Scientific report from the Norwegian and Russian Barents Sea ecosystem surveys in August-October 2024 (BESS)

The aim of the Barents Sea ecosystem survey (BESS) in August-October is to monitor the status and changes of in the Barents Sea ecosystem. The survey has since 2004 been conducted annually, as collaboration between the IMR in Norway and the Polar Branch of VNIRO (PINRO) in Russia. The general survey plan, tasks, and sailings routes are usually agreed at the annual PINRO-IMR Scientist Meeting in March, but in 2024, due to external factors making physical meetings between Norwegian and Russian researchers difficult, they were agreed by correspondence. The 21th BESS was carried out during the period from 17-th August to 12th October 2024. by the Norwegian research vessels (“Kronprins Haakon”, “G.O. Sars” and “Johan Hjort”) and the Russian vessels (“Vilnyus”). The scientists and technicians taking part in the survey onboard the research vessels are listed in Table 1. As always, we would like to express our sincere gratitude to all the crew and scientific personnel onboard research vessels for their dedicated work. We also will express our sincere gratitude to all the people involved in planning and reporting of BESS 2024. This is the first part of the survey report summarising status for the environment and the living Barents Sea based on the survey data. The information obtained in BESS 2024 will be further used for the assessment of fish and invertebrate stocks, the evaluation of changes in environmental conditions and biota, and the implementation of various international and national projects.

Figures by: S. Karlson and E. Bagøien

BESS aims to cover the entire ice-free area of the Barents Sea and, from   south to north. The ecosystem stations are distributed on a regular 35×35 nautical mile regular grid except for the slope around Svalbard/Spitsbergen, with additional bottom trawl hauls for demersal fish indices estimation and additional acoustic transects east for Svalbard/Spitsbergen for the capelin stock size estimation. The planned vessel tracks for BESS 2024 are given in fig. 2.1.
BESS 2024 was largely implemented according to the plan. The realized tracks of the research vessels with the sampling taken are shown in Figs. 2.2 and 2.3. The execution of BESS 2024 did not reveal any major changes or irregularities. A relatively large part of the Russian EEZ to the west of the Novaya Zemlya was closed for fishing at the request of the Russian Ministry of Defence, so survey area along the archipelago coast was not fully covered (Fig. 2.2). The restricted navigation area along Novaya Zemlya leads to a gap in information on fish and invertebrates, primarily cod, polar cod and snow crab. The Norwegian vessel 'Johan Hjort' suffered technical problems and had to end the cruise a week early. In order to cover the capelin area, “Kronprins Haakon” changed plans and went into the capelin area, working northwards and then covering the north and west of Svalbard/Spitsbergen. Due to fishing restrictions on the Russian shelf, some of the coverage of Loophole has been shared between Russian and Norwegian vessels. Bad weather throughout the survey slowed down the progress of the survey. The Russian vessel was given five extra vessel-days compared to original plan. However, a strong and lasting storm in the end of September prevented the survey and the north and north-eastern parts of the sea was not surveyed as in previous years (Figs. 2.2 and 2.3). Still, BESS 2024 was largely conducted according to the planned coverage, except small area west of Svalbard/Spitsbergen and west of Novaya Zemlya. The planned schedule for BESS 2024 was 149 days (99NOR+55RUS), while the effective vessel days (time be-tween first and last sample in the vessel logs) was 135 days (82NOR+53RUS). The difference between the two is as expected, as vessels need time for sailing to and from the harbor and preparation before sampling and bad weather. The temporal and spatial progression during the survey was good (Fig. 2.4). Note that in reports from earlier years, only the planned schedule is reported.
The ecosystem survey in 2024 was similar to previous years, covering most ecosystem components. In addition, the standard oceanographic sections "Vardø-Nord" and "Hinlopen" with lower effort (due to weather conditions and technical problems) were taken by the Norwegian vessels and the “Kola” (twice) and Kanin sections were taken by the Russian vessel (Fig. 2.3). During the BESS, in total 320 pelagic hauls, 317 demersal hauls, 393 CDT and 393 plankton nets were taken.

2.1  Sampling methods

In 2024, compared to 2023, there were no changes in sampling gear. Manta trawl was included as standard equipment for monitoring microplastics at BESS in 2022 and was also used in 2024. Fifty samples were collected on Russian vessel and 34 on board Norwegian vessels. A new length stratified individual sampling of haddock was introduced in 2022, increasing samples from one to two fish taken per 5 cm group. This was continued in 2024. 
Plankton stations were carried out within the entire survey water area with sampling in the bottom-0 m layer. On the Kola hydrological section, plankton sampling collected separate for the layers: bottom-0 m, 100-0 m and 50-0 m.
The survey sampling manuals can be obtained by contacting the survey coordinators.
These manuals include methodological and technical descriptions of equipment, the trawling and capture procedures by the sampling tools, sampling and registration of the catch in the lab, and the methods that are used for calculating the abundance and biomass of the biota.

2.2.1 Special investigations

BESS is a useful platform for conducting additional studies in the Barents Sea. These studies can be testing of new methodology, sampling of data additional to the standard monitoring, or sampling of other types of data. It is imperative that the special investigations do not influence the   standard monitoring activities at the survey. The special investigations vary from year to year, and below is a list of special investigation conducted on Russian and Norwegian vessels at BESS 2024, with contact persons. This chapter also briefly mentions some investigations that are typical during survey but not described in the main text of the BESS Report.

                     2.2.1.1 Annual monitoring of pollution levels

In 2024 PINRO continued the annual monitoring of pollution levels in the Barents Sea in accordance with a national program. Samples of seawater, sediments, fish and invertebrates was collected and analysed for persistent organic pollutants (POPs, e.g. PCBs, DDTs, HCHs, HCB) and heavy metals (e.g. lead, cadmium, mercury) and arsenic. The samples were collected at RV "Vilnyus" during BESS in different parts of the Barents Sea. The results from chemical analyses are available in the annual PINRO report “Status of biological resources…”. 

