Do abiotic mechanisms determine interannual variability in length-at-age of juvenile Arcto-Norwegian cod?

2002 ◽  
Vol 59 (1) ◽  
pp. 57-65 ◽  
Author(s):  
Geir Ottersen ◽  
Kristin Helle ◽  
Bjarte Bogstad
Keyword(s):  
Growth Rates ◽  
Gadus Morhua ◽  
Barents Sea ◽  
Water Masses ◽  
Inverse Relation ◽  
Lower Growth ◽  
Density Dependent ◽  
The Barents Sea ◽  
The Mean ◽  
Dependent Growth

For the large Arcto-Norwegian stock of cod (Gadus morhua L.) in the Barents Sea, year-to-year variability in growth is well documented. Here three hypotheses for the observed inverse relation between abundance and the mean length-at-age of juveniles (ages 1–4) are suggested and evaluated. Based on comprehensive data, we conclude that year-to-year differences in length-at-age are mainly determined by density-independent mechanisms during the pelagic first half year of the fishes' life. Enhanced inflow from the southwest leads to an abundant cohort at the 0-group stage being distributed farther east into colder water masses, causing lower postsettlement growth rates. We can not reject density-dependent growth effects related to variability in food rations, but our data do not suggest this to be the main mechanism. Another hypothesis suggests that lower growth rates during periods of high abundance are a result of density-dependent mechanisms causing the geographic range of juveniles to extend eastwards into colder water masses. This is rejected mainly because year-to-year differences in mean length are established by age 2, which is too early for movements over large distances.

Method application of optimal multi-parameter analysis to assess the distribution of water masses as an example of CTD data of the Barents Sea in summer 2017

2019 ◽  
pp. 38-51
Author(s):  
Valeriy G. Yakubenko ◽  
Anna L. Chultsova
Keyword(s):  
Barents Sea ◽  
Field Measurements ◽  
Structural Similarity ◽  
Water Masses ◽  
Parameter Analysis ◽  
Water Dynamics ◽  
Phosphorus Concentration ◽  
Nitrogen And Phosphorus ◽  
The Barents Sea ◽  
Expert Assessments

Identification of water masses in areas with complex water dynamics is a complex task, which is usually solved by the method of expert assessments. In this paper, it is proposed to use a formal procedure based on the application of the method of optimal multiparametric analysis (OMP analysis). The data of field measurements obtained in the 68th cruise of the R/V “Academician Mstislav Keldysh” in the summer of 2017 in the Barents Sea on the distribution of temperature, salinity, oxygen, silicates, nitrogen, and phosphorus concentration are used as a data for research. A comparison of the results with data on the distribution of water masses in literature based on expert assessments (Oziel et al., 2017), allows us to conclude about their close structural similarity. Some differences are related to spatial and temporal shifts of measurements. This indicates the feasibility of using the OMP analysis technique in oceanological studies to obtain quantitative data on the spatial distribution of different water masses.

scholarly journals Comparison of shortest sailing distance through random and regular sampling points

2004 ◽  
Vol 61 (1) ◽  
pp. 140-147 ◽  
Author(s):  
Alf Harbitz ◽  
Michael Pennington
Keyword(s):  
Random Sampling ◽  
Minimum Distance ◽  
Barents Sea ◽  
Pandalus Borealis ◽  
The Barents Sea ◽  
Theoretical Sampling ◽  
Sampling Points ◽  
Regular Sampling ◽  
The Mean ◽  
The Difference

Abstract The shortest sailing distance through n sampling points is calculated for simple theoretical sampling domains (square and circle) as well as for a rather irregular and concavely shaped real sampling domain in the Barents Sea. The sampling sites are either located at the nodes of a square grid (regular sampling) or they are randomly distributed. For n less than ten, the exact shortest sailing distance is derived. For larger n, a traveling salesman algorithm (simulated annealing) was applied, and its bias (distance from true minimum) was estimated based on a case where the true minimum distance was known. In general, the average minimum sailing distance based on random sampling was considerably shorter than for regular sampling, and the difference increased with sample size until an asymptotic value was reached at about n=60 for a square domain. For the sampling domain in the Barents Sea used for shrimp (Pandalus borealis) abundance surveys (n=118 stations), the cruise-track lengths based on random sampling were approximately normally distributed. The mean sailing distance was 18% shorter than the cruise track for regular sampling and the standard deviation equalled 2.6%.

scholarly journals On the diversity of settlements of the bivalve mollusk Macoma calcarea (Bivalvia,Tellinidae) off the coast of Novaya Zemlya.

