Combination of a sorting grid and a square mesh panel to optimize size selection in the North-East Arctic cod (Gadus morhua) and redfish (Sebastes spp.) trawl fisheries

2017 ◽  
Vol 75 (3) ◽  
pp. 1105-1116 ◽  
Author(s):  
Manu Sistiaga ◽  
Bent Herrmann ◽  
Eduardo Grimaldo ◽  
Roger B Larsen ◽  
Leonore Olsen ◽  
...  
Keyword(s):  
Gadus Morhua ◽  
Barents Sea ◽  
Selection Process ◽  
Mesh Size ◽  
Species Selection ◽  
North East ◽  
The North ◽  
Potential Alternative ◽  
Escape Path ◽  
Trawl Fisheries

Abstract Sorting grids and square mesh panels are the two most-applied technical devices to supplement codend size- and species-selection in demersal trawls. In the Barents Sea gadoid fishery, the compulsory size-selectivity system comprises a mesh section with a sorting grid followed by a diamond mesh codend. We tested the size-selective performance of a new sorting section that comprised a sorting grid combined with a square mesh panel as a potential alternative for the grid sections currently in use. The new sorting section was shorter and therefore more maneuverable than the existing sorting grid sections. The investigation was carried out on cod and the bycatch species redfish. The grid was found to contribute to the largest proportion of fish release, and the release through the square mesh panel was low. But, the results showed that the grid was successful at guiding fish not escaping through the grid to a second selection process in the panel. However, the square mesh panel did not result on the intended release efficiency except for the smallest sizes of fish, most likely because the guiding angle of the grid and the square meshes in the panel used did not provide a suitable escape path for the desired size range of fish. Therefore, optimizing the mesh size/shape in the panel and/or the guiding angle for the grid potentially could lead to the desired selectivity pattern in the new sorting section.

COMPARISON ESTIMATION OF A POTATOES HYBRIDS IN ECOLOGICAL TEST

1970 ◽  
pp. 25-27
Author(s):  
O. N. Bashlakova ◽  
N. F. Sintsova
Keyword(s):  
Late Blight ◽  
Potato Variety ◽  
Selection Process ◽  
New Potato Variety ◽  
North East ◽  
The North ◽  
Federal Research ◽  
Breeding Station ◽  
Final Yield ◽  
High Degree

The research was carried out in 2017-2019 at the experimental field of the North-east Federal Research Center in the nursery of ecological testing of promising potato hybrids. The aim of the study was to identify hybrids for creating a new potato variety with high early productivity and final yield, attractive appearance of tubers and a high degree of resistance to major potato diseases. As the object of research 8 potato hybrids created at the Falenskaya breeding station — FGBNU FANC of the North-East were used: 27-07 (165-00 x 282-97), 62-08 (9326-2 x Zhukovsky early), 90-09 (194-00 x 45-7-17), 109-11 (183-05 x Dina), 170-08 (Sierra x 93.14-99), 172-11 (59-6-33 x Lazar), 179-10 (Dina x 45-7-17), 455-08 (591m-62 x Dubrava). As a standard was used the Nevsky potato variety zoned in the territory of the Kirov region. The evaluation of potato hybrids was carried out according to the guidelines for the technology of potato selection process: phenological observations, plant productivity on the 65th day from planting, final yield. The numbers 90-09, 170-08 and 179-10 with an early yield of 16.4-17.2 t/ha, an adaptability coefficient higher than 1 and a high degree of resistance to late blight were distinguished by the set of features.

scholarly journals Composition and structure of the parasite faunas of cod, Gadus morhua L. (Teleostei: Gadidae), in the North East Atlantic

2008 ◽  
Vol 1 (1) ◽  
pp. 23 ◽  
Author(s):  
Diana Perdiguero-Alonso ◽  
Francisco E Montero ◽  
Juan Raga ◽  
Aneta Kostadinova
Keyword(s):  
Gadus Morhua ◽  
East Atlantic ◽  
North East ◽  
The North ◽  
Composition And Structure

scholarly journals Potential for codends with shortened lastridge ropes to replace mandated selection devices in demersal trawl fisheries

2021 ◽  
Author(s):  
Manu Sistiaga ◽  
Jesse Brinkhof ◽  
Bent Herrmann ◽  
Roger B. Larsen ◽  
Eduardo Grimaldo ◽  
...  
Keyword(s):  
Gadus Morhua ◽  
Barents Sea ◽  
Size Selectivity ◽  
The Barents Sea ◽  
Alternative Solutions ◽  
Trawl Fisheries