Contact: Andrey Zhilin, PINRO (zhilin@pinro.vniro.ru)

                     2.2.1.2 Collection of samples for biochemical studies

Frozen samples of commercial and non-commercial fish and invertebrates were collected for biochemical studies (ratio of body parts, chemical composition of nutrients, molecular weight of muscle proteins, amino acids and lipid fractions composition) in accordance with a research program. Samples were frozen at a temperature  -18°C immediately after catching before rigor mortis.

Contact: Kira Rysakova, PINRO (rysakova@pinro.vniro.ru)

                       2.2.1.3 Fish pathology research

PINRO undertakes yearly investigations of fish diseases in the Barents Sea (mainly in REEZ). Seven commercially important fish species (total 10 thousand ind.) were studied. Red king crabs (83 ind.) and snow crabs (total 197 ind.)  were examined also for define  “shell disease of crustaceans”. The main purpose of the pathology research is annual estimation of epizootic state of commercial fish and crabs species. The observations are entered into a database on pathology. This investigation was started by PINRO in 1999. Results are available in the annual PINRO report “Status of biological resources…”

Contact: Irina Mukhina, PINRO (imukhina@pinro.vniro.ru)

                     2.2.1.4 Parasitological study

In 2023, observations of the infestation of commercial fish species with helminths that are hazardous to human health continued on board the RV Vilnyus. Cod, haddock, polar cod, capelin, Atlantic herring place and LRD were examined in order to identify hazardous parasites. The results will be published later in PINRO annual report. Moreover, parasite larvae Pseudoterranova sp. from different areas of the Barents Sea were collected and fixed for further genetic studies.

Contact: Irina Mukhina, PINRO (imukhina@pinro.vniro.ru)

                     2.2.1.5 Plankton and fish calorie content investigation

In August and October, hydrochemical observations were made onboard RV “Vilnyus” in the Kola section. Dissolved oxygen in the surface and bottom layers as well as biochemical oxygen demand during 5 days in the bottom layer were measured.

Contact: Igor Manushyn, PINRO (manushyn@pinro.vniro.ru)

                     2.2.1.6 Hydrochemical observations

In August and October, hydrochemical observations were made onboard RV “Vilnyus” in the Kola section. Dissolved oxygen in the surface and bottom layers as well as biochemical oxygen demand during 5 days in the bottom layer were measured.

Contact: Alexander Trofimov, PINRO (trofimov@pinro.vniro.ru)

                   2.2.1.7  Fish diet study

Since 2004, investigations of diet of most abundant pelagic and demersal fish have been conducted annually during the BESS. In 2024 survey, onboard of  Russian vessels stom-achs of polar cod (225), capelin (125), Atlantic herring (225) cod (269), haddock (152), Greenland halibut (87) and skates (14) were collected and fixed for detail analysis. In addition, 15 kg of small non-commercial fish were frozen whole. Express quantitative analysis onboard RV “Vilnyus” during the cruise include of 3213 stomachs of 16 fish species. Of these, 849 cod stomachs were analyzed. 
Onboard of Norwegian vessels 1020 stomachs of cod were collected and frozen for detailed analysis. In addition, samples were collected and frozen for capelin, polar cod and Atlantic herring.

Contact: Andrey Dolgov, PINRO (dolgov@pinro.vniro.ru), Irina Prokopchuk, PINRO (irene_pr@pinro.vniro.ru), Bjarte Bogstad, IMR (bjarte.bogstad@hi.no)

3.1 Data Bases

A wide variety of data are collected during the ecosystem surveys. All data collected during the BESS are quality controlled and verified by experts: oceanography by Randi B. Ingvaldsen (IMR) and Aleksandr Trofimov (PINRO) fish catch data by Herdis Langøy Mørk (IMR) and Tatyana Prokhorova (PINRO) during and after the survey; plankton data by Jon Rønning and Espen Bagøien (IMR) and Irina Prokopchuk (PINRO); benthos data by Anne Kari Sveistrup (IMR) and Nataliya Strelkova (PINRO); and marine mammals data by Frederike Boehm (IMR) and Roman Klepikovskiy (PINRO). The  data are stored in IMR and PINRO national databases, with different formats. However, the data is exchanged so that both sides have access to each other’s data and use equal joint data. 

3.2 Data Application

The BESS aimed to cover the whole Barents Sea ecosystem geographically and provide survey data for commercial fish and shellfish stock estimation. Stock estimation is particularly important for capelin, because capelin TAC is based on the survey result, and the Norwegian-Russian Fishery Commission determines TAC immediately after the survey. In addition, a broad spectrum of physical variables, ecosystem components and pollution are monitored and reported. The survey data will be used by each party for various purposes within the framework of national and international programs.

This survey report is based on joint data and contains the main results of the monitoring. The survey report will be published in the IMR/PINRO Joint Report series. Missing chapters will be published in the 2025 BESS survey report.

From 2026, the BESS report will be published in a report series named  «IMR/Polar Branch of VINRO Joint Report Series».

All reports from BESS from 2004 until the latest are available at this web site: https://imr.brage.unit.no/imr-xmlui/handle/11250/2658167.

4.1 Hydrography

The report on marine environment Ch. 4.1  will be included in the survey report for the 2025 BESS.

4.2  Anthropogenic pollution

4.2.1  Marine litter

Figures by: D. Prozorkevich

Surface observations of litter were carried out along the known-length transects of with marine mammal observations from Norwegian and Russian vessels.

Plastic was the most frequent material type of floating litter observations (69.0 % of observations) (Fig. 4.2.1.1). The maximum surface observation of plastic litter was 0.30 m3 per nm (a roll of rope from a crab trap). The average surface observation of plastic was 0.007 m3 per nm. Fishery related litter was recorded in 46.9 % of plastic litter observations at the surface (Fig. 4.2.1.2). Fishery related plastic was represented by ropes, pieces of nets and floats/buoys. Fishery plastic maximum and average volume was 0.30 m3 per nm and 0.014 m3 per nm, respectively, and it is larger than non-fishery plastic (maximum and average observations of 0.001 m3 per nm and 0.0001 m3/ per nm, respectively).

