Interaction between temperature and photoperiod on growth and feeding of Atlantic cod (Gadus morhua): possible secondary effects

2007 ◽  
Vol 64 (2) ◽  
pp. 239-248 ◽  
Author(s):  
Albert Kjartansson Imsland ◽  
Atle Foss ◽  
Thomas Alvseike ◽  
Arild Folkvord ◽  
Sigurd Olav Stefansson ◽  
...  
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Physiological Mechanism ◽  
Continuous Light ◽  
Day Length ◽  
Ambient Conditions ◽  
Feed Conversion ◽  
Natural Photoperiod ◽  
Extended Day ◽  
Laboratory Trial

Interactions between temperature and photoperiod on growth of Atlantic cod (Gadus morhua) juveniles (initial weight 9.1 g) were studied by rearing juvenile cod 3 months under simulated natural photoperiod (LDN) and continuous light (LD24:0) at 7, 10, and 13 °C. Juvenile Atlantic cod exposed to LD24:0 had higher growth rate and better feed conversion efficiency compared with cod reared under LDN. Optimal temperature for growth of juvenile Atlantic cod in the size range 5–50 g was influenced by photoperiod and was estimated to be 12.3 °C under LD24:0 and 15.7 °C under LDN. After termination of the laboratory study, the fish were reared in sea pens at ambient conditions for 17 months. The growth-enhancing effect of LD24:0 could be traced far beyond the duration of the laboratory trial, as the final mean weights in June 2005 of the fish reared at LD24:0 and 13 and 10 °C in the laboratory trial were 8% and 13% higher than those of the respective LDN groups. Our study indicates a physiological mechanism that might be linked to cod migrations, as maximal growth and feeding efficiency will be attained in areas during a season with extended day length or continuous light.

Seasonal Variation in the Physiological Response of Atlantic Cod (Gadus morhua) to Low Salinity

1992 ◽  
Vol 49 (6) ◽  
pp. 1149-1156 ◽  
Author(s):  
J.-D. Dutil ◽  
J. Munro ◽  
C. Audet ◽  
M. Besner
Keyword(s):  
Skeletal Muscle ◽  
Seasonal Variation ◽  
Osmotic Pressure ◽  
Principal Components ◽  
Physiological Response ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Low Salinity ◽  
Natural Photoperiod ◽  
Highly Correlated

Plasma Na+, Cl−, K+, osmotic pressure, Cortisol, glucose, and protein, blood hemoglobin and hematocrit, and water content of skeletal muscle were measured at regular intervals during a 28-d period following the transfer of Atlantic cod (Gadus morhua) to waters of 7, 14, 21, and 28‰ (control) salinity. These experiments were repeated four times at 3-mo intervals under natural photoperiod and temperatures (0–10 °C). Exposure to 7‰ salinity caused large decreases in plasma Na+ in winter (25 mmol/L over 14 d) and in spring (32 mmol/L over 7 d) when the lowest value for the year was reached (156 mmol/L). Transfer to 14 and 21‰ salinity resulted in a slight decrease (maximum 4%) in plasma Na+ which was much smaller than the seasonal variation (14%) observed in controls. Hydration of skeletal muscle occurred only at 7‰ (2.3% maximum), but these changes were small compared with the seasonal variation (3.9%) observed in the controls. Principal components and clustering analyses showed that all ionic and osmotic variables measured were highly correlated while being only weakly associated with the condition or reproductive status of the fish. There were no indications that acclimation to low salinity was stressful for cod.

scholarly journals The effect of alternate‐day feeding on growth and feed conversion in Atlantic cod Gadus morhua

2021 ◽  
Author(s):  
Marit Bjørnevik ◽  
Albert K. D. Imsland ◽  
Henriette Hanssen ◽  
Bjørn Roth ◽  
Erik Vikingstad ◽  
...  
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Feed Conversion

scholarly journals Towards cod without spawning: artificial continuous light in submerged sea-cages maintains growth and delays sexual maturation for farmed Atlantic cod Gadus morhua

2013 ◽  
Vol 3 (3) ◽  
pp. 245-255 ◽  
Author(s):  
ØJ Korsøen ◽  
T Dempster ◽  
JE Fosseidengen ◽  
Ø Karlsen ◽  
F Oppedal ◽  
...  
Keyword(s):  
Sexual Maturation ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Continuous Light