In many trawl fisheries, codend size selectivity is supplemented by adding selection devices to the gear. In the Barents Sea gadoid fishery, combining diamond mesh codends with sorting grids is compulsory. However, the use of grids increases the costs and complexity of the gear, causing discontent among fishermen and prompting researchers to seek alternative solutions. Lastridge ropes are ropes attached to the selvedges of the codend. In this study, we tested the effect of shortening the lastridge ropes of two diamond mesh codends with different mesh sizes on the size selectivity of cod (Gadus morhua), haddock (Melanogramus aeglefinnus), and redfish (Sebastes spp.). Shortening the lastridge ropes by 15% increased the mesh opening during the fishing process, which significantly improved the size-selective properties of the codends. Further, the L50 values were always higher for the codends in the short lastridge configuration. Therefore, codends with shortened lastridge ropes may be a simpler alternative to sorting grids in this fishery, and they may be applicable to many other fisheries in which additional selection devices are used.

scholarly journals Les pêches de l’URSS dans l’Atlantique du Nord-Est et l’élargissement des zones de pêche exclusive

2005 ◽  
Vol 18 (1) ◽  
pp. 107-126
Author(s):  
François Carré
Keyword(s):  
Barents Sea ◽  
East Atlantic ◽  
North East ◽  
The North ◽  
The Barents Sea ◽  
Average Production ◽  
Capelin Mallotus Villosus ◽  
Access Rights ◽  
The Baltic ◽  
Almost All

After the last war, the USSR set it self to increase the development of its ocean fisheries from its two North-East Atlantic seaboards on the Barents Sea and the Baltic. With a modernized fleet and almost complete freedom on the seas, its catch increased six fold between 1950 and 1976, going from 0,4 to 2,5 million tons per year, and Soviet fishermen could be found roaming on all the seas bordering Europe. However, as from 1977, this expansion was fiercely curtailed when coastal nations, including the USSR, established the 200-mile exclusive economic zone (EEZ) or mere exclusive fishing zone (EFZ), each being alloted almost all of its living resource s. More fishing grounds were lost by the USSR than gained, to the point where production suddenly fell in 1977 and it had to turn to fish of lesser quality, often used for industrial purposes, such as the Capelin (Mallotus villosus) and the blue Whiting (Micromesistius poutassou) which today make up to 60 % of all its catch off Northern Europe. The Soviet authorities reacted with flexibility and diversity, namely by increased fishing in the national exclusive zone, particularly in the Barents Sea, through negotiations leading to access rights to foreign waters, particularly those of Norway and the Faeroe Islands, and through a policy whereby it could purchase unprocessed fish from some members of the EEC. Thus Russian factory ships came to the British coasts to process mackerel delivered to them at sea by English and Scottish fishermen. It is through such a strategy of diversification, various examples of which may be found around the world, that the Soviets have succeeded in regaining grounds lost in 1977 and in reaching an average production of 1,7 million tons from 1977 to 1983 in the North-East Atlantic, this being 3 to 4 % less than that of 1970-76, notwithstanding the few purchases of fish made directly at sea.

scholarly journals Diets of the Barents Sea cod (<i>Gadus morhua</i>) from the 1930s to 2018

2021 ◽  
Vol 13 (3) ◽  
pp. 1361-1370
Author(s):  
Bryony L. Townhill ◽  
Rebecca E. Holt ◽  
Bjarte Bogstad ◽  
Joël M. Durant ◽  
John K. Pinnegar ◽  
...  
Keyword(s):  
Gadus Morhua ◽  
Visual Analysis ◽  
Barents Sea ◽  
Atlantic Cod ◽  
Fish Diet ◽  
The North ◽  
The United Kingdom ◽  
Federal Research ◽  
The Barents Sea ◽  
The Uk

Abstract. A new dataset on the diet of Atlantic cod in the Barents Sea from the 1930s to the present day has been compiled to produce one of the largest fish diet datasets available globally. Atlantic cod is one of the most ecologically and commercially important fish species in the North Atlantic. The stock in the Barents Sea is by far the largest, as a result of both successful management and favourable environmental conditions since the early 2000s. As a top predator, cod plays a key role in the Barents Sea ecosystem. The species has a broad diet consisting mainly of crustaceans and teleost fish, and both the amount and type of prey vary in space and time. The data – from Russia, Norway and the United Kingdom – represent quantitative stomach content records from more than 400 000 fish and qualitative data from 2.5 million fish. Many of the data are from joint collaborative surveys between Norway and Russia. The sampling was conducted throughout each year, allowing for seasonal, annual and decadal comparisons to be made. Visual analysis shows cod diets have changed considerably from the start of the dataset in the 1930s to the present day. There was a large proportion of herring in the diets in the 1930s, whereas in more recent decades capelin, invertebrates and other fish dominate. There are also significant interannual asynchronous fluctuations in prey, particularly capelin and euphausiids. Combining these datasets can help us understand how the environment and ecosystems are responding to climatic changes, and what influences the diet and prey switching of cod. Trends in temperature and variability indices can be tested against the occurrence of different prey items, and the effects of fishing pressure on cod and prey stocks on diet composition could be investigated. The dataset will also enable us to improve parametrization of food web models and to forecast how Barents Sea fisheries may respond in the future to management and to climate change. The Russian data are available through joint projects with the Polar Branch of the Russian Federal Research Institute of Fisheries and Oceanography (VNIRO). The UK and Norwegian data (Townhill et al., 2020) are being released with this paper at https://doi.org/10.21335/NMDC-2139169383.

