classes largely support the current fishery (ICES AFWG, 2014).
Bearded seals have a patchy distribution throughout the Arctic, occurring at low densities throughout their range. They are largely solitary, but small groups can be seen during late spring and -early summer, when they are breeding,breed and then moultingmoult/molt, and the sea-ice cover is restrictedlimited. Bearded seals can maintain holes in relatively thin ice, but avoid densely packed ice unless open-water leads are available.
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).
White-beaked dolphins are the only dolphin to remain in the Barents Sea Region on a year-round basis. They are found throughout the North Atlantic, primarily in shelf waters, but they canmay also inhabit offshore areas of intermediate depths. During summer, they can be found north to the ice edge. They are commonly sighted in coastal waters around Spitsbergen in summer, as well as in the pelagic parts of the Barents Sea, but are most common in the southern Barents
Among the toothed whales, the long-finned pilot whale, sperm whale, the northern bottlenose whale, and killer whales are summer visitors to the Barents Sea. The Northeast Atlantic population of long-finned pilot whales number some 780,000 individuals (NAMMCO 1998), but only a very small (and unknown) part of this population enters the Barents Sea. Few sightings have been made in areas covered by IMR surveys; these sightings are insufficient to estimate
Killer whales occur in all world oceans and most seas, but their relative scarcity and sporadic occurrence make them difficult to census in the Barents Region. Photo-identification techniques have been used to recognise >400 individuals in northern Norway. Coastal killer whales are tightly linked to the availability of herring. During winter, killer whales aggregate in and around Vestfjorden in Lofoten, foraging on over-wintering herring.
Among the baleen whales that frequent the Barents Sea on a seasonal basis, the minke whale is the most numerous. Recent estimates suggest that the population is quite stable (Solvang et al., 2015), although minor variations do occur in both distribution and point estimates. The most recent point estimate for minke whale abundance in the total area is numerically lower than previous estimates, but not significantly different from estimates based on the two preceding
Fin whales and humpback whales are the second and third most abundant baleen whales in the Barents Sea, respectively. Both are fast-swimming, migratory species that over-winter in the south and occupy the Barents Sea during the productive summer months. The summer activity of these whales is dominated by feeding and during most of the winter; they are thought to fast while they are breeding. In the Barents Sea, fin whales generally inhabit deeper areas along
Blue whales are also summer residents in the Barents Sea. They probably number 600-1,500 individuals in the North Atlantic. In recent years, this species has been sighted frequently in Svalbard waters, up the west coast at the shelf edge as well as north of Spitsbergen. Similar to the fin whale, it also enters deeply into Svalbard fjords. It is sighted from early summer until late fall, and appears to be extending is seasonal presence in the northern Barents Sea
Small cetaceans that frequent the Barents Sea include bottlenose dolphins, common dolphins, white-sided dolphins and white-beaked dolphins. All but the latter occur in the southern Barents Sea, particularly along the shelf break and over oceanic banks and ridges, but must be considered vagrants in the region. White-beaked dolphins are the only small cetacean species that routinely occupies the region more broadly.
Hooded seals form one stock in the Northwest Atlantic and another in the Northeast Atlantic; although, recent genetic studies suggest no biological distinction between the groups (Coltman et al., 2007). In the Northeast Atlantic, whelping takes place in mid-late March in the West Ice, not far from where the West-Ice harp seals give birth. Between breeding and the moult, hooded seals carry out feeding excursions to the continental shelf edge off the Faroe Islands and Northern Ireland and to areas in the Norwegian Sea.
Harp seals are migratory and have a much wider distribution range than ringed seals, bearded seals, and walruses; they also have a more pelagic life history (Lavigne and Kovacs, 1988; Haug et al., 1994a). Three different populations inhabit the North Atlantic: the Northwest Atlantic population off Canada’s east coast; the Greenland Sea (West-Ice) population which breeds and moults just north of Jan Mayen; and the East-Ice population which congregate in the White Sea to breed.
Coastal marine mammal species in the Barents Sea include harbour seals, grey seals, and the harbour porpoise. Larger whales also migrate along the coast on their way north to the take advantage of the summer burst of productivity in the Barents Sea. The harbour seal is a coastal species that is found both in the Atlantic and Pacific Oceans. Harbour seals are gregarious, hauling out to rest on land at low tide every day of the year, in groups ranging from just a few animals up
The bowhead whale is the only baleen whale that resides in the Arctic throughout its life. It is highly adapted to its ice-associated lifestyle, possessing a very thick layer of blubber (up to 30 cm), no dorsal fin, and a complex circulationcirculatory system (with numerous vascular retes) for conservingadaptations) to conserve heat. Moreover, their highly elevated blow-holesblowholes are thought to be an adaptation tofor breathing inwithin the cracks in sea ice.