Treated wood (wooden sticks, pallets and logs) was recorded in 23.9 % of the surface litter observations. The maximum observation of wood was 0.08 m3 per nm, with the average of 0.015 m3 per nm. It should be noted that wood is the natural type of litter and biodegrades naturally in the environment.

Metal, paper and rubber were observed singularly (1.4-4.2 % of the observations).

Observations of litter in the trawl stations were done during the survey. Onboard the Norwegian vessels litter from trawls were recorded according to the international manual for seafloor litter data collection and reporting from demersal trawl samples. Onboard the Russian vessels a detailed description of the litter was carried out, which then made it possible to classify.

Anthropogenic litter was observed in 11.3 % of pelagic trawl stations (Fig. 4.2.1.3). Plastic usually is the most frequent material type observed in pelagic trawls and constituted 97.2 % of the observations (it was recorded in 11.0 % of all pelagic trawls). Weight of plastic litter from pelagic trawls varied from 0.00004 kg per nm to 0.149 kg per nm, with an average of 0.007 kg per nm. Fishery related litter (such as ropes made from synthetic fibres and pieces of fishing net) constituted 54.3 % of litter registrations from pelagic trawls (Fig. 4.2.1.4).

Other types of litter in pelagic trawls are textile (observed in 1.3 % of pelagic trawl stations and constituted 11.1 % of the litter observations) and unrecognisable items and items that do not fit in other categories («other»), which was registered only in one pelagic station. Weight of textile varied from 0.001 kg per nm to 0.003 kg per nm. It should be noted that textile is a natural product, e.g. ropes made from natural fibres (such as cotton, sisal, hemp, or coir) or all types of clothing (textile and woven products).

From the bottom trawls, 24.2 % of the stations contained litter (Fig. 4.2.1.5). Plastic was the most frequently observed material in the bottom trawls as in the pelagic (89.0 % of stations with observed litter and 21.5 % of the bottom trawls). Weight of plastic litter in bottom trawls varied from 0.0001 kg per nm to 1.248 kg per nm, with an average of 0.04 kg per nm. Fishery related litter constituted 64.6 % of registrations from bottom trawls (Fig. 4.2.1.6).

Wood (processed objects made of wood, e.g. logs, or planks) and textile belong to categories of natural product. Wood was observed in 2.6 % of bottom trawl stations (in 11.0 % bottom trawls with litter registrations). Weight of wood in bottom trawls varied from 0.006 kg per nm to 0.786 kg per nm, with an average of 0.28 kg per nm. Textile was registered in 3.6 % of bottom trawl stations (in 15.1 % bottom trawls with litter). Weight of wood in bottom trawls was 0.001-0.115 kg per nm, with an average of 0.02 kg per nm.

Other material types of litter (metal, glass or unrecognisable items) were observed in bottom trawls singularly (2.7-5.5 % of the bottom trawl stations with observed litter).

5.1 Phytoplankton

Text and figures by: Sarah Lerch

Samples used to characterize phytoplankton community composition and abundance were collected from a total of 88 stations over the course of three separate cruises. Samples were collected from Hinlopen and Vardø-Nord Extended during the BESS between August and October. In this report we also present results that were obtained on other cruises (Fugløya-Bjørnøya section in June and September) but are relevant for research at BESS. Microscopy was used to identify and quantify taxa in 30 preselected stations along the section, covering multiple Barents sea sub-regions (Fig. 5.1.1). Algae-net and metabarcoding samples were also collected which can be used to qualitatively assess community composition. In total, 18 Algae-net and 55 metabarcoding samples were collected.

Samples for algal cell counts (100 ml) were taken from 10 m CTD collected water and fixed in Neutral Lugol. Microscope counts were performed following the Utermöhl (1958) method on CTD samples to quantify abundance and community composition at the IMR Flødevigen Plankton Laboratory. Qualitative Algae-net samples were collected using a vertical net tow (10 μm mesh; 0.1 m² opening; 30-0 m), fixed with 2 ml 20% formalin in a 100 ml bottle and stored for future use. Metabarcoding samples were collected by filtering approximately 2 l of seawater, pre-filtered with 180 µm mesh, on to 25 mm filters with a pore size of 5 µm. Samples were then stored at -80 °C for future DNA extraction and sequencing.

Microscopy algal counts include heterotrophic and autotrophic groups, these communities will therefore be referred to as microplankton in the summarized results below.

5.1.1  Results 

Based on microscopy counts, the average concentration of Barents Sea microplankton in the late summer/ early fall (August-October) was 3.89×105 ± 5.68×10⁵ cells l^-1. The average community was numerically dominated by flagellates (55%, 2.16×10⁵ ± 5.91×105 cells l^-1), cryptophytes (14%, 5.48×10⁴ ± 4.27×10⁴ cells l^-1), and haptophytes (9%, 3.51×10⁴ ± 9.03×10⁴ cells l^-1).

Microplankton abundances and communities varied spatially across the Barents Sea in the late summer/ early fall (Figure 5.1.2). Cell concentrations varied by two orders of magnitude between stations with a minimum concentration of 2.76×10⁴ cells l^-1 and maximum of 2.89×10⁶ cells l^-1. Higher concentration stations were generally found on the southern section of the Vardø-N Extended transect. The community at the highest concentration station was almost completely comprised of flagellates, other stations showed a more diverse mixture of flagellates with cryptophytes and in some cases haptophytes.

Within these data diatoms are the only purely photosynthetic group described at a high taxonomic level. During the late summer/ early fall diatom abundance was relatively low, with the most abundant stations found in the south (Figure 5.1.3). Pseudo-nitzschia  section. Leptocylindrus danicus, Proboscia alata, and Cylindrotheca were numerically important at some of the higher abundance stations within the Vardø-Nord section.

