Distribution of rorquals and Atlantic cod in relation to their prey in the Norwegian high Arctic

AbstractRecent warming in the Barents Sea has led to changes in the spatial distribution of both zooplankton and fish, with boreal communities expanding northwards. A similar northward expansion has been observed in several rorqual species that migrate into northern waters to take advantage of high summer productivity, hence feeding opportunities. Based on ecosystem surveys conducted during August–September in 2014–2017, we investigated the spatial associations among the three rorqual species of blue, fin, and common minke whales, the predatory fish Atlantic cod, and their main prey groups (zooplankton, 0-group fish, Atlantic cod, and capelin) in Arctic Ocean waters to the west and north of Svalbard. During the surveys, whale sightings were recorded by dedicated whale observers on the bridge of the vessel, whereas the distribution and abundance of cod and prey species were assessed using trawling and acoustic methods. Based on existing knowledge on the dive habits of these rorquals, we divided our analyses into two depth regions: the upper 200 m of the water column and waters below 200 m. Since humpback whales were absent in the area in 2016 and 2017, they were not included in the subsequent analyses of spatial association. No association or spatial overlap between fin and blue whales and any of the prey species investigated was found, while associations and overlaps were found between minke whales and zooplankton/0-group fish in the upper 200 m and between minke whales and Atlantic cod at depths below 200 m. A prey detection range of more than 10 km was suggested for minke whales in the upper water layers.

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Summer phytoplankton of the northern Barents Sea (75–80º N)

Hydrosphere Еcology (Экология гидросферы) ◽

10.33624/2587-9367-2019-2(4)-8-19 ◽

2019 ◽

pp. 8-19

Author(s):

Larisa A. Pautova ◽

Vladimir A. Silkin ◽

Marina D. Kravchishina ◽

Valeriy G. Yakubenko ◽

Anna L. Chultsova

Keyword(s):

Barents Sea ◽

Weighted Average ◽

Arctic Basin ◽

High Arctic ◽

Alexandrium Tamarense ◽

Warm Water ◽

The Arctic ◽

Absolute Maximum ◽

Deep Trench ◽

Maximum Biomass

The structure of the summer planktonic communities of the Northern part of the Barents sea in the first half of August 2017 were studied. In the sea-ice melting area, the average phytoplankton biomass producing upper 50-meter layer of water reached values levels of eutrophic waters (up to 2.1 g/m3). Phytoplankton was presented by diatoms of the genera Thalassiosira and Eucampia. Maximum biomass recorded at depths of 22–52 m, the absolute maximum biomass community (5,0 g/m3) marked on the horizon of 45 m (station 5558), located at the outlet of the deep trench Franz Victoria near the West coast of the archipelago Franz Josef Land. In ice-free waters, phytoplankton abundance was low, and the weighted average biomass (8.0 mg/m3 – 123.1 mg/m3) corresponded to oligotrophic waters and lower mesotrophic waters. In the upper layers of the water population abundance was dominated by small flagellates and picoplankton from, biomass – Arctic dinoflagellates (Gymnodinium spp.) and cold Atlantic complexes (Gyrodinium lachryma, Alexandrium tamarense, Dinophysis norvegica). The proportion of Atlantic species in phytoplankton reached 75%. The representatives of warm-water Atlantic complex (Emiliania huxleyi, Rhizosolenia hebetata f. semispina, Ceratium horridum) were recorded up to 80º N, as indicators of the penetration of warm Atlantic waters into the Arctic basin. The presence of oceanic Atlantic species as warm-water and cold systems in the high Arctic indicates the strengthening of processes of “atlantificacion” in the region.