2020 ◽  
Vol 11 (5-2020) ◽  
pp. 116-125
Author(s):  
A.E. Noskovich ◽  
Keyword(s):  
High Mortality ◽  
Barents Sea ◽  
Bivalve Mollusk ◽  
Water Masses ◽  
High Biomass ◽  
Size Classes ◽  
Novaya Zemlya ◽  
The Barents Sea ◽  
Group I ◽  
Silty Soils

In the eastern part of the Barents Sea, there are 3 types of settlements of the bivalve mollusk Macoma calcarea. At low positive temperatures (from 0.6 to 1.3 оC),juveniles predominate on sandy-silty soils in settlements with low biomass, uneven growth and high mortality. In colder water masses (–0.4...–1.5 оC), M. calcareasettlements consist of long-lived, evenly growing large individuals that form high biomass values. In the settlement of group I, there was an increased elimination of certain size classes. The distribution of settlements depends little on the depth and salinity.

scholarly journals Marine mammals' influence on ecosystem processes affecting fisheries in the Barents Sea is trivial

2009 ◽  
Vol 5 (2) ◽  
pp. 204-206 ◽  
Author(s):  
Peter J Corkeron
Keyword(s):  
Marine Mammal ◽  
Marine Mammals ◽  
Gadus Morhua ◽  
Fishery Management ◽  
Barents Sea ◽  
Scientific Evidence ◽  
Primary Component ◽  
Clupea Harengus ◽  
Balaenoptera Acutorostrata ◽  
The Barents Sea

Some interpretations of ecosystem-based fishery management include culling marine mammals as an integral component. The current Norwegian policy on marine mammal management is one example. Scientific support for this policy includes the Scenario Barents Sea (SBS) models. These modelled interactions between cod, Gadus morhua , herring, Clupea harengus , capelin, Mallotus villosus and northern minke whales, Balaenoptera acutorostrata . Adding harp seals Phoca groenlandica into this top-down modelling approach resulted in unrealistic model outputs. Another set of models of the Barents Sea fish–fisheries system focused on interactions within and between the three fish populations, fisheries and climate. These model key processes of the system successfully. Continuing calls to support the SBS models despite their failure suggest a belief that marine mammal predation must be a problem for fisheries. The best available scientific evidence provides no justification for marine mammal culls as a primary component of an ecosystem-based approach to managing the fisheries of the Barents Sea.

Pseudobranchial tumours in Atlantic cod, Gadus morhua L., from the Barents Sea

1981 ◽  
Vol 4 (6) ◽  
pp. 527-532 ◽  
Author(s):  
E. C. EGIDIUS ◽  
J. V. JOHANNESSEN ◽  
E. LANGE
Keyword(s):  
Gadus Morhua ◽  
Barents Sea ◽  
Atlantic Cod ◽  
The Barents Sea

Comparison of DNA damage in the early life stages of cod, Gadus morhua, originating from the Barents Sea and Baltic Sea

1996 ◽  
Vol 42 (1-4) ◽  
pp. 119-123 ◽  
Author(s):  
Gunilla Ericson ◽  
Gun Åkerman ◽  
Birgitta Liewenborg ◽  
Lennart Balk
Keyword(s):  
Dna Damage ◽  
Baltic Sea ◽  
Early Life ◽  
Gadus Morhua ◽  
Barents Sea ◽  
Life Stages ◽  
Early Life Stages ◽  
The Barents Sea

scholarly journals Reproductive strategy of a migratory fish stock: implications of spatial variations in natural mortality

2016 ◽  
Vol 73 (12) ◽  
pp. 1742-1749 ◽  
Author(s):  
Øystein Langangen ◽  
Geir Ottersen ◽  
Lorenzo Ciannelli ◽  
Frode B. Vikebø ◽  
Leif Christian Stige
Keyword(s):  
Reproductive Strategy ◽  
Early Life ◽  
Gadus Morhua ◽  
Barents Sea ◽  
Spatial Variations ◽  
Fish Stock ◽  
Life Stages ◽  
Early Life Stages ◽  
The Barents Sea ◽  
Survival And Growth

We investigate how the reproductive strategy in a migratory marine fish may be influenced by spatial variations in mortality in early life stages. In particular, we examine how spawning time and location affect offspring survival and growth. A drift model for early life stages (eggs to age 1) of the Barents Sea cod (Gadus morhua) is combined with empirical estimates of spatial variation in mortality at two different life stages. We examine seasonal and interannual differences in survival and growth in offspring originating from two spawning grounds, with the central site requiring higher migration distance, and hence cost, than the northern site. When accounting for spatially explicit mortality fields, central and northern spawned offspring have about equal survival, as do early and late spawned offspring. Furthermore, central spawned offspring grow faster and are likely to reach a larger size compared with northern spawned offspring. Our results indicate that the fitness benefit of southward migration in the Barents Sea cod is not mainly due to higher early survival of offspring, but rather due to effects of offspring acquiring a larger size.

scholarly journals Microzooplankton Growth Rates Examined across a Temperature Gradient in the Barents Sea

PLoS ONE ◽  
2014 ◽  
Vol 9 (1) ◽  
pp. e86429 ◽  
Author(s):  
Gayantonia Franzè ◽  
Peter J. Lavrentyev
Keyword(s):  
Temperature Gradient ◽  
Growth Rates ◽  
Barents Sea ◽  
The Barents Sea
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