The combination of June and September sampling along the Fugløya-Bjørnøya transect allows us to describe seasonal differences in microplankton cell concentrations and community composition.  Average cell concentrations measured were the same order of magnitude in June (6.25×10⁵ ± 5.54×10⁵ cells l^-1) and September (2.28×10⁵ ± 1.15×10⁵ cells l^-1), although June samples were characterized by greater intra-station variability with particularly high cell concentrations at fixed stations 11 and 16 in June (Figure 5.1.4). At the broad taxonomic group level, the June Fugløya-Bjørnøya section communities were less diverse than September communities, with three stations numerically dominated by either diatoms or haptophytes (Figure 5.1.4). Diatom communities had no overlapping, abundant (> 15%), taxa between June and September (Figure 5.1.5). Chaetoceros, Corethron hystrix, and Thalassiosira were found exclusively in the June samples. In contrast, Cylindrotheca, Pseudo-nitzschia, Proboscia alata, and Guinardia delicatula were found exclusively in September.  

5.2. Mesozoplankton biomass and geographic distribution

Text by: Espen Bagøien and Irina Prokopchuk

Figures by: Espen Bagøien

5.2.1 Data collection

Mesozooplankton sampling stations during the BESS in 2024 are shown in Fig. 5.2.1. In the Norwegian sector the WP2 net (opening area ~ 0.25 m²) was applied, while in the Russian sector the Juday net (opening area ~ 0.11 m2) was used. Both gears were rigged with nets of mesh-size 180 μm and hauled vertically from near the bottom to the surface. The WP2 and Juday nets provide roughly comparable results with respect to mesozooplankton biomass and species composition (Skjoldal et al., 2019). The Norwegian biomass samples are dried before weighing, while the Russian samples are preserved in 4% formalin and their wet weight determined. Dry-weight is then estimated by dividing the wet-weight with a factor of 5.

The time-periods for sampling in the Russian and Norwegian sectors were similar this year (Fig. 2.4).

The spatial distribution of total mesozooplankton biomass shown in Fig. 5.2.1 is based on a total of 293 stations, of which 161 were located in the Norwegian sector and 132 in the Russian sector. Within the Norwegian sector, the average biomass was 6.2 (± 4.8 SD) g dry-weight m^-2. The average zooplankton biomass for the samples within the Russian sector was 7.5 (± 4.5 SD) g dry-weight m^-2. All stations shown in Fig. 5.2.1 are included in the 2024 biomass averages here presented. Note that 10 stations in the central Barents Sea were sampled both by IMR and PINRO (not shown). In these specific cases the IMR data were excluded from Fig. 5.2.1 as well as the calculations of biomass given above.

Comparison of average biomasses across years is vulnerable to differing area coverages. Challenges in covering the same area over a series of years are inherent in such large-scale monitoring programs, and interannual variation in ice-cover and logistical issues are two of several reasons for this. To improve the regularity of the sampling grid across the survey area in 2024, stations belonging to the Hinlopen-section north of Svalbard/Spitsbergen as well as the Vardø-North section were omitted when calculating average biomass (excluded from Fig. 5.2.1). Differences in spatial coverage among years, as well as spatial variability in station density within the survey region will impact biomass estimates, and particularly so in an environment characterized by large-scale patterns in biomass distribution. Hence, the average biomasses for the Norwegian and Russian sectors as presented here are not directly comparable with those from other years.

Such challenges fall outside the scope of this cruise report, but are addressed in other fora, for instance by analysing time-series within spatially consistent sub-areas.

The overall distribution patterns show similarities across years, although some interannual variability is apparent. In 2024 we observed the familiar pattern of comparatively high biomasses in the southwestern region, and north and north-east of Svalbard/Spitsbergen, as well as the deeper parts of the southeastern region. The biomasses were relatively low in the central regions including the bank areas, and very low in the southeastern corner of the Barents Sea (Fig. 5.1.1).

Several factors may impact the levels of zooplankton biomass in the Barents Sea;

• Advective supply of zooplankton from the Norwegian Sea
• Local zooplankton production rates – which are linked to temperature, nutrient conditions and primary production rates
• Predation from carnivorous zooplankters (jellyfish, krill, hyperiids, chaetognaths, etc.)
• Predation from planktivorous fish including capelin, young herring, polar cod, juveniles of cod, saithe, haddock, and redfish
• Predation from marine mammals and seabirds

The release of this chapter is postponed to the 2025 BESS report due to the ongoing process of transferring the index estimations to the StoX platform

This chapter has been pre-released as "Skaret & Prozorkevich 2025 Commercial pelagic fish - Pre-released contribution to the scientific report from the Norwegian and Russian Barents Sea ecosystem surveys in August-October 2024 (BESS). IMR/PINRO Joint Report Series 2025/2, 26 pp."

7.1    Capelin (Mallotus villosus)

The coverage of the capelin distribution was synoptic with very high effort allocated to the important bank areas. The capelin coverage was considered to be close to complete for 2024 (see Figure 7.1.1.1), even though the south-western part of the shelf west of Svalbard/Spitsbergen was not covered. This west shelf is normally not an area with important amounts of capelin. A summary of the capelin stock assessment for 2024 is given in Barents Sea capelin advice sheet 2024 with more details provided in Barents Sea capelin assessment report 2024.

7.1.1   Geographical distribution

The geographical distribution of capelin recorded acoustically is shown in Figure 7.1.1.1. The capelin was distributed quite far north, but not as far north as last year when the population size was much higher. The main distribution area was the Great Bank which is the normal core area at this time of the year. Some recordings were also made north of Svalbard/Spitsbergen which was also observed last year.

7.1.2   Abundance by size and age

A detailed summary of the acoustic stock estimate is given in tab. 7.1.2.1, and the time series of abundance estimates is summarized in tab. 7.1.2.2. A comparison between the estimates in 2024 and 2023 is given in tab. 7.1.2.3 with the 2023 estimate shown on a shaded background.

The total stock in the covered area was estimated to about 887 thousand t, which is only about a third of the long-term average level (2.79 million t). About 60 % (534 thousand t) of the 2024 stock had length above 14 cm and was therefore considered to be maturing. In terms of biomass, the contribution to the total was quite equal for 1, 2, 3 and 4 year-olds (tab. 7.1.2.1). The abundance of 1 and 3 year-olds was less than a third of the long term average and 2-year-olds less than a sixth of the long term average. Only the abundance of 4 year-olds (2020-yearclass) and 5 year-olds (2019-yearclass) were stronger than the long-term average.