Narwhal inhabit the North Atlantic Ocean sector on both sides of Greenland and the archipelagos of, as well as Svalbard and Frans Josef Land archipelagos. They also occupy some waters north of Canada and Russia; they are very rare in the Pacific Arctic. Similar to their close relative, the white whale, these mid-sized odontocetes liveremain in social group (pods) throughout their lives, often in association with sea ice. They are deep divers that feed on arcticArctic cod, polar cod,
Ringed seals occur throughout the Arctic. They are the only northern seal that can maintain breathing holes in thick sea ice and thus are distributed well beyond the range of the other northern true seals – north to the Pole (Heide-Jørgensen and Lydersen, 1998; Gorbunov and Belikov, 2008). They are extremely dependent on sea ice, which is their exclusive breeding and haul-out platform. Typically, they prefer land-fast ice in fjords and along coastlines, with reasonably thick
Polar bears have a circumpolar Arctic distribution, which includes the entire northern Barents Sea south to Novaya Zemlya. They are heavily dependent on sea ice for foraging and for travelling to and from terrestrial denning areas; they depend on thick layers of snow in maternity denning areas. They prefer first-year ice that develops over shelf seas for hunting, where ice-associated seals (their primary prey) are most abundant (Derocher et al., 2002).
Walruses are distributed across the circumpolar Arctic, but their distribution is discontinuous and two subspecies are recognized: one in the Pacific; and the other in the Atlantic. In the northern Barents Sea, they are found from Svalbard through to Franz Josef Land; in the southern Barents Region, they occur in the Pechora Sea and the Kara Sea. Recently, they have been observed regularly in the White Sea as well (Klepikovsky and Lisovsky, 2005; Svetochev and
All Arctic endemic marine mammals in the Barents Sea (polar bear, walrus, ringed seal, bearded seal, harp seal and hooded seal, white whale, narwhal and bowhead whale) are associated with sea ice throughout much or all of their annual cycle. Hence, they are all currently a conservation concern (e.g. Tynan and DeMaster, 1997; Stirling et al., 1999; Kovacs, 2004; Derocher, 2005; Belikov, 2008; Wiig et al., 2008; Kovacs and Lydersen, 2005, 2008; Kovacs et al. 2011a, 2012) because of the declines in Arctic ice coverage over recent decades, that have been particularly acute in the Barents Region (see Laidre et al., 2015).
Numbers of seabirds breeding in the Barents Sea Region have changed dramatically over the last 50 years. A recent assessment of population status and trends has been conducted, based on monitoring and census date for several species breeding in the western part of the Barents Sea (i.e., Norwegian mainland and Svalbard) (Fauchald et al., 2015). Resulting analyses indicate that breeding populations of subarctic pelagic auk species (common guillemot Uria aalge, razorbill
Future higher temperatures in the Norwegian Arctic, including the Barents Sea, will likely cause several pathogens (parasites, bacteria, viruses) to extend their distributions northward (Tryland et al., 2009). The prevalence and abundance of pathogens may also change. Such a change in distribution of pathogens may have several consequences for both wild and domesticated animals, which are difficult to predict due to a lack of data.
Several seabird populations in the Barents Sea region are of international importance. The most numerous species are: Brünnich´s guillemot (Uria lomvia); little auk (Alle alle); Atlantic puffin (Fratercula arctica); black-legged kittiwake (Rissa tridactyla), northern fulmar (Fulmarus glacialis); and common eider (Somateria mollissima). An important part of the global breeding population of the rare ivory gull (Pagophila eburnea) is found within the northern part of the region — in Svalbard and Franz Josef Land.
The Barents Sea is inhabited by 21 species of sea mammals. Among these, 11 species are threatened according to the IUCN Red List, 13 are included in the Red Book of the Russian Federation (2001) and 8 extant species are on the endangered species list of Norway (Table 4.3.6) (plus the recently extinct northern right whale stock). Anthropogenic factors thought to be most harmful for marine mammals are fisheries interactions, pollution, and climate warming; the
The Barents Sea region is inhabited by 28 fish species which are either on the Global Red List (8 species) or on the Norwegian Red List (25 species) (Table 4.3.6). Among these, 13 are data deficient (DD) species, i.e. the species would likely appear on the red list if adequate information were available. When considering the lists of rare and threatened marine fish species, 3 main groups of impact factors may be considered: 1) fisheries (catch and by-catch); 2) environmental
In recent decades, non-indigenous species which may be considered both “introduced” and “invasive” have appeared in the Barents Sea. Currently, 15 of them have been identified. These organisms entered the Barents Sea either in a natural manner — through the expansion of habitat due to global warming — or as a result of human activities, related to the intentional or accidental introduction of non-indigenous species.