scholarly journals Ecological Effects on Food Utilization, Trypsin Isozymes, and Performance Qualities of Growth and Maturation in Northeast Arctic Cod (Gadus morhua L.)

2012 ◽  
Vol 5 (1) ◽  
pp. 44-56 ◽  
Author(s):  
Krisna Rungruangsak-Torrissen
Keyword(s):  
Gadus Morhua ◽  
Ecological Effects ◽  
Food Utilization ◽  
Arctic Cod ◽  
Trypsin Isozymes ◽  
And Performance

Accuracy and precision in stock separation of north-east Arctic and Norwegian coastal cod by otoliths - comparing readings, image analyses and a genetic method

2005 ◽  
Vol 56 (5) ◽  
pp. 753 ◽  
Author(s):  
Erik Berg ◽  
Tuula H. Sarvas ◽  
Alf Harbitz ◽  
Svein Erik Fevolden ◽  
Arnt Børre Salberg
Keyword(s):  
Visual Inspection ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Complete Separation ◽  
Arctic Cod ◽  
Genetic Method ◽  
North East ◽  
Accuracy And Precision ◽  
Growth Zones ◽  
The Difference

The distinction between north-east Arctic cod and Norwegian coastal cod, two major groups of Atlantic cod (Gadus morhua L.), has for many years been based on different distance and shape similarities between the two first translucent growth zones in the otoliths, subjectively decided by visual inspection in a binocular. To analyse the certainty of this technique, four independent readers have classified 263 cod otoliths in total from five different geographical areas. For three of the readers, between 82% and 89% of the classification results coincided with independent results based on genetic analyses. Further, 38 cod otoliths, where the readers were certain of the classification (21 north-east Arctic cod and 17 coastal cod) were classified by several image analysis methods. A complete separation was obtained by using the ratio of the circumferences of the two zones, providing a typical ratio of approximately 2 for coastal and 1.5 for north-east Arctic cod. The otolith method for separating the two types of cod has been considered adequately accurate in assessing the two stocks of cod. However, the method is sensitive to subjective interpretation, and action needs to be taken to minimise the difference in interpretation among otolith readers.

Biochemical composition and performance of Atlantic cod (Gadus morhua L.) eggs and larvae obtained from farmed and wild broodstocks

Aquaculture ◽  
2012 ◽  
Vol 324-325 ◽  
pp. 267-275 ◽  
Author(s):  
Carlos Frederico Ceccon Lanes ◽  
Teshome Tilahun Bizuayehu ◽  
Sylvie Bolla ◽  
Camila Martins ◽  
Jorge Manuel de Oliveira Fernandes ◽  
...  
Keyword(s):  
Biochemical Composition ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
And Performance ◽  
Eggs And Larvae

scholarly journals External damage to trawl-caught northeast arctic cod (Gadus morhua): Effect of codend design

2019 ◽  
Vol 214 ◽  
pp. 136-147 ◽  
Author(s):  
Guro Møen Tveit ◽  
Manu Sistiaga ◽  
Bent Herrmann ◽  
Jesse Brinkhof
Keyword(s):  
Gadus Morhua ◽  
Arctic Cod ◽  
External Damage

scholarly journals The effect of including length structure in yield-per-recruit estimates for northeast Arctic cod

2007 ◽  
Vol 64 (2) ◽  
pp. 357-368 ◽  
Author(s):  
Cecilie Kvamme ◽  
Bjarte Bogstad
Keyword(s):  
Alternative Model ◽  
Gadus Morhua ◽  
The Other ◽  
Natural Mortality ◽  
Fishing Mortality ◽  
Structured Model ◽  
Arctic Cod ◽  
Traditional Age ◽  
Size At Age ◽  
Yield Per Recruit

Abstract Kvamme, C., and Bogstad, B. 2007. The effect of including length structure in yield-per-recruit estimates for northeast Arctic cod. – ICES Journal of Marine Science, 64: 357–368. For northeast Arctic cod (Gadus morhua), traditional age-based estimates of yield per recruit (YPR) are compared with alternative, though comparable, YPR estimates calculated using an age–length-structured model. In the age–length-structured model, growth, fishing mortality, and natural mortality depend only on length, not on age. This model considers possible changes in size-at-age caused by, for example, a length-selective fishery, and therefore, by comparing the different YPR estimates, the importance of considering the stock's length structure can be evaluated. Length- and weight-at-age of stock and catches were influenced by exploitation pattern and pressure. Such changes are not considered in traditional estimates of YPR, for which weight-at-age is fixed and strictly speaking only representative for the current fishery. Consequently, traditional YPR estimates were somewhat higher than the age–length-based estimates for exploiting smaller fish than at present, and the other way round for exploiting larger fish. Both models indicated a gain in YPR for reducing just exploitation pressure (traditional YPR, 13%; alternative model, 20%) or both reducing exploitation pressure and postponing exploitation (traditional YPR, 23–31%; alternative model, 33–48%), compared with the current fishery.

scholarly journals New encounters in Arctic waters: a comparison of metabolism and performance of polar cod (Boreogadus saida) and Atlantic cod (Gadus morhua) under ocean acidification and warming

