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 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.

scholarly journals Effect of gear design on catch damage on cod (Gadus morhua) in the Barents Sea demersal trawl fishery

Food Control ◽  
2021 ◽  
Vol 120 ◽  
pp. 107562 ◽  
Author(s):  
Jesse Brinkhof ◽  
Bent Herrmann ◽  
Manu Sistiaga ◽  
Roger B. Larsen ◽  
Nadine Jacques ◽  
...  
Keyword(s):  
Gadus Morhua ◽  
Barents Sea ◽  
Trawl Fishery ◽  
Gear Design ◽  
The Barents Sea

Organic matter and its transformation rates in different sea ecosystems

2021 ◽  
pp. 212-235
Author(s):  
A.I. Agatova ◽  
◽  
N.M. Lapina ◽  
N.I. Torgunova ◽  
K.V. Kodryan ◽  
...  
Keyword(s):  
Organic Matter ◽  
Particulate Organic Matter ◽  
High Latitude ◽  
Barents Sea ◽  
Qualitative Composition ◽  
Large Variability ◽  
Deep Waters ◽  
The Barents Sea ◽  
Oil Hydrocarbons ◽  
Significant Intensification

The article includes proprietary data and data from literature from the last 30 years about the fluctuations in concentration and the elemental and biochemical make-up of the dissolved and particulate organic matter (DOM and POM, respectively) in the different ecosystems of the Barents Sea. The large variability of these values in both surface and deep waters is shown, depending on the intensity of the hydrological and biological processes.DOM concentrations varied from 59 to 664 μMCorg, while POM varied from 0.25 to 38.08 μMCorg. The reduction of the ice cover affected both the distribution and the qualitative composition of the DOM and the POM. This reduction, as well as the increased flow of Atlantic waters, contributed not only to an increase in the primary production of organic matter, but also to a significant intensification of redox and hydrolytic processes of its transformation, especially in the high-latitude part of the Barents Sea. The DOM of the sea is characterized by high C / P ratios, far exceeding those of Redfeld. At the same time, C / N ratios in the most productive waters are close to those of Redfeld. We highlighted four regions in the sea where concentrations of dissolved carbohydrates increase towards the bottom, which indicates that oil hydrocarbons are supplied here.

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 Effect of a quality-improving cod end on size selectivity and catch patterns of cod in bottom trawl fishery

2019 ◽  
Vol 76 (11) ◽  
pp. 2110-2120 ◽  
Author(s):  
Jesse Brinkhof ◽  
Bent Herrmann ◽  
Roger B. Larsen ◽  
Tiago Veiga-Malta
Keyword(s):  
Gadus Morhua ◽  
Barents Sea ◽  
Relative Size ◽  
Bottom Trawl ◽  
Size Selectivity ◽  
Total Size ◽  
Trawl Fishery ◽  
The Barents Sea ◽  
Sea Bottom ◽  
Significant Difference

A new cod-end concept developed and tested exhibited significantly improved quality of caught cod (Gadus morhua) compared with that of the conventional cod end used in the Barents Sea bottom trawl fishery. However, the design of the new quality-improving cod end raised concerns about its size selectivity and the possibility that higher retention probability could negatively impact the catch pattern by increasing the proportion of undersized cod. Therefore, the goal of this study was to quantify and compare the size selectivity and catch pattern for cod when deploying, respectively, the conventional and new quality-improving cod end in the Barents Sea bottom trawl fishery. The new quality-improving cod end had significantly lower relative size selectivity than the conventional cod end, but no significant difference in the catch patterns was detected in the trawl. Further, estimation of the total size selectivity in the trawl revealed that the increased retention of small cod when using the quality-improving cod end was minor. Hence, despite the reduced selectivity, the quality-improving cod end can be used with low risk of retaining small cod.

scholarly journals Effect of three different codend designs on the size selectivity of juvenile cod in the Barents Sea shrimp trawl fishery

2019 ◽  
Vol 219 ◽  
pp. 105337
Author(s):  
Bent Herrmann ◽  
Manu Sistiaga ◽  
Roger B. Larsen ◽  
Jesse Brinkhof
Keyword(s):  
Barents Sea ◽  
Size Selectivity ◽  
Trawl Fishery ◽  
The Barents Sea ◽  
Shrimp Trawl

scholarly journals Methods and results of in situ target-strength measurements of Atlantic cod (Gadus morhua) during combined trawl-acoustic surveys

2009 ◽  
Vol 66 (6) ◽  
pp. 1225-1232 ◽  
Author(s):  
Viacheslav A. Ermolchev
Keyword(s):  
Gadus Morhua ◽  
Barents Sea ◽  
Atlantic Cod ◽  
Biological Data ◽  
Target Strength ◽  
Fish Length ◽  
The Barents Sea ◽  
Total Fish ◽  
Acoustic Surveys

Abstract Ermolchev, V. A., 2009. Methods and results of in situ target-strength measurements of Atlantic cod (Gadus morhua) during combined trawl-acoustic surveys. – ICES Journal of Marine Science, 66: 1225–1232. This paper presents methods for collecting acoustic and biological data, including in situ target-strength (TS) estimates of fish, with results presented for Atlantic cod (Gadus morhua) obtained from combined trawl-acoustic surveys. These include fish in the small, average, and maximum length classes, within the range 5–136 cm (total fish length, LT). The investigations were done using Simrad EK500/EK60 echosounders with split-beam transducers and special post-processing software. Based on an analysis of data collected in the Barents Sea during 1998–2007, a relationship TS = 25.2 log10(LT) − 74.8 was obtained for Atlantic cod at 38 kHz, with TS in dB and LT in centimetres. Seasonally, and for depths between 50 and 500 m, the variability in cod TS was 3.1 dB, decreasing with depth. The largest day–night difference in mean TS was in August–September, with changes as large as 1.0–1.7 dB. In the other seasons, the day–night difference was <1.0 dB.

scholarly journals Fisheries change spawning ground distribution of northeast Arctic cod

2009 ◽  
Vol 6 (2) ◽  
pp. 261-264 ◽  
Author(s):  
Anders Frugård Opdal
Keyword(s):  
Barents Sea ◽  
Size Structure ◽  
Sudden Increase ◽  
Spawning Grounds ◽  
Norwegian Coast ◽  
Trawl Fishery ◽  
Climatic Variations ◽  
The Barents Sea ◽  
Spawning Stock

Prior to the 1920s, the northeast Arctic (NA) cod were caught at spawning grounds ranging from the southernmost to the northernmost parts of the Norwegian coast, but have for the last 50 yr mainly been caught around the Lofoten archipelago and northwards. The NA cod have their feeding and nursery grounds in the Barents Sea, and migrate south towards the Norwegian coast in the winter to spawn. This study uses commercial fisheries' data from landing ports along the entire Norwegian coast during the period 1866–1969 as evidence of long-term truncation and northerly shift of spawning grounds. Nearly all spawning grounds south of Lofoten have been abandoned, while an increasing proportion of the spawning stock only uses the northernmost areas of the Norwegian coast, Troms and Finnmark. The truncation can hardly be attributed to long-term climatic variations, but may result from an intensive size-selective trawl fishery in the Barents Sea causing a sudden increase in fishing mortality, probably altering the size structure and migratory capacity of the stock.

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