Average weight at age increased compared to last year for the age groups 2-4. For 3 and 4 year-olds it was still well below the long term average, whereas it was above the long term average for 1 and 2-year-olds (fig. 7.1.2.1 and tab. 7.1.2.2).

Estimates based on Target strength (TS) Length (L) relationship : TS= 19.1 log (L) – 74.0

Note:«+» <0.005*million t

7.2     Polar cod (Boreogadus saida)

7.2.1  Geographical distribution

The acoustic recordings of polar cod are shown in fig. 7.2.1.1. There were no areas with really high concentrations of polar cod, but the concentrations adjacent to the Great Bank dominated. Only small concentrations of polar cod were found to the south near the Kara Strait where huge concentrations were found in 2023. There were significant recordings of polar cod along the north-easternmost of transects which indicate that parts of the polar cod stock were distributed east and possibly north of the covered area.

7.2.2. Abundance estimation

The stock abundance estimates of polar cod by age, number and weight in 2024 is given in tab. 7 .2. 2 .1 and the time series of abundance estimates is summarized in tab. 7 .2. 2 .2. The estimated means are from 500 bootstrap replicas made in StoX 4.1.1.

The total estimated abundance of polar cod in 2024 was low, less than 15% of the estimate from 2023. Age group 1 dominated the abundance while age group 2 dominated biomass, but the abundance of all age groups was well below the levels in 2023.

The north-east part of the Barents Sea where polar cod is often distributed has not been covered since 2020. There are also indications of a northwards distribution change in polar cod, so the survey results must be interpreted with caution. However, the estimates indicate that there has been a very strong dynamic in the Barents Sea polar cod stock abundance during the past decade, especially compared to the period 1991-2013.

Estimates based on Target strength (TS) Length (L) relationship : TS= 21.8 log (L) – 72.7

* numbers partly based on VPA estimates 

** incomplete survey coverage

7.3   Herring (Clupea harengus)

7.3.1  Geographical distribution

Young Norwegian spring spawning herring (NSSH) was distributed over large parts of the southern Barents Sea (Figure 7.3.1.1).

7.3.2  Abundance estimation

The estimated total number and biomass of NSSH in the Barents Sea in the autumn 2024 is shown in tab. 7.3.2.1, and the time series of abundance estimates is summarized in tab. 7 .3. 2 .2. Total numbers in 2024 were estimated at ca. 72 billion individuals (tab. 7.3.2.1). This is the third highest on record and ca. 2.5 times higher than the long-term average (tab. 7.3.2.2). Abundance of age group 1 was low, while abundance of age group 2 (2022 year class) was >5 times higher than the long-term average and abundance of age group 3 (2021 year class) was >6 times higher. The abundances of both 2 and 3-year-olds were the highest on record. Also abundance of age group 4+ was above the long-term average. The very high abundances of 2 and 3-year-olds were expected given the very high abundances of 1 and 2-year-olds in 2023. The total biomass of NSS-herring in the Barents Sea, which is dominated by biomass of 2 and 3-year-olds is the highest that has been measured since 1999. 

Estimates based on Target strength (TS) Length (L) relationship: TS= 20.0 log (L) – 71.9

*in mix with Kanin herring in the south-eastern part of the coverage area

**survey coverage only on Norwegian (western) side

7.4   Blue whiting (Micromesistius poutassou)

7.4.1  Geographical distribution

Blue whiting contributes to make up the mid-trophic pelagic component in the south-western part of the Barents Sea ecosystem. The Barents Sea is on the border of the distribution area for the blue whiting, but with incoming strong year-classes, increased abundance of young blue whiting in the Barents Sea is normally observed. The distribution of blue whiting from the BESS 2024 is shown in fig. 7.4.1.1. The distribution was similar to last year following the shelf edge north to Svalbard/Spitsbergen and with some recordings stretching north of Svalbard/Spitsbergen.

7.4.2  Abundance by size and age

The estimated total number and biomass of blue whiting in the Barents Sea in the autumn 2024 is shown in tab. 7.4.2.1, and the time series of abundance estimates is summarized in tab. 7 .4. 2 .2.

The total abundance and biomass are higher than last year but below the long-term average (tab. 7.4.2.2). The 3 and 4-year-olds (2021 and 2020 year classes) dominate both the abundance and biomass (tab. 7.4.2.1).

Estimates based on Target strength (TS) Length (L) relationship: TS= 20 log (L) - 65.2

Estimates based on Target strength (TS) Length (L) relationship : TS = 20 log (L) - 65.2 (Recalculation by Åge Høines, IMR 2017)

Note:«+» <0.5

Maps by: IMR, Demersal fish section

Indices calculated from the ecosystem survey bottom trawl data (not shown here) are used in annual assessments of cod, haddock, beaked redfish and Greenland halibut. Data from the ecosystem survey is currently evaluated as part of the process of establishing an assessment model for the wolffish species. The maps shown are based on bottom trawl catches. For cod and haddock, we provide swept area estimates as numbers per nm², with length dependent sweep width corrections.  The parameters for the length dependent sweep width correction are given in tab. 8.1.

The maps for cod and haddock are provided for four length groups: > 20 cm, 20-34 cm, 35-49 cm and ≥50cm. 

The maps showing the distribution of the other species are given as total catch in kg per nm.

Note that projections of the maps in chapter 8 in the current report differ from maps previous years.

8.1    Cod (Gadus morhua) 

At the time of survey cod usually reaches the northern and eastern limits of its feeding area. In general, the cod was distributed over the entire area surveyed except the far northeastern part, with the highest concentrations on the shallower bank areas (figs. 8.1.1-8.1.4) Smaller cod (< 20 cm) was hardly found in the southeastern area, and cod 20-34 cm was not found in the southwestern part.

