scholarly journals Observations on the shoaling behaviour of cod (Gadus callarias) in deep water relative to daylight

1956 ◽  
Vol 35 (2) ◽  
pp. 415-417 ◽  
Author(s):  
G. H. Ellis
Keyword(s):  
Light Intensity ◽  
Laboratory Experiment ◽  
Deep Water ◽  
Barents Sea ◽  
Physical Factor ◽  
Commercial Fishing ◽  
Depth Range ◽  
The Barents Sea ◽  
Shoaling Behaviour ◽  
Factor Governing

It is well known that vision is the main physical factor governing the formation and maintenance offish shoals, and that, in general, shoals break up when the light intensity falls below a certain level. Breder (1929, 1942), Newman (1876), Parr (1927, 1931), and others, have shown this by laboratory experiment.During a commercial fishing voyage to the Barents Sea it became possible, by means of a recording echo-sounder, to study the shoaling behaviour of cod in deep water relative to light intensity. The observations were made aboard the Hull trawler Lancella whilst fishing in a depth of 110 fathoms at Skolpen Bank in September 1955. For this a Kelvin and Hughes recording echosounder type MS. 24J was used, the depth range across the chart being 55 fathoms. The scale was phased so that the region between 80 and 135 fathoms deep was displayed.

scholarly journals Bycatch reduction in the deep-water shrimp (Pandalus borealis) trawl fishery by increasing codend mesh openness

2021 ◽  
Author(s):  
Nadine Jacques ◽  
Hermann Pettersen ◽  
Kristine Cerbule ◽  
Bent Herrmann ◽  
Ólafur A. Ingólfsson ◽  
...  
Keyword(s):  
Deep Water ◽  
Barents Sea ◽  
Juvenile Fish ◽  
Size Selectivity ◽  
Pandalus Borealis ◽  
Trawl Fishery ◽  
Bycatch Reduction ◽  
Drag Forces ◽  
The Barents Sea ◽  
Trawl Fisheries

In most trawl fisheries, drag forces tend to close the meshes in large areas of diamond mesh codends, negatively affecting their selective potential. In the Barents Sea deep-water shrimp (Pandalus borealis) trawl fishery, selectivity is based on a sorting grid followed by a diamond mesh codend. However, the retention of juvenile fish as well as undersized shrimp is still a problem. In this study, we estimated the effect of applying different codend modifications, each aimed at affecting codend mesh openness and thereby selectivity. Changing from a 4-panel to a 2-panel construction of the codend did not affect size selectivity. Shortening the lastridge ropes of a 4-panel codend by 20% resulted in minor reductions for juvenile fish bycatch, but a 45% reduction of undersized shrimp was observed. Target-size catches of shrimp were nearly unaffected. When the codend mesh circumference was reduced while simultaneously shortening the lastridge ropes, the effect on catch efficiency for shrimp or juvenile fish bycatch was marginal compared to a 4-panel codend design with shortened lastridge ropes.

First assessment of biomass and abundance of cephalopods Rossia palpebrosa and Gonatus fabricii in the Barents Sea

2016 ◽  
Vol 97 (8) ◽  
pp. 1605-1616 ◽  
Author(s):  
Alexey V. Golikov ◽  
Rushan M. Sabirov ◽  
Pavel A. Lubin
Keyword(s):  
Deep Water ◽  
Barents Sea ◽  
World Ocean ◽  
The Arctic ◽  
Arctic Ecosystems ◽  
Climate Conditions ◽  
Quantitative Distribution ◽  
Maximum Biomass ◽  
The Barents Sea ◽  
The Impact

Studies on the quantitative distribution of cephalopods in the Arctic are limited, and almost completely absent for the Barents Sea. It is known that the most abundant cephalopods in the Arctic are Rossia palpebrosa and Gonatus fabricii. Their biomass and abundance have been assessed for the first time in the Barents Sea and adjacent waters. The maximum biomass of R. palpebrosa in the Barents Sea was 6.216–6.454 thousand tonnes with an abundance of 521.5 million specimens. Increased densities of biomass were annually registered in the north-eastern parts of the Barents Sea. The maximum biomass of G. fabricii in the Barents Sea was 24.797 thousand tonnes with an abundance of 1.705 billion specimens. The areas with increased density of biomass (higher than 100 kg km−2) and abundance (more than 10,000 specimens km−2) were concentrated in deep-water troughs in the marginal parts of the Barents Sea and in adjacent deep-water areas. The biomass and abundance of R. palpebrosa and G. fabricii in the Barents Sea were much lower than those of major taxa of invertebrates and fish and than those of cephalopods in other parts of the World Ocean. It has been suggested that the importance of cephalopods in the Arctic ecosystems, at least in terms of quantitative distribution, could be somewhat lower than in the Antarctic or the tropics. Despite the impact of ongoing warming of the Arctic on the distribution of cephalopods being described repeatedly already, no impact of the current year's climate on the studied species was found. The only exception was the abundance of R. palpebrosa, which correlated with the current year's climate conditions.