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Risk Assessment for Key Socio-Economic and Ecological Species in a Sub-Arctic Marine Ecosystem Under Combined Ocean Acidification and Warming

Ecosystems ◽

10.1007/s10021-021-00705-w ◽

2021 ◽

Author(s):

Maartje Oostdijk ◽

Erla Sturludóttir ◽

Maria J. Santos

Keyword(s):

Ocean Acidification ◽

Atlantic Cod ◽

Marine Ecosystem ◽

Keystone Species ◽

Ecosystem Model ◽

The Arctic ◽

Predatory Fish ◽

Important Species ◽

Cascading Effects ◽

Icelandic Waters

AbstractThe Arctic may be particularly vulnerable to the consequences of both ocean acidification (OA) and global warming, given the faster pace of these processes in comparison with global average speeds. Here, we use the Atlantis ecosystem model to assess how the trophic network of marine fishes and invertebrates in the Icelandic waters is responding to the combined pressures of OA and warming. We develop an approach where we first identify species by their economic (catch value), social (number of participants in fisheries), or ecological (keystone species) importance. We then use literature-determined ranges of sensitivity to OA and warming for different species and functional groups in the Icelandic waters to parametrize model runs for different scenarios of warming and OA. We found divergent species responses to warming and acidification levels; (mainly) planktonic groups and forage fish benefited while (mainly) benthic groups and predatory fish decreased under warming and acidification scenarios. Assuming conservative harvest rates for the largest catch-value species, Atlantic cod, we see that the population is projected to remain stable under even the harshest acidification and warming scenario. Further, for the scenarios where the model projects reductions in biomass of Atlantic cod, other species in the ecosystem increase, likely due to a reduction in competition and predation. These results highlight the interdependencies of multiple global change drivers and their cascading effects on trophic organization, and the continued high abundance of an important species from a socio-economic perspective in the Icelandic fisheries.

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Estimated Abundances of Cetacean Species in the Northeast Atlantic from Norwegian Shipboard Surveys Conducted in 2014–2018

NAMMCO Scientific Publications ◽

10.7557/3.4694 ◽

2020 ◽

Vol 11 ◽

Cited By ~ 1

Author(s):

Deanna Leonard ◽

Nils Øien

Keyword(s):

Barents Sea ◽

Humpback Whales ◽

Physeter Macrocephalus ◽

Sperm Whales ◽

Target Species ◽

Independent Observer ◽

Southern Boundary ◽

Norwegian Sea ◽

Northeast Atlantic ◽

Fin Whales

A ship-based mosaic survey of Northeast Atlantic cetaceans was conducted over a 5-year period between 2014–2018. The area surveyed extends from the North Sea in the south (southern boundary at 53oN), to the ice edge of the Barents Sea and the Greenland Sea. Survey vessels were equipped with 2 independent observer platforms that detected whales in passing mode and applied tracking procedures for the target species, common minke whales (Balaenoptera acutorostrata acutorostrata). Here we present abundance estimates for all non-target species for which there were sufficient sightings. We estimate the abundance of fin whales (Balaenoptera physalus) to be 11,387 (CV=0.17, 95% CI: 8,072–16,063), of humpback whales (Megaptera novaeangliae) to be 10,708 (CV=0.38, 95% CI: 4,906–23,370), of sperm whales (Physeter macrocephalus) to be 5,704 (CV=0.26, 95% CI: 3,374–9,643), of killer whales (Orcinus orca) to be 15,056 (CV=0.29, 95% CI: 8,423–26,914), of harbour porpoises (Phocoena phocoena) to be 255,929 (CV=0.20, 95% CI: 172,742–379,175), dolphins of genus Lagenorhynchus to be 192,767 (CV=0.25, 95% CI: 114,033–325,863), and finally of northern bottlenose whales (Hyperoodon ampullatus) to be 7,800 (CV=0.28, 95% CI: 4,373–13,913). Additionally, our survey effort in the Norwegian Sea in 2015 contributed to the 6th North Atlantic Sightings Survey (NASS) and the survey was extended into the waters north and east of Iceland around Jan Mayen island. This NASS extension, along with our Norwegian Sea survey in 2015, was used to estimate the abundance of fin whales, humpback whales, and sperm whales. All estimates presented used mark-recapture distance sampling techniques and were thus corrected for perception bias. Our estimates do not account for additional variance due to distributional shifts between years or biases due to availability or responsive movement.