scholarly journals Size selectivity and length-dependent escape behaviour of haddock in a sorting device combining a grid and a square mesh panel

2019 ◽  
Vol 76 (8) ◽  
pp. 1350-1361 ◽  
Author(s):  
Bent Herrmann ◽  
Manu Sistiaga ◽  
Eduardo Grimaldo ◽  
Roger B. Larsen ◽  
Leonore Olsen ◽  
...  
Keyword(s):  
Barents Sea ◽  
Selection Process ◽  
Species Selection ◽  
Melanogrammus Aeglefinus ◽  
Size Selectivity ◽  
Escape Behaviour ◽  
Trawl Fishery ◽  
Haddock Melanogrammus Aeglefinus ◽  
Better Than ◽  
Modelling Approach

Size selectivity of a new sorting section combining a sorting grid and a square mesh panel was tested for haddock (Melanogrammus aeglefinus) in the Barents Sea demersal trawl fishery. Sampling data for a wide size range enabled investigating the selection process for this species in detail, both for the grid and the square mesh panel. Contrary to earlier studies modelling size selectivity for grids and square mesh panels, which assume that the escape behaviour of all sizes of fish is equal, we applied a model that accounted for haddock of different sizes showing different escape behaviours. Our results demonstrated that this model could describe the experimental data collected better than existing models. Specifically, our results showed that the likelihood for smaller haddock to seek escape through the grid and the square mesh panel was higher than that for bigger haddock that still would manage to escape through the devices if they attempted. The new modelling approach presented in this study may be applicable to other species, selection devices, and fisheries.

Marsh vegetation in the north-east of Malozemelskaya tundra

2011 ◽  
pp. 45-69 ◽  
Author(s):  
N. V. Matveyeva ◽  
O. V. Lavrinenko
Keyword(s):  
Barents Sea ◽  
European Part ◽  
Russian Arctic ◽  
Marsh Vegetation ◽  
North East ◽  
The North ◽  
The Barents Sea ◽  
First Time ◽  
Different Levels

For the first time on the north-east of Malozemelskaya tundra at the coast of the Barents Sea the following 5 associations — Puccinellietum phryganodis Hadač 1946 (with subassociations inops Thannheiser, Willers 1988 ex Hofmann 1969 and caricetosum subspatheceае Thannheiser, Willers 1988 nom. nud).; Caricetum subspathaceae Hadač 1946 with subass. Inops Molenaar 1974 and arctanthemetosum hultenii subass. nov. (with variants inops var. nov. and typicum var. nov.); Caricetum glareosae Molenaar 1974 (as a geographical vicariant Calamagrostis deschampsioides vic. nov.) (with subassociations typicum and festucetosum rubrae); Scirpeto—Hippuridetum tetraphyllae Nordh. 1954 (inops subass. nov.), and the Dupontia psilosantha com. type that belong to the three alliance of the Glauco-Puccinellietalia order of the Juncetea maritime class are described with the Braun-Blanquet approach. A provisional ass. Parnassio palustris—Salicetum reptantis ass. nov. prov. represented the transitional vegetation between marshes and tundras belongs to the Scheuchzerio—Caricetea fuscae class. This shows that syntaxa of different levels known previously for various territories outside of the Russian Arctic are rather common at least in its European part. The comparison of the classification units of both Braun-Blanquet and Russian dominant systems (used by A. I. Leskov in the same region in the first half of the last century) has demonstrated a large correspondence in between and the absence of the insuperable barrier between two approaches.

scholarly journals Barents Sea cod (Gadus morhua) diet composition: long-term interannual, seasonal, and ontogenetic patterns

