scholarly journals Does the midnight sun increase the feeding rate and hence the growth rate of early juvenile Arcto-Norwegian cod Gadus morhua in the Barents Sea?

2000 ◽  
Vol 197 ◽  
pp. 293-297 ◽  
Author(s):  
K Helle
Keyword(s):  
Growth Rate ◽  
Gadus Morhua ◽  
Feeding Rate ◽  
Barents Sea ◽  
Early Juvenile ◽  
The Barents Sea

scholarly journals Production characteristics of settlements bivalve Mya arenaria Linne, 1758 of the Barents Sea

2021 ◽  
Vol 12 (3-2021) ◽  
pp. 141-150
Author(s):  
O.V. Smolkova ◽  
Keyword(s):  
Growth Rate ◽  
Intertidal Zone ◽  
Linear Growth ◽  
Barents Sea ◽  
Mya Arenaria ◽  
The Barents Sea ◽  
Growth Equations ◽  
Production Characteristics

The linear growth equations and production for bivalve Mya arenaria (Linne, 1758) in the intertidal zone Yarnyshnaya and Zelenetskaya bays of Barents Sea are represented. Our studies have shown that length of the shell Mya reached 26.3–62.5 mm, the highest age was 11 years. Indicators of the growth rate of mollusks from Zelenetskaya Bay are significantly higher than those of mollusks from Yarnyshnaya Bay. Linear growth is described by the Bertalanfi equations: Lt = 84.27 [1–e–0.0721 (t–0.1244)] – for mollusks from Yarnyshnaya Bay, Lt = 118.49 [1–e–0.0566 (t–0.2744)] – for mollusks from Zelenetskaya Bay. Production in the intertidal zone of the Yarnyshnaya Bay was lower (44.8 g/m2 with a biomass of 330 g/m2) than in the intertidal zone of the Zelenetskaya Bay (90.5 g/m2, with a biomass of 258 g/m2). The P/V-value is the coefficient of 0.14 and 0.35, respectively.

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.

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 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.

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