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Estimated food consumption of minke whales Balaenoptera acutorostrata in Northeast Atlantic waters in 1992-1995

NAMMCO Scientific Publications ◽

10.7557/3.2972 ◽

2000 ◽

Vol 2 ◽

pp. 65 ◽

Cited By ~ 17

Author(s):

Lars P Folkow ◽

Tore Haug ◽

Kjell T Nilssen ◽

Erling S Nordøy

Keyword(s):

Barents Sea ◽

Regional Distribution ◽

Clupea Harengus ◽

Mortality Factor ◽

Point Estimate ◽

Melanogrammus Aeglefinus ◽

Balaenoptera Acutorostrata ◽

Northeast Atlantic ◽

Minke Whales ◽

Prey Items

Data on energy requirements, diet composition, and stock size were combined to estimate the consumption of various prey species by minke whales (Balaenoptera acutorostrata) in Northeast Atlantic waters. In the period 1992-1995, the stock of 85,000 minke whales appeared to have consumed more than 1.8 million tonnes of prey per year in coastal waters off northern Norway, in the Barents Sea and around Spitsbergen during an assumed 6 month stay between mid-April and mid-October.Uncertainties in stock estimates suggest a 95% confidence range of 1.4 - 2.1 million tonnes. The point estimate was composed of 602,000 tonnes of krill Thysanoessa spp., 633,000 tonnes of herring Clupea harengus, 142,000 tonnes of capelin Mallotus villosus, 256,000 tonnes of cod Gadus morhua, 128,000 tonnes of haddock Melanogrammus aeglefinus and 54,500 tonnes of other fish species, including saithe Pollaehius virens and sand eel Ammodytes sp. Consumption of various prey items by minke whales may represent an important mortality factor for some of the species. For example, the estimated annual consumption of herring corresponds to about 70% of the herring fisheries in the Northeast Atlantic in 1995. Minke whale diets are subject to year-to-year variations due to changes in the resource base in different feeding areas. Thus, the regional distribution of consumption of different prey items is highly dynamic.

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Otolith growth and zone formation during first maturity and spawning of Atlantic cod (Gadus morhua)

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/cjfas-2019-0033 ◽

2020 ◽

Vol 77 (1) ◽

pp. 113-123 ◽

Cited By ~ 2

Author(s):

Christian Irgens ◽

Arild Folkvord ◽

Håkon Otterå ◽

Olav S. Kjesbu

Keyword(s):

Gadus Morhua ◽

Barents Sea ◽

Atlantic Cod ◽

Somatic Growth ◽

Otolith Growth ◽

Zone Formation ◽

Stock Biomass ◽

Tank Experiment ◽

The Individual ◽

First Maturity

Specific impacts of somatic growth, sexual maturation, and spawning events on otolith zone formation in Atlantic cod (Gadus morhua) were assessed in a 33-month tank experiment, using Barents Sea cod and Norwegian coastal cod. High and low feeding ration combinations were used to mimic environmental stressors in the field. For both stocks, apparent macrostructural “spawning zones” in otoliths are registered in statutory stock monitoring programs to estimate age at maturity, thus adding key information to stock biomass assessments. We found that substantial energy investments in reproduction caused reductions in otolith growth and altered proportional width between translucent and opaque zones. These effects, however, were only statistically significant among individuals with high reproductive investments, while otoliths from individuals with low investments did not differ from the otoliths for immatures. Reproduction may thus not necessarily induce spawning zones, and alternatively, spawning zones may not necessarily reflect reproduction. Altogether, this suggests that the individual energy level, as a premise for metabolic activity, plays a key role in the formation of such zones and thus is related to environmental conditions.

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Lower Cretaceous Barents Sea strata: epicontinental basin configuration, timing, correlation and depositional dynamics

Geological Magazine ◽

10.1017/s0016756819000918 ◽

2019 ◽

Vol 157 (3) ◽

pp. 458-476 ◽

Cited By ~ 4

Author(s):

Ivar Midtkandal ◽

Jan Inge Faleide ◽

Thea Sveva Faleide ◽

Christopher Sæbø Serck ◽

Sverre Planke ◽

...