2019 ◽  
Vol 76 (6) ◽  
pp. 1641-1652 ◽  
Author(s):  
Rebecca E Holt ◽  
Bjarte Bogstad ◽  
Joël M Durant ◽  
Andrey V Dolgov ◽  
Geir Ottersen
Keyword(s):  
Gadus Morhua ◽  
Trophic Ecology ◽  
Barents Sea ◽  
Atlantic Cod ◽  
Prey Size ◽  
Ecosystem Dynamics ◽  
Polar Cod ◽  
Important Species ◽  
Predator Prey ◽  
The North

Abstract Atlantic cod (Gadus morhua) is an ecologically and commercially important species in the North-Atlantic region. Cod is a top predator and information on its trophic ecology is integral for understanding predator–prey relationships and food-web dynamics. We present an analysis of the trophic patterns of Barents Sea (BS) cod using a unique 33-year time-series of stomach-content data from 1984 to 2016. We assessed patterns in diet (prey) composition across years, between seasons, as well as ontogenetic trends in diet, including predator–prey size relationships. Ontogenetic shifts in diet were observed, with fish becoming more important prey with increasing cod size. A very early onset of piscivory was found in &lt;20 cm cod. Cannibalism was found in cod &gt; 20 cm and increased with size. Juvenile cod exhibit a tendency towards consuming prey up to 33% of their body length, whereas larger cod feed on all prey sizes, resulting in asymmetric predator–prey size distributions. Diet varied significantly during 1984–2016, consistent with changes in both prey, cod abundance, and distribution. Seasonal differences were observed; capelin dominated the winter diet, whereas cod, polar cod, and other fish species were prevalent in summer/autumn months. This work represents an important step towards understanding trophic linkages that determine BS ecosystem dynamics.

Short communication: New data support phylogeographic patterns in a marine parasite Tristriata anatis (Digenea: Notocotylidae)

2019 ◽  
Vol 94 ◽  
Author(s):  
Anna Gonchar ◽  
Kirill V. Galaktionov
Keyword(s):  
North Pacific ◽  
Barents Sea ◽  
Life Cycles ◽  
Intraspecific Diversity ◽  
Migration Routes ◽  
Arctic Ecosystems ◽  
Reproduction Mode ◽  
North East ◽  
The North ◽  
The North Pacific

Abstract Intraspecific diversity in parasites with heteroxenous life cycles is guided by reproduction mode, host vagility and dispersal, transmission features and many other factors. Studies of these factors in Digenea have highlighted several important patterns. However, little is known about intraspecific variation for digeneans in the marine Arctic ecosystems. Here we analyse an extended dataset of partial cox1 and nadh1 sequences for Tristriata anatis (Notocotylidae) and confirm the preliminary findings on its distribution across Eurasia. Haplotypes are not shared between Europe and the North Pacific, suggesting a lack of current connection between these populations. Periwinkle distribution and anatid migration routes are consistent with such a structure of haplotype network. The North Pacific population appears ancestral, with later expansion of T. anatis to the North Atlantic. Here the parasite circulates widely, but the direction of haplotype transfer from the north-east to the south-west is more likely than the opposite. In the eastern Barents Sea, the local transmission hotspot is favoured.

Management and Developement of Fisheries in the North Atlantic

1973 ◽  
Vol 30 (12) ◽  
pp. 2402-2418 ◽  
Author(s):  
G. Möcklinghoff
Keyword(s):  
Fish Species ◽  
North Atlantic ◽  
Mesh Size ◽  
Fishing Effort ◽  
Conceptual Basis ◽  
East Atlantic ◽  
International Council ◽  
North East ◽  
The North ◽  
The North Atlantic

The "conventional" fish species of the North Atlantic are mostly being fully utilized or nearly so, some having been overexploited in recent years. Recommendations for management are made by the International Commission for the Northwest Atlantic Fisheries (ICNAF) and the North East Atlantic Fisheries Commission (NEAFC). The factual and conceptual basis for management is provided by the scientists of many nations, coordinated by ICNAF and by the International Council for the Exploration of the Sea (ICES). The need in nearly every major North Atlantic fishery is to limit fishing effort, which in practical terms means allocating quotas to states. Such action has been initiated by ICNAF and is under active consideration by NEAFC. The process would have been easier if it had been begun a few years earlier, before several major stocks became depressed, but since new ground is being broken internationally the delay was almost inevitable. Regulations of mesh size in trawls have been in force in both areas for some years. These were successful in providing a greater yield from each year-class of groundfish as it appeared, but could not by themselves ensure a breeding stock adequate for optimum reproduction. Problems of allocation of quotas, of enforcement, and of national claims for the extension of exclusive fishing zones will require continued discussion and goodwill among the nations in the years ahead.

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