scholarly journals Escape mortality of cod, saithe, and haddock in a Barents Sea trawl fishery

2007 ◽  
Vol 64 (9) ◽  
pp. 1836-1844 ◽  
Author(s):  
Ólafur Arnar Ingólfsson ◽  
Aud Vold Soldal ◽  
Irene Huse ◽  
Mike Breen
Keyword(s):  
Barents Sea ◽  
Fish Length ◽  
Commercial Fishing ◽  
Experimental Conditions ◽  
Closely Related Species ◽  
Large Variability ◽  
Trawl Fishery ◽  
The Barents Sea ◽  
Methodological Problems ◽  
Low Levels

Abstract Ingólfsson, Ó. A., Soldal, A. V., Huse, I., and Breen, M. 2007. Escape mortality of cod, saithe, and haddock in a Barents Sea trawl fishery. – ICES Journal of Marine Science, 64: 000–000. We investigated the survival of gadoid fish in the Barents Sea escaping from a demersal trawl during commercial fishing conditions, with and without a sorting grid, at high and low levels of fishing intensity. The mortality of cod and saithe was negligible and unrelated to experimental conditions. Haddock mortality was generally greater than observed in earlier experiments and inversely related to fish length. Any possible effects of experimental conditions were hidden by large variability in the observed rates of mortality. We conclude that the observed mortality of haddock is confounded by methodological problems, particularly the instability of the observation cages, and does not reflect the true escape mortality. Cod and saithe are capable of surviving the stress of passage through, and escape from, the trawl, whereas haddock are more vulnerable, despite being a closely related species.

scholarly journals Observations of water masses and circulation with focus on the Eurasian Basin of the Arctic Ocean from the 1990s to the late 2000s

Ocean Science ◽  
2013 ◽  
Vol 9 (1) ◽  
pp. 147-169 ◽  
Author(s):  
B. Rudels ◽  
U. Schauer ◽  
G. Björk ◽  
M. Korhonen ◽  
S. Pisarev ◽  
...  
Keyword(s):  
Deep Water ◽  
Barents Sea ◽  
The Arctic ◽  
Laptev Sea ◽  
Fram Strait ◽  
Gakkel Ridge ◽  
Geothermal Heating ◽  
The Barents Sea ◽  
Eurasian Basin ◽  
The Laptev Sea

Abstract. The circulation and water mass properties in the Eurasian Basin are discussed based on a review of previous research and an examination of observations made in recent years within, or parallel to, DAMOCLES (Developing Arctic Modeling and Observational Capabilities for Long-term Environmental Studies). The discussion is strongly biased towards observations made from icebreakers and particularly from the cruise with R/V Polarstern 2007 during the International Polar Year (IPY). Focus is on the Barents Sea inflow branch and its mixing with the Fram Strait inflow branch. It is proposed that the Barents Sea branch contributes not just intermediate water but also most of the water to the Atlantic layer in the Amundsen Basin and also in the Makarov and Canada basins. Only occasionally would high temperature pulses originating from the Fram Strait branch penetrate along the Laptev Sea slope across the Gakkel Ridge into the Amundsen Basin. Interactions between the Barents Sea and the Fram Strait branches lead to formation of intrusive layers, in the Atlantic layer and in the intermediate waters. The intrusion characteristics found downstream, north of the Laptev Sea are similar to those observed in the northern Nansen Basin and over the Gakkel Ridge, suggesting a flow from the Laptev Sea towards Fram Strait. The formation mechanisms for the intrusions at the continental slope, or in the interior of the basins if they are reformed there, have not been identified. The temperature of the deep water of the Eurasian Basin has increased in the last 10 yr rather more than expected from geothermal heating. That geothermal heating does influence the deep water column was obvious from 2007 Polarstern observations made close to a hydrothermal vent in the Gakkel Ridge, where the temperature minimum usually found above the 600–800 m thick homogenous bottom layer was absent. However, heat entrained from the Atlantic water into descending, saline boundary plumes may also contribute to the warming of the deeper layers.

