Human activities and its effects in the Barents Sea
Several sea birds species have had dramatic population declines and will be vulnerable for additional threats, like oil pollution (Fauchald et el 2019).
With retreating sea ice, new areas in the northern Barents Sea become available for fisheries, including bottom trawlers. Of special interest to WGIBAR is therefore the vulnerability analysis (Jørgensen et al., 2015).
In order to conclude on the total impact of trawling, an extensive mapping of fishing effort and bottom habitat would be necessary. In general, the response of benthic organisms to disturbance differs with substrate, depth, gear, and type of organism (Collie et al. 2000). Seabed characteristics from the Barents Sea are only scarcely known (Klages et al. 2004) and the lack of high-resolution (100 m) maps of benthic habitats and biota is currently the most serious impediment to effective protection of vulnerable habitats from fishing activities (Hall 1999). An assessment of fishing intensity on fine spatial scales is critically important in evaluating the overall impact of fishing gear on different habitats and may be achieved, for example, by satellite tracking of fishing vessels (Jennings et al. 2001). The challenge for management is to determine levels of fishing that are sustainable and not degradable for benthic habitats in the long run.
In most of the measured by BESS years, the biomass in the northeast part of the Barents Sea was above the total Barents Sea mean (Figure 4.6.1), but from 2013 and ongoing, the mean biomass was reducing, and was record low (<20 kg/nm) in 2016, and below the total Barents Sea mean. As one of the reasons of this decrease could be assumed develop of snow crab population and it predation on the benthos (including juvenile stages of the megabenthic animals.
Arctic sea ice likely reached its 2019 minimum extent of 1.60 million square miles (4.15 million square kilometers) on Sept. 18, tied for second lowest summertime extent in the satellite record, according to NASA and the National Snow and Ice Data Center. The Arctic sea ice cap is an expanse of frozen seawater floating on top of the Arctic Ocean and neighboring seas. Every year, it expands and thickens during the fall and winter and grows smaller and thinner during the spring and summer. But in the past decades, increasing temperatures have caused marked decreases in the Arctic sea ice extents in all seasons, with particularly rapid reductions in the minimum end-of-summer ice extent. The shrinking of the Arctic sea ice cover can ultimately affect local ecosystems, global weather patterns, and the circulation of the oceans.
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The air and water temperatures remained higher than average and typical of warm years, close to those in 2017. In autumn, the Atlantic waters (>3°С) covered relatively large area, but it decreased compared to 2017; the Arctic and cold bottom waters (<0°С) still covered rather small areas, the area of the former was close to that in 2017 but the area of the latter increased. Ice coverage was much lower than average and close to that in 2017. There was no ice in the sea from August to October; in December, the ice coverage was the lowest since 1951.
In August–September 2018, the area covered by warm water (above 4, 3 and 1°С at 50, 100 m and near the bottom respectively) was close to that in 2017 at 50 and 100 m, and 12% smaller at the bottom (Fig. 3.1.16). The area covered by cold water (below 0°С) was also close to that in 2017 at 50 m but 7 and 8% larger than in 2017 at 100 m and near the bottom respectively (Fig. 3.1.16). Since 2000, the area covered by cold bottom water was the largest in 2003 and rather small in 2007, 2008, 2012, 2016 and 2017; in 2016, it reached a record low value since 1965.
Sea surface temperature (SST) (http://iridl.ldeo.columbia.edu) averaged over the southwestern (71–74°N, 20–40°E) and southeastern (69–73°N, 42–55°E) Barents Sea showed that positive SST anomalies (relative to the base period of 1982–2010) prevailed in both areas during 2018 (Fig. 3.1.9).
The Fugløya–Bear Island Section covers the inflow of Atlantic and Coastal water masses from the Norwegian Sea to the Barents Sea, while the Kola Section covers the same waters in the southern Barents Sea. Note a difference in the calculation of the temperatures in these sections; in the Fugløya–Bear Island Section the temperature is averaged over the 50–200 m depth layer while in the Kola Section the temperature is averaged from 0 to 200 m depth.
The volume flux into the Barents Sea varies with periods of several years and was significantly lower during 1997–2002 than during 2003–2006 (Fig. 3.1.4). In 2006, the volume flux was at a maximum during winter and very low during fall. After 2006, the inflow has mostly been relatively low. Throughout 2015 and in winter 2016, the inflow was around 1 Sv larger than the long-term average (Fig. 3.1.4). The exception was March 2016, when the volume flux was temporarily smaller than average. The data series presently stops in May 2016, awaiting the processing of measurement data following new instrumentation in the mooring array, thus, no information about the subsequent period is available as of yet.
Ice conditions in the Barents Sea in 2018 developed as in low-ice years. In January and February, the ice coverage (expressed as a percentage of the sea area) was respectively 20 and 17% lower than average (1981–2010) and close to that in 2017 (Fig. 3.1.3).
During the 2018 Barents Sea Ecosystem Survey (BESS) 83 fish species from 28 families were recorded in pelagic and bottom trawl catches, some taxa were recorded at genus or family level only (Prokhorova et al 2019).