8.2 Haddock (Melanogrammus aeglefinus)

Haddock was found mainly in shallower areas in the western and south-eastern Barents Sea. Smaller haddock (<20cm, Fig. 8.2a), had a wider distribution than the larger individuals. Haddock < 20 cm are mainly 0-group and 1-group haddock.  Some of these smaller individuals were caught north of Svalbard/Spitsbergen. The larger and older haddock (Figs. 8.2.1-8.2.4) were mainly found in the south-eastern Barents Sea, along the coast of Northern Norway and on the shallower bank areas, and along the bank-edges both north and south of Bear Island Trough and Hopen Trench.

8.3   Greenland halibut (Reinhardtius hippoglossoides)

BESS covers an area where mainly younger Greenland halibut is found, with nursery areas in the northernmost part. In recent years there has been a noticeable increase in the number of fish between 20-40 cm. As in previous years, Greenland halibut was observed in most catches in the deep areas of the Barents Sea (fig. 8.3). The distribution pattern was similar to previous years, with main concentrations observed around Svalbard/Spitsbergen, to the west of Franz Josef Land, and in the Bear Island Trench.

The BESS registrations result in three indices, one for fish up to 17 cm, one for fish between 18 and 27 cm, and one for fish above 28 cm.  Moreover, trawl indices from surveys that cover deeper waters at the continental slope, are also used in the stock assessment.

8.4  Golden redfish (Sebastes norvegicus)

Data from the ecosystem survey is currently not used in the assessment of golden redfish. In 2024, centers of abundance for golden redfish were observed along the coast of the Troms region in Norway, along the Murman coast, and along the northern and western coast of Svalbard/Spitsbergen (fig. 8.4). As in earlier years observations in the eastern Barents Sea, were few and of low abundance.  

8.5   Beaked redfish (Sebastes mentella)

Data from BESS is used in the assessment of beaked redfish. As in previous years, beaked redfish were absent from an area north of Bear Island and in the south-eastern part of the Barents Sea (Fig. 8.5). Moreover, in contrast to last year, the species was largely absent east of 40 °E and along the west shelf of Svalbard (but note lacking coverage there). The highest catches of beaked redfish were concentrated in the area south and east of Bear Island. and some catches were also recorded along the shelf break north of Bear Island and north and northwest of Svalbard/Spitsbergen. Catch weight decreased from the west towards the eastern Barents Sea.

8.6  Long rough dab (Hippoglossoides platessoides)

The long rough dab as usually the most numerous species in the demersal survey in the Barents Sea. Long rough dab was found in almost all trawl catches in the survey area, but the maximum densities and highest catches were in the Central Bank, along the slopes of the Svalbard/Spitsbergen bank and in a small area in the southeast. (fig. 8.6). The numbers and biomass of long rough dab in the Barents Sea have been stable over the past 20 years. Based on the ecosystem survey data, the total stock biomass index of this species is between 400 and 500 thousand tons.

8.7  Plaice (Pleuronectes platessa)

Plaice is mainly found in the southeastern Barents Sea from the coast of Murman to the Kolguev Island. The highest densities were on the border to the White Sea and in the area closed to trawl fishing, where the Kamchatka crab fishing takes place (Fig. 8.7).

The distance between the trawl stations at the ecosystem survey is too large to correctly assess plaice distribution and abundance. The plaice distribution is very patchy, and partly found in areas that cannot be trawled, this greatly affects the possibility to assess the stock. According to the ecosystem survey data, the total stock biomass index is about 50 thousand tons and its biomass has been stable in recent years.

8.8   Atlantic wolffish (Anarhichas lupus)

Atlantic wolffish is the most numerous of the three species of wolffishes inhabiting the Barents Sea, while due to its smaller size has the lowest biomass of the three species. At the survey in 2024 Atlantic wolffish was mainly found in Atlantic waters north-west of Svalbard/Spitsbergen and in shallower waters along the edge of the Hopen Trough and Bear Island Trench and scattered as well as scattered further south (fig. 8.8).

8.9   Spotted wolffish (Anarhichas minor)

In 2024 the spotted wolffish was found in the central part of the sea with densities along the slopes of the Svalbard/Spitsbergen and Central Banks (fig. 8.9).

8.10  Northern wolffish (Anarhichas denticulatus)

In 2024 Northern wolffish was distributed along the slopes of Hopen Trench extending into the slopes of the Central Basin in the eastern Barents Sea (Fig. 8.10).

 9.1  Small non-target fish species

This group will no longer be updated due to reduced resources.

9.2  Fish biodiversity in the demersal compartment

Figures by: D. Prozorkevich

9.2.1 Norway pout (Trisopterus esmarkii).

Norway pout is usually found in the south-western part of the ecosystem survey area. The distribution of Norway pout in 2024 was approximately the same as in 2023 (fig. 9.2.1).

The maximum catch of Norway pout in 2024 (138.7 kg/nm) was a little lower than in 2023 (153.9 kg/nm), but the average catch in 2024 (1.6 kg/nm) was a little higher (1.4 kg/nm in 2023). Total abundance and biomass of Norway pout in 2024 (1520.2 million individuals and 44.1 thousand tons respectively) were higher than in 2023 (1067.8 million individuals and 36.1 thousand t respectively) (tab. 9.2.1).

9.2.2 Norway redfish (Sebastes viviparus).

Norway redfish occurred in the south-western area of the survey along the Norwegian coast in 2024 (fig. 9.2.2).

The maximum catch of Norway redfish in 2024 (63.0 kg/nm) as well as the average catch (0.7 kg/nm) were much lower than in 2023 (330.7 kg/nm and 1.6 kg/nm respectively). Total abundance and biomass of this species in 2024 (127.4 million individuals and 13.6 thousand t) were less than in 2023 (189.6 million individuals and 28.9 thousand t respectively) (tab. 9.2.1).