scholarly journals Ice gouging on the arctic shelf of Russia

2019 ◽  
Vol 59 (3) ◽  
pp. 466-468
Author(s):  
S. L. Nikiforov ◽  
R. A. Ananiev ◽  
N. V. Libina ◽  
N. N. Dmitrevskiy ◽  
L. I. Lobkovskii
Keyword(s):  
Deep Water ◽  
Barents Sea ◽  
The Arctic ◽  
Natural Phenomena ◽  
Novaya Zemlya ◽  
The Barents Sea ◽  
Franz Josef Land ◽  
Eastern Shelf ◽  
Almost All ◽  
Perennial Ice

The results of recent geological and geophysical expeditions indicate the activation of hazardous natural phenomena associated with ice gouging and represent geohazard for almost all activities, including operation of the Northern Sea Route. Within the Barents Sea and the western part of the Kara Sea, the modern ice gouging is mainly associated with icebergs which are formed as a result of the destruction of the glaciers of Novaya Zemlya, the Spitsbergen archipelago and Franz Josef Land, while on the eastern shelf it is caused by the destruction of seasonal or perennial ice fields. Fixed furrows can be divided into modern coastal gouges or deep water ploughmarks. All deep water gouges within the periglacial and glacial shelf are of paleogeographical origin, but with different mechanisms of action on the seabed. These furrows were formed by floating ice on the periglacial shelf. On the glacial shelf deep water ploughmarks were formed by large icebergs, which could carry out the gouging even on the continental slope and deep-sea ridges of the Arctic Ocean.

scholarly journals Distribution of Nereilinum murmanicum (Annelida, Siboglinidae) in the Barents Sea in the Context of Its Oil and Gas Potential

2021 ◽  
Vol 9 (12) ◽  
pp. 1339
Author(s):  
Nadezda Karaseva ◽  
Madina Kanafina ◽  
Mikhail Gantsevich ◽  
Nadezhda Rimskaya-Korsakova ◽  
Denis Zakharov ◽  
...  
Keyword(s):  
Hydrogen Sulfide ◽  
Oil And Gas ◽  
Barents Sea ◽  
Arctic Basin ◽  
Gas Production ◽  
The Arctic ◽  
Depth Range ◽  
Oxidation Of Methane ◽  
The Barents Sea ◽  
High Concentrations

Frenulate siboglinids are a characteristic component of communities living in various reducing environments, including sites with hydrocarbon seeps. High concentrations of hydrocarbons in the sediments of the Arctic basin seas, including the Barents Sea, suggest the presence of a rich siboglinid fauna there. This reflects the fact that microbiological oxidation of methane occurs under reducing conditions, generating high concentrations of hydrogen sulfide in the sediment. This hydrogen sulfide acts as an energy source for the sulfide-oxidizing symbionts of siboglinids. Here we report on the findings of the frenulate siboglinid species Nereilinum murmanicum made between 1993 and 2020 in the Barents Sea. These data significantly expand the range of this species and yield new information on its habitat distribution. The depth range of N. murmanicum was 75–375 m. The species was most abundant from 200 to 350 m and was associated with temperatures below 3 °C and salinities from 34.42 to 35.07. Most of the findings (43 locations or 74%) fall on areas highly promising for oil and gas production. Twenty-eight locations (48%) are associated with areas of known oil deposits, 22 locations (37%) with explored areas of gas hydrate deposits. N. murmanicum was also found near the largest gas fields in the Barents Sea, namely Shtokman, Ludlovskoye and Ledovoye.

scholarly journals Observations of water masses and circulation in the Eurasian Basin of the Arctic Ocean from the 1990s to the late 2000s

2012 ◽  
Vol 9 (4) ◽  
pp. 2695-2747
Author(s):  
B. Rudels ◽  
U. Schauer ◽  
G. Björk ◽  
M. Korhonen ◽  
S. Pisarev ◽  
...  
Keyword(s):  
Deep Water ◽  
Barents Sea ◽  
The Arctic ◽  
Laptev Sea ◽  
Fram Strait ◽  
Gakkel Ridge ◽  
Geothermal Heating ◽  
The Barents Sea ◽  
Eurasian Basin ◽  
The Laptev Sea