Most Barents Sea fish species are demersal (Dolgov et al., 2011); this fish community consists of about 70–90 regularly occurring species which have been classified into zoogeographic groups. Approximately 25% are either Arctic or mainly Arctic species. The commercial species are all boreal or mainly boreal species (Andriashev and Chernova, 1995), except for Greenland halibut (Reinhardtius hippoglossoides) that is classified as either Arcto-boreal (Mecklenburg et al., 2013) or mainly Arctic (Andriashev and Chernova, 1995).
Zero-group fish are important consumers of plankton and are prey for other predators, and, therefore, are important for transfer of energy between trophic levels in the ecosystem. Estimated total biomass of 0-group fish species (cod, haddock, herring, capelin, polar cod, and redfish) varied from a low of 165 thousand tonnes in 2001 to a peak of 3.4 million tonnes in 2004 with a long-term average of 1.7 million tonnes (1993-2017) (Figure 3.5.1). Biomass was dominated by cod and haddock, and mostly distributed in central and northern-central parts of the Barents Sea.
L.L. Jorgensen (IMR), N.A. Strelkova (PINRO)
Benthos is an essential component of the marine ecosystems. It can be stable in time, characterizing the local situation, and is useful to explain ecosystem dynamics in retrospect. It is also dynamic and shows pulses of new species distribution, such as the snow crab and the king crab, and changes in migrating benthic species (predatory and scavenger species such as sea stars, amphipods and snails with or without sea anemones). The changes in community structure and composition reflect natural and anthropogenic factors. There are more than 3000 species of benthic invertebrates registered in the Barents Sea (Sirenko, 2001), but here we only present the megafaunal component of the benthos collected by trawl and registered (species, abundance and biomass) during the Barents Sea Ecosystem Survey (BESS). This includes mainly large bodied animals with long lifespans. This investigation was initiated in 2005 only – a short timeline relative to investigations related to plankton and fish. Accordingly, interpretation of long-term trends for megabenthic data must be pursued with caution.
Mesozooplankton biomass in the Norwegian part of the Barents Sea in 2018 was slightly above the long-term average for the last 20 years. The mesozooplankton biomass in “Atlantic” subareas of the Barents Sea in 2018 were at similar levels as in previous years, and has shown declining trends on the Central Bank and Great Bank subareas since the peak in 1995. Krill biomass has shown an increasing trend during the last decades. Jellyfish biomass in 2017 was at its third highest level since 1980 – but could not be estimated for 2018.
The phytoplankton development in the Barents Sea is typical for a high latitude region with a pronounced maximum in biomass and productivity during spring. During winter and early spring (January-March) both phytoplankton biomass and productivity are quite low. The spring bloom is initiated during mid-April to mid-May and may vary strongly from one year to another. The bloom duration is typically about 3-4 weeks and it is followed by a reduction of phytoplankton biomass mainly due to the exhaustion of nutrients and grazing by zooplankton. Later in the fall when the increasing winds start to mix the upper layer and bring nutrients to the surface, a short autumn bloom can be observed. However, the time development of this general description can vary geographically. The spring bloom in the Atlantic water domain without sea-ice is thermocline-driven, whereas in the Arctic domain with seasonal sea-ice, stability from ice-melt determines the bloom (Skjoldal and Rey 1989, Hunt et al. 2012). Thus, the spring bloom at the ice edge in the Barents Sea can sometimes take place earlier than in the southern regions due to early stratification from ice melting.
Mercury is the single most toxic element for seabirds. Mercury, along with Cadmium and lead, is one of the heavy metals that are of environmental concern as it can be toxic at levels only moderately elevated above natural ambient levels.
The surface sediments, i.e. the predominant sediment type of the upper ~ 50 cm of the seabed, form the uppermost part of a sediment sequence covering the rocks of the Barents Sea. This sediment sequence varying in thickness from a few to several hundred meters and was mainly deposited during the Quaternary (the last 2.6 million years), a time period where glaciations took place repeatedly.
The map service shows the grain size of seabed surface sediments of the Barents Sea. The map has been compiled in cooperation between the Geological Survey of Norway, Trondheim (Aivo Lepland), and OAO "SEVMORGEO", St. Petersburg (Aleksandr Rybalko), in the frame of the Norwegian-Russian Environmental Commission Workplan 2013-2014, OECEAN 5. Existing maps produced by various organizations served as a basis for the compilation.
This biotope map, covering the entire Barents Sea, has been compiled in collaboration between the Geological Survey of Norway, the Norwegian Institute of Marine Research (IMR) and the Russian Polar Research Institute of Marine Fisheries and Oceanography (PINRO) in the frame of the Norwegian-Russian Environmental Commission Workplan for 2011-2013 and 2013-2015.
The protected areas in Northwest Russia are divided into different categories of protection and management. In strict nature reserves (zapovednik) no economic activities are permitted. National parks are designated to nature conservation, research, educational and cultural purposes as well as controlled recreational activities. In national parks there are restrictions to the management of natural resources. Nature parks (prirodnyi park) are the equivalent of the Norwegian
Scientists, managers and commercial fishermen from Northern Norway, Finland and north-west Russia, White Sea area combined their efforts in the Kolarctic salmon project (2011-2013), with the aim of providing a better knowledge-base for the countries salmon management. Within this joint and unique effort bio-specimen were sampled along the North-Norwegian coast and in Russian Barents and White Seas generating the most comprehensive ecological and genetic datasets for Atlantic salmon (Salmo salar).