Human activities and its effects in the Barents Sea
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). Current knowledge of the response of benthic communities to the impact of trawling is still rudimentary. The benthos data from the ecosystem survey in 2011 has been used to assess the vulnerability of benthic species to trawling, based on the risk of being caught or damaged by a bottom trawl (WGIBAR report 2016).
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 substratum, depth, gear, and type of organism. Seabed characteristics from the Barents Sea are only scarcely known 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.
The impact of fisheries on the ecosystem is summarized in the chapter on Ecosystem considerations in the AFWG report (ICES 2016c), and some of the points are:
In most of the measured years, the benthos biomass in the northeast part of the Barents Sea (NE) was above the total Barents Sea mean (Figure 4.6.1). But from 2013 and ongoing, the mean biomass (see also black arrows in Figure 3.4.3 lower panel) was reducing, and was record low (<20 kg/n.ml) in 2016, and below the total Barents Sea mean.
During 2013, the NAO index changed from negative values in January–March to slightly positive values which lasted the rest of the year. During winter (2012 –2013) northerly, northwesterly and northeasterly winds prevailed over the Barents Sea; during summer (April–August) southerly, southwesterly, and southeasterly winds prevailed. During autumn (September–October) wind direction shifted to easterly and northeasterly.
Air temperature data from the NOMADS (NOAA Operational Model Archive Distribution System http://nomad2.ncep.noaa.gov) website were averaged over the western (70–76°N, 15–35°E) and eastern (69–77°N, 35–55°E) Barents Sea. During 2012, positive air temperature anomalies prevailed in the Barents Sea, with the largest values (4–7°C) in the eastern part of the sea from January to April (Figure 4.2.2).
Volume flux in the Barents Sea varies within periods of several years, and was significantly lower during 1997–2002 than during 2003–2006 (Figure 4.2.3). During winter 2006, volume flux was at a maximum throuhout 1997-2013; whereas, during fall volume flux was anomalously low. After 2006, volume flux has been relatively low, particularly during spring and summer. During 2013, volume flux was generally larger than the 1997–2013 average.
Throughout 2013, positive surface water temperature anomalies prevailed in the Barents Sea. The largest anomalies (up to 4.0°C) were found in the eastern sea. Compared to 2012, the surface temperatures were much higher (by 1.3–2.7°C) in most of the Barents Sea, especially in its central and southern parts. In August–September 2013, during the joint Norwegian-Russian ecosystem survey, the surface temperatures were the highest since 1951 in about 50% of the surveyed area (ICES AFWG, 2014).
The Fugløya–Bear Island section receives all Atlantic Water entering the Barents Sea from the southwest. Throughout 2013, Atlantic Water temperature was 0.2°C - 0.5°C above the 1977-2014 long-term average (Figure 4.2.10). Similar to temperature, water salinity also was above the 1977-2014 long-term average throughout 2013, with the anomalies ranging between 0.02 and 0.05, and trending downwards throughout the year (Figure 4.2.11).
Meteorological conditions over the Barents Sea during winter 2011/2012, resulted in decreasing sea-ice coverage. From January through July 2012, ice coverage (expressed as a percentage of the sea area) was 17–32% below average and 7–25% lessthan in 2011 (Figure 4.2.11). During February and July 2012, sea-ice coverage was the smallest observed since 1951 for these months. In August and September 2012, there was no ice in the Barents Sea; the ice edge was located much farther
There were no special researchers on marine mammals on board of Norwegian vessels during ecosystem survey. However, the Norwegian observers of seabirds on boards «Eros», «Johan Hjort», and «Helmer Hansen», as far as possible in parallel also did observations of marine mammals.
8 species of marine mammals were observed during the observation period in the research area, reaching a total of 899 individuals.
During the 2016 Barents Sea Ecosystem Survey (BESS) 96 fish species from 33 families were recorded in the both pelagic and bottom catches, some taxa were recorded at genus or family level only (Prokhorova et al., 2017). In the period 2004–2015 a total of 106 species were caught in demersal trawls during the BESS (Johannesen et al., 2017).
Most of the fish in the Barents Sea are demersal (Dolgov et al., 2011). The demersal fish community consists of about 70–90 regularly occurring species. These have been classified into zoogeographical groups. About 25% are Arctic or mainly Arctic species. The commercial species are all boreal or mainly boreal (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 on plankton and prey of other predators and therefore an important element in the transfer of energy between trophic levels in the ecosystem. The total biomass of 0-group (cod, haddock, herring, capelin, polar cod, and redfish), was 1.95 million tonnes in August-September 2016, which is slightly above the long-term mean of 1.76 million tonnes (Figure 3.5.1). The biomass was dominated by capelin and herring. Most of the biomass was distributed in the central and northern-central part of the Barents Sea.
Benthos is one of the main components of the marine ecosystems. It can be stable in time, characterizing the local situation, and is able to show the ecosystem dynamics in retrospective. 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 mesozooplankton plays a key role in the Barents Sea Ecosystem by channelling food from primary producers to animals higher in the foodweb.
The main features of the distribution patterns show similarities across years, although some be-tween-year variability is apparent.
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).