Polar Biology ◽  
2016 ◽  
Vol 39 (6) ◽  
pp. 1137-1153 ◽  
Author(s):  
Kristina Lore Kunz ◽  
Stephan Frickenhaus ◽  
Silvia Hardenberg ◽  
Torild Johansen ◽  
Elettra Leo ◽  
...  
Keyword(s):  
Ocean Acidification ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Polar Cod ◽  
Boreogadus Saida ◽  
Polar Cod Boreogadus Saida ◽  
And Performance

scholarly journals Mechanisms regulating oocyte recruitment and skipped spawning in Northeast Arctic cod (Gadus morhua)

2009 ◽  
Vol 66 (9) ◽  
pp. 1582-1596 ◽  
Author(s):  
Jon Egil Skjæraasen ◽  
James Kennedy ◽  
Anders Thorsen ◽  
Merete Fonn ◽  
Bente Njøs Strand ◽  
...  
Keyword(s):  
Egg Production ◽  
Gadus Morhua ◽  
Energy Reserves ◽  
Lower Plasma ◽  
Arctic Cod ◽  
Food Regimes ◽  
Skipped Spawning ◽  
Physical Measurements ◽  
Stock Recruitment ◽  
17Β Estradiol

To examine mechanisms that affect fecundity, atresia, and skipped spawning in Northeast Arctic cod ( Gadus morhua ), we conducted an experiment where wild-caught cod (>60 cm) kept under restricted food regimes were subjected to monthly biopsies and hormonal and physical measurements. The power of body weight as a fecundity proxy increased until the presumed end of follicle proliferation in early November; thereafter, it remained stable. Atresia occurred in most females, but for maturing females, mainly close to spawning. Eighteen percent of the females had small gonads with predominantly previtellogenic oocytes at sacrifice in January. These females were past-spawners, verified by postovulatory follicles in their gonads. These “skippers” had lower condition than maturing cod from December, smaller livers upon sacrifice, and lower plasma 17β-estradiol values from early November. Until November, oocytes developed similarly for all females, but in November, oocyte development was arrested at the early cortical alveoli stage and atresia occurred in all skippers. In summary, fecundity and skipped spawning seem highly influenced by energy reserves during early vitellogenesis and was limited to females only. Finally, skippers were identifiable long before the predicted onset of spawning, which could have implications for forecasting of egg production and hence stock–recruitment relationships.

scholarly journals A framework for making qualities of indicators transparent

2005 ◽  
Vol 62 (3) ◽  
pp. 552-557 ◽  
Author(s):  
Kjellrun Hiis Hauge ◽  
Erik Olsen ◽  
Hilde Elise Heldal ◽  
Hein Rune Skjoldal
Keyword(s):  
Scientific Knowledge ◽  
Harbour Porpoise ◽  
Scientific Advice ◽  
Arctic Cod ◽  
Indicator Value ◽  
Stock Biomass ◽  
Spawning Stock ◽  
Management Context ◽  
And Performance

Abstract A framework is presented to communicate different qualities of and uncertainties in indicators, and to enhance the transparency of conclusions and scientific advice based on them. The framework consists of four parts: Advice Statement, Power of Explanation, Robustness, and Performance Perspectives. The Advice Statement is descriptive and largely quantitative; the last three parts are more analytical and qualitative. Power of Explanation addresses the strength of the associated scientific knowledge. Robustness seeks to clarify how sensitive the indicator value and advice are to underlying assumptions. Performance Perspectives highlight prospects and drawbacks in a management context. The framework and its discussion are illustrated by examples on spawning-stock biomass of Northeast Arctic cod, technetium-99 concentrations in lobster, and harbour porpoise bycatch rates.

Aerobic and anaerobic swimming performance of individual Atlantic cod

2000 ◽  
Vol 203 (2) ◽  
pp. 347-357 ◽  
Author(s):  
S.P. Reidy ◽  
S.R. Kerr ◽  
J.A. Nelson
Keyword(s):  
Individual Variation ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Swimming Performance ◽  
Standard Metabolic Rate ◽  
Endurance Test ◽  
Surface Areas ◽  
And Performance ◽  
The Individual ◽  
Aerobic And Anaerobic

Individual Atlantic cod (Gadus morhua) were exercised using three different measures of swimming performance. (1) An endurance test (critical swimming speed, U(crit), protocol) designed to assess predominantly aerobic endurance swimming (duration hours). (2) An acceleration test (U(burst)), in which the fish were required to swim against a rapidly increasing current until exhausted (duration minutes). This test was designed to assess predominantly glycolytic-based swimming capacity. (3) A sprint test that examined the animals' ability to swim away from a sudden stimulus (duration seconds). Rates of oxygen consumption (mdot (O2)) during the endurance test and various morphological variables of the individual fish were also measured. Both aerobic and anaerobic swimming performance of individual cod were found to be significantly repeatable over a 3 month period. mdot (O2) during the U(crit) protocol was also significantly repeatable at intermediate to high swimming speeds, but not at low speeds. Our results support extrapolation from metabolic rates at incremented swimming speeds to zero activity as the best way to measure standard metabolic rate in cod. While performance in the U(crit) test and the sprint test were positively correlated, there was a negative correlation between performance in the U(crit) test and performance in the U(burst) test. This implies a potential trade-off in individual cod between stamina and the ability to use glycolytic-based locomotion. Inter-individual variation in swimming performance during these protocols, while substantial, was not correlated with individual variation in fin surface areas, age or morphology. However, U(burst) performance was dependent upon the sex of the animals, while performance during the U(crit) protocol was significantly correlated with their aerobic scope for activity.

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