* – 2022 is not included due to the lack of synoptic coverage

9.2.3 Thorny skate (Amblyraja radiata) and Arctic skate (Amblyraja hyperborea)

Thorny skate and Arctic skate were selected as indicator species to study how ecologically similar fishes from different zoogeographic groups respond to changes of their environment. Thorny skate belongs to the mainly boreal zoogeographic group and is widely distributed in the Barents Sea except the most north-eastern areas, while Arctic skate belongs to the Arctic zoogeographic group and is found in the cold waters of the northern area.

In 2024 thorny skate was distributed over a wide area from the north-western to the south-western and south-eastern Barents Sea where warm Atlantic and Coastal Waters dominated (fig. 9.2.3). Compared to 2023 this species occurred less abundant in the south-eastern area. 

Thorny skate was observed in 31.1 % of the bottom stations in 2024, approximately the same level as in 2023 (32.7 %). Thorny skate was distributed within a depth of 61-493 m, and the highest biomass occurred at depth of 150-299 m (55.9 % of total biomass). The mean catches in 2024 (0.8 individuals per nm and 0.7 kg per nm) were lower than in 2023 (1.1 individuals per nm and 0.9 kg per nm respectively) (tab. 9.2.2). The estimated total abundance and biomass of thorny skate in 2024 (23.2 million individuals and 20.5 thousand t) were also lower than in 2023 (32.3 million individuals and 28.0 thousand t and have not been ​​in 10 years (tab. 9.2.1).

            * – 2018 is not included due to the poor survey coverage

        ** – 2022 is not included due to the lack of synoptic coverage

Arctic skate was only observed in two bottom stations in 2024, at a depth of 336 m in the Central Trough (1 individual: 68 cm and 3.55 kg) and 322 m on the Great Bank (Perseus Bank) (1 individual: 55 cm and 1.85 kg) (Figure 9.2.4). The mean catch (in terms of abundance and biomass) of Arctic skate in 2024 (0.01 individuals per nm and 0.02 kg per nm) was less than in 2023 (0.02 individuals per nm and 0.03 kg per nm) (Table 9.2.3). The total abundance and biomass of Arctic skate in 2024 was not calculated due to lack of sufficient data for analysis.

 * – 2018 was not included due to the poor survey coverage

** – 2022 is not included due to the lack of synoptic coverage

*** – have not been estimated due to lack of sufficient data for analysis

9.3  Uncommon or rare species

Rare or uncommon species are either species that are not caught at the Barents Sea ecosystem survey every year (e.g. megrim Lepidorhombus whiffiagonis – known from the Atlantic coasts off northern Africa to Norway, including the Mediterranean, the British Isles and Iceland, but uncommon in the Arctic region), or caught most years but in low numbers and with limited occurrence (e.g. Arctic rockling Gaidropsarus argentatus, known off southeastern Greenland, off Iceland and the Faroe Islands to the Norwegian coast and northward to the Barents Sea in the survey area found along the continental slope between the Norwegian coast and Svalbard/ Spitsbergen and eastward to Franz Josef Land). Most of these species usually occur in areas adjacent to the Barents Sea and were therefore found mainly along the border of the surveyed area.

Some uncommon species were also observed in the Barents Sea during the ecosystem survey in 2024 (Figure 9.3.1).

9.4  Zoogeographic and taxonomic groups

During the 2024 ecosystem survey, 83 fish species from 27 families were recorded in the catches. Some specimens were only identified to genus or family level, especially from the families Liparidae, where genus Careproctus includes different species which are difficult to identify onboard. The highest number of species belonged to the families Zoarcidae (13.3 % of the total number of species), Gadidae (12.0 %) and Cottidae (9.6 %). The recorded species belonged to 7 zoogeographic groups: widely distributed, south boreal, boreal, mainly boreal, Arctic-boreal, mainly Arctic and Arctic as defined by Andriashev and Chernova (1994). Only bottom trawl data were used, and only non-commercial species were included in the analysis, both demersal (including bentho-pelagic) and pelagic (neritopelagic, epipelagic, bathypelagic) species (Andriashev and Chernova, 1994, Parin, 1968, 1988). Among the analyzed species most belonged to the Arctic (31.0 % of the total number of species), mainly boreal (25.9 %) and boreal (24.1 %) zoogeographic groups.

The median and maximum catches of non-commercial fish from the different zoogeographic groups are shown in tabs. 9.4.1, 9.4.2. Please note that differences in spatial survey coverage within years are not taken into account).

Widely distributed (only ribbon barracudina Arctozenus risso represents this group), south boreal (e.g. silvery pout Gadiculus argenteus, greater forkbeard Phycis blennoides) and boreal (e.g. moustache sculpin Triglops murrayi, fourbeard rockling Enchelyopus cimbrius) species were mostly found in the central, southwestern and western part of the survey area where warm Atlantic and Coastal Waters dominate (fig. 9.4.1). The median catches of ribbon barracudina in 2024 were one third of that in 2023. The median catches of species from the south boreal zoogeographic group in 2024 half of the median catch in 2023, but the second highest since the start of this times series in 2013. The median catches of species from the boreal zoogeographic group in 2024 were double that in 2023, and at the level as 2020-2021 (tab. 9.4.1).

Mainly boreal species (e.g. three-spined stickleback Gasterosteus aculeatus, gracile eelpout Lycodes gracilis) were widely distributed throughout the survey area (fig. 4.2.1). The median and maximum catches of species from the mainly boreal group were little lower in 2024 than in 2023 (tabs. 9.4.1,  9.4.2).

Arctic-boreal species (e.g. Atlantic poacher Leptagonus decagonus, ribbed sculpin Triglops pingelii) were found in the central, northern and south-eastern part of the Barents Sea (fig 9.4.1). The median catches of species from the Arctic-boreal zoogeographic group in 2024 were approximately at the same level as in 2020-2023 (tab. 9.4.1). The maximum catches in 2024 were lower than in 2023 (tab. 9.4.2).