Abstract. The circulation and water mass properties in the Eurasian Basin are discussed based on a review of previous research and an examination of observations made in recent years within, or parallel to, DAMOCLES (Developing Arctic Modelling and Observational Capabilities for Long-term Environmental Studies). The discussion is strongly biased towards observations made from icebreakers and particularly from the cruise with R/V Polarstern 2007 during the International Polar Year (IPY). Focus is on the Barents Sea inflow branch and its mixing with the Fram Strait inflow branch. It is proposed that the Barents Sea branch contributes not just intermediate water but also most of the Atlantic layer that is found in the Amundsen Basin and also in the Makarov and Canada basins. Only occasionally would high temperature pulses originating from the Fram Strait branch penetrate along the Laptev Sea slope across the Gakkel Ridge into the Amundsen Basin. Interactions between the Barents Sea and the Fram Strait branches lead to formation of intrusive layers, in the Atlantic layer and in the intermediate waters. The intrusion characteristics found downstream north of the Laptev Sea are similar to those observed in the Northern Nansen Basin and over the Gakkel Ridge, implying a flow from the Laptev Sea towards Fram Strait. The formation mechanisms for the intrusions at the continental slope, or in the interior of the basins if they are reformed there, have not been identified. The temperature of the deep water of the Eurasian Basin has increased in the last 10 yr rather more than expected from geothermal heating. That geothermal heating does influence the deep water column was obvious from 2007 Polarstern observations made close to a hydrothermal vent in the Gakkel Ridge, where the temperature minimum usually found above the 600–800 m thick homogenous bottom layer was absent. However, heat entrained from the Atlantic water into descending boundary plumes may also contribute to the warming of the deeper layers.

scholarly journals Barents Sea megabenthos: Spatial and temporal distribution and production

2020 ◽  
Vol 5 (2) ◽  
pp. 19-37
Author(s):  
D. V. Zakharov ◽  
L. L. Jørgensen ◽  
I. E. Manushin ◽  
N. A. Strelkova
Keyword(s):  
Barents Sea ◽  
Atlantic Cod ◽  
Temporal Trends ◽  
Temporal Distribution ◽  
The Arctic ◽  
Sampling Effort ◽  
Depth Range ◽  
The Barents Sea ◽  
Production Values

This long-term observation of the faunal composition within the Barents Sea provides a benchmark for monitoring community changes caused by oceanographic variability, fishery activities, and crab predators (Chionoecetes opilio, Paralithodes camtschaticus), whose populations have been rapidly growing and spreading in recent years. In the Arctic systems, megabenthic communities comprise a significant part of benthic biomass and play an important role in carbon cycling on continental shelves. The gradual accumulation of knowledge on megabenthos may make it possible to assess their role in the ecosystem and ultimately contribute to a more rational management of the Barents Sea resources. This article represents an important series of long-term megabenthic observations in the Barents Sea. The main goal of our research is to identify spatial patterns and temporal trends in the megabenthic part of communities, including changes in the biomass and production values. As a part of the joint Norwegian-Russian ecosystem surveys, benthic experts have been identifying the invertebrates (megafauna) collected by bottom trawls during annual assessments of commercial stocks, such as Atlantic cod (Gadus morhua) and northern shrimp (Pandalus borealis). The sampling equipment used was a Campelen 1800 bottom trawl, rigged with rockhopper ground gear and towed on double warps, and standardized to a fixed sampling effort (equivalent to a towing distance of 0.75 nautical miles (nm), or 1.4 km). The processing of the biological material was conducted in accordance with standardized procedures, following the retrieval of each trawl. This work represents data from 5016 stations from 2005 to 2017, with a total sampled biomass of 238.4 tons and 14.9 million individual organisms. In total, 694 megabenthic species (1058 taxa) have been recorded, with the greatest diversity observed in the depth range of 100–400 m, while the largest mean catches were taken between depths of 600–800 m. The biomass (B) and production (P) values of the benthic megafauna were approximately stable during the 9 years of investigation, although there was a decreasing trend after 2014. The annual production P/B ratio of megabenthos was calculated to be at 0.3. The distribution, contribution to production, and gross biomass values of the megabenthos had been underestimated in the previous studies of zoobenthos. The results from this research show that, in the current warm period, the majority of the Barents Sea is in an intermediate state between the Arctic and boreal regions due to the wide distribution of boreal species toward the north. The dynamics of the mean biogeographical index (the border between areas of the dominance of boreal and Arctic species) within the central-southern part of the Barents Sea suggests that a large part of the area can be characterized as predominantly boreal intermediate since 2013.

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