Keyword(s):

Sediment Transport ◽

Early Cretaceous ◽

Barents Sea ◽

Source Area ◽

High Arctic ◽

Large Igneous Province ◽

Long Distance ◽

Svalbard Archipelago ◽

Control Factors ◽

Architectural Patterns

AbstractA comprehensive dataset is collated in a study on sediment transport, timing and basin physiography during the Early Cretaceous Period in the Boreal Basin (Barents Sea), one of the world’s largest and longest active epicontinental basins. Long-wavelength tectonic tilt related to the Early Cretaceous High Arctic Large Igneous Province (HALIP) set up a fluvial system that developed from a sediment source area in the NW, which flowed SE across the Svalbard archipelago, terminating in a low-accommodation shallow sea within the Bjarmeland Platform area of the present-day Barents Sea. The basin deepened to the SE with a ramp-like basin floor with gentle dip. Seismic data show sedimentary lobes with internal clinoform geometry that advanced from the NW. These lobes interfingered with, and were overlain by, another younger depositional system with similar lobes sourced from the NE. The integrated data allow mapping of architectural patterns that provide information on basin physiography and control factors on source-to-sink transport and depositional patterns within the giant epicontinental basin. The results highlight how low-gradient, low-accommodation sediment transport and deposition has taken place along proximal to distal profiles for several hundred kilometres, in response to subtle changes in base level and by intra-basinal highs and troughs. Long-distance correlation along depositional dip is therefore possible, but should be treated with caution to avoid misidentification of timelines for diachronous surfaces.

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Predation on herring, Clupea harengus, by minke whales, Balaenoptera acutorostrata, in the Barents Sea

ICES Journal of Marine Science ◽

10.1006/jmsc.2001.1135 ◽

2002 ◽

Vol 59 (1) ◽

pp. 58-70 ◽

Cited By ~ 19

Author(s):

U Lindstrøm

Keyword(s):

Barents Sea ◽

Clupea Harengus ◽

Balaenoptera Acutorostrata ◽

The Barents Sea ◽

Minke Whales

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Individual calling behaviour and movements of North Atlantic minke whales (Balaenoptera acutorostrata)

Behaviour ◽

10.1163/1568539x-00003187 ◽

2014 ◽

Vol 151 (9) ◽

pp. 1335-1360 ◽

Cited By ~ 10

Author(s):

Denise Risch ◽

Ursula Siebert ◽

Sofie M. Van Parijs

Keyword(s):

Social Interactions ◽

North Atlantic ◽

Marine Mammals ◽

Sound Production ◽

Gulf Of Maine ◽

Random Order ◽

Migration Route ◽

Detection Range ◽

Calling Behaviour ◽

Minke Whales

Information on individual calling behaviour and source levels are important for understanding acoustically mediated social interactions of marine mammals, for which visual observations are difficult to obtain. Our study, conducted in the Stellwagen Bank National Marine Sanctuary (SBNMS), located in the Gulf of Maine, USA, used passive acoustic arrays to track North Atlantic minke whales and assess the sound production behaviour of individuals. A total of 18 minke whales were acoustically tracked in this study. Individual calling rates were variable, with a median intercall interval (ICI) of 60.3 s. Average source levels (SLrms) for minke whales pulse trains ranged between 164 and 168 dB re 1 μPa, resulting in a minimum detection range of 0.4–10.2 km for these calls in this urban, coastal environment. All tracked animals were actively swimming at a speed of 5.0 ± 1.2 km/h, which matches swimming speeds of migrating minke whales from other areas and confirms SBNMS as part of the migration route of this species in the Western North Atlantic. Tracked minke whales produced 7 discrete call types belonging to 3 main categories, yet no individual produced all call types. Instead, minke whales produced 2 multisyllabic call sequences (A and B) by combining 3–4 different call types in a non-random order. While 7 of the tracked individuals produced calling pattern A, 10 whales used calling pattern B, and only 1 animal combined call types differently. Animals producing different call sequences were in acoustic range of one another on several occasions, suggesting they may use these sequences for mediating social interactions. The fact that the same calling patterns were shared by several individuals suggests that these patterns may contain information related to sex, age or behavioural context.

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