Mainly Arctic (e.g. Atlantic spiny lumpsucker Eumicrotremus spinosus, nebulous snailfish Liparis bathyarcticus) and Arctic (e.g. pale eelpout Lycodes pallidus, leatherfin lumpsucker Eumicrotremus derjugini) species were mainly found in the northern part of the Barents Sea (fig. 9.4.1). Species from these groups mostly occur in areas influenced by cold Arctic Water, Spitsbergen Bank Water and Novaya Zemlya Coastal Water. Median and maximum catches of mainly Arctic species in 2024 were higher than in 2023 (tabs. 9.4.1, 9.4.2). Median and maximum catches of species from the Arctic zoogeographic group in 2024 were the lowest since 2014 (tabs 9.4.1, 9.4.2).

1 – Coverage in the northern Barents Sea was highly restricted

2 – The survey started in the north

3 – 2018 is not included due to the poor coverage of the Russian Zone

4 – 2022 is not included due to the lack of synoptic coverage

1 – Coverage in the northern Barents Sea was highly restricted

2 – The survey started in the north

3 – 2018 are not included due to the poor coverage of the Russian Zone

4 – 2022 is not included due to the lack of synoptic coverage

10.1 Northern shrimp (Pandalus borealis)

Text by: S. Bakanev, F. Zimmermann

Figures by: S. Bakanev

During the survey in 2024, 317 trawl hauls were completed and 214 of them contained Northern shrimp. The biomass of shrimp varied from several grams to 90.7 kg/nm with an average catch of 8.2 kg/nm (tab. 10.1.1).

As in previous years, the densest concentrations of shrimp were registered in the central part of the Barents Sea and around Svalbard/Spitsbergen (fig. 10.1.1). 

Biological analysis of the Northern shrimp was conducted in 2024 by registering carapace length and developmental stage. As in 2023, the bulk of the population of the Barents Sea shrimp was made up of smaller individuals with a carapace length of 12-22 mm (fig.10.1.2). Information on stages and, thus, the proportion of males and females in 2024 was too limited and is therefore not presented.

10.2   Red king crab (Paralithodes camtschaticus)

Text by: S. Bakanev, A.M Hjelset, H.E.H. Danielsen

Figures by: S. Bakanev

During BESS-2024 the red king crab were recorded in 20 of 317 trawl catches. All stations with king crab were in the Russian part of the survey area. Compared to previous years, in 2024 no expansion of red king crab range northward or eastward was observed, compared to previous years (fig. 10.2.1).

Despite the identical coverage of the red king crab area by stations in 2024, compared to 2023, both the number of recordings and the total catch were significantly lower (tab. 10.2.1).

   * reduced coverage of the Red king crab area

The biomass of red king crab catches in 2024 varied from 1.8 to 90.9 kg/nm compared with 2.9 to 157.2 kg/nm in 2023. The mean biomass and standard deviation were 19.76±7.11 kg/nm compared with 42.04±9.23 kg/nm in 2023.

The abundance of crab in 2024 ranged from 1.1 to 25.6 ind./nm given an average crab abundance of 5.1±2.5 ind./nm compared with 1.2 to 58.0 ind./nm given a mean crab abundance of 13.3±3.2 ind./nm in 2023.

The size structure of the observed red king crab in 2024 was represented by a monomodal distribution of males with sizes of crabs with carapace width 150-220 mm. (fig. 10.2.2). No females were found in the catches in 2024.

10.3 Snow crab (Chionoecetes opilio)

Text by: S. Bakanev, A.M. Hjelset, H.E.H Danielsen

Figures by: S. Bakanev

Catch rates of snow crab per station varied from 0.008 to 9.8 kg/nm, with an average 1.3±0.4 kg/nm compared with 0.002 to 13.2 kg/nm with an average 0.9±0.3 kg/nm in 2023 (fig. 10.3.1).

The catch rates in number in 2024 ranged from 1 to 95 ind./nm with an average of 9.0±3.3 ind./nm compared with 1-40 ind./nm and 6.1±1.1 ind./nm in 2023 (fig. 10.3.1).

* Some stations in the Snow crab area were not surveyed in 2018 and 2019

The size distributions of snow crabs caught in 2023 and 2024 were dominated by females within the size range 30-60 mm carapace width. The male size distribution was broader, ranging between carapace width from less than 25 to more than 110 mm (fig. 10.3.2).

10.4. Icelandic scallop (Chlamys islandica)

Text by: D.Y. Blinova, F. Zimmermann, A.M. Hjelset

Figures by: D.Y. Blinova

Within the survey area, the Icelandic scallop is the dominant species. It is not difficult to identify this species, but in some cases other species of related bivalves (Pseudamussium peslutrae, Karnekampia sulcata, Delectopecten vitreus and Palliolum tigerinum) can be mistake identified as the Icelandic scallop. Therefore, caution should be exercised in assessing the distribution and biomass of the Icelandic scallop, which is shown in this chapter. This issue will be investigated later using genetic analysis and the results will be published in the next reports.

Icelandic scallop was recorded at 70 of 294 trawl stations where benthos was examined in 2024. The survey showed a wide distribution of scallops in the Barents Sea. The deepest record in 2024 was at 493 m, but the most abundant catches were recorded in the shallow banks and elevations of the bottom is Spitsbergen Bank (fig. 10.4.1).

 * - survey area was not complete

Figures by: Kudryashova A.

The list of benthic experts onboard Russian and Norwegian RVs is shown in the Background, tab. 1.

In 2024, bycatch records of megabenthos were made from 294 bottom trawl hauls across four R/Vs during the BESS. Megabenthos was processed to nearest possible taxon with abundance and biomass recorded on all four ships. This was done by three benthic experts from “VNIRO”, and by eight experts from IMR.

11.1   Species diversity

A total of 623 invertebrate taxa (432 identified to species level) was recorded in 2024, which is 5 % (9 %) less than in 2023 (tab. 11.1.1).

In 2024, 69.3 % of benthic invertebrate taxa were recorded at species level versus 66.4 % in previous year. G.O. Sars and Johan Hjort part 1 covered areas with highest biodiversity (403 taxa) and more than 65.1 % of the catch was identified to species level. Vilnyus covered the areas with lowest biodiversity (165 taxa) but had more than 84.8 % of the catch identified to species level. (tab. 11.1.2).