The role of seasonally altering photoperiod in regulating physiology in Atlantic cod (Gadus morhua). Part I. Sexual maturation

2007 ◽  
Vol 64 (1) ◽  
pp. 84-97 ◽  
Author(s):  
Andrew Davie ◽  
Mark JR Porter ◽  
Niall R Bromage ◽  
Herve Migaud
Keyword(s):  
Sexual Maturation ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Reproductive Activity ◽  
Continuous Illumination ◽  
Natural Photoperiod ◽  
Artificial Photoperiod ◽  
Commercially Important ◽  
Photoperiod Manipulation

While the Atlantic cod (Gadus morhua) displays clear seasonality in its reproductive cycle, the exact photic signal that entrains this rhythm is yet undefined. This present work developed a model to describe the photic regulation of reproduction in the species in comparison with other commercially important temperate teleosts. This was achieved through the strategic masking of the natural photoperiod cycle during the first 2 years of life with the application of continuous illumination. The results demonstrated that it is the falling autumnal photoperiod signal after the summer solstice, more specifically after October, that is responsible for recruiting individuals to enter the sexual maturation cycle. Furthermore, in all treatments where this signal was masked through the application of continuous illumination, there was no significant reproductive activity and growth was improved by up to 60% at 27 months posthatch. This information is of particular value to the developing cod aquaculture industry in which the management of reproduction using artificial photoperiod manipulation will be of vital economic importance.

Low temperature regulation of antifreeze glycopeptide levels in Atlantic cod (Gadus morhua)

1987 ◽  
Vol 65 (2) ◽  
pp. 227-233 ◽  
Author(s):  
Garth L. Fletcher ◽  
Madonna J. King ◽  
Ming H. Kao
Keyword(s):  
Low Temperature ◽  
Gadus Morhua ◽  
Cold Water ◽  
Atlantic Cod ◽  
Continuous Light ◽  
Half Time ◽  
Antifreeze Glycoproteins ◽  
Long Day ◽  
Biological Half Time ◽  
Influence Of Water

The influence of water temperature and photoperiod on the timing of the annual cycle of plasma antifreeze glycoproteins (AFGP) was examined in Atlantic cod. Long day lengths (18 h) or continuous light had no effect on the time of appearance or disappearance of AFGP from the plasma. Cold water (0 °C) advanced the time of AFGP appearance by as much as 100 days. Long day lengths had no effect on this early induction of AFGP production. AFGP was not detectable in the plasma of fish exposed to water temperatures greater than 1 °C. Although small amounts of AFGP did appear in the plasma of cod exposed to 1 °C, it immediately began to disappear while plasma levels in normal and 0 °C acclimated cod continued to rise. The biological half time of AFGP activity was very sensitive to temperature, ranging from 15.6 days at 5 °C to 99.4 days at 0 °C. The results of this study suggest that the appearance of AFGP in cod during the winter months is dependent on the cod's exposure to water temperatures at least as low as 1 °C. Although 1 °C appears to be capable of initiating production of AFGP, it is not low enough to allow normal protective levels to be built up in the plasma.

scholarly journals Effects of photoperiod and exercise on growth, liver size, and age at puberty in farmed Atlantic cod (Gadus morhua L.)

2006 ◽  
Vol 63 (2) ◽  
pp. 355-364 ◽  
Author(s):  
Ø. Karlsen ◽  
B. Norberg ◽  
O.S. Kjesbu ◽  
G.L. Taranger
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Continuous Light ◽  
Gonadal Development ◽  
Natural Light ◽  
Food Conversion ◽  
Liver Size ◽  
Time Required ◽  
Loss Of Appetite ◽  
Food Conversion Efficiency

Abstract Sexual maturation in Atlantic cod (Gadus morhua) results in loss of appetite and weight during spawning, leads to increased production time required to reach desired harvest size, and results in greater mortality and reduced food conversion efficiency. Thus, methods to stop or delay maturation are urgently needed. In the present study, the effect of continuous light (LL) treatment on maturation was tested in combination with different exercise levels in seawater tanks compared with controls under natural light. LL treatment in lightproof tanks arrested gonadal development for at least 8 months. Exercising Atlantic cod by forcing them to swim with 0, 0.5, or 1 body length per second from the summer solstice had no effect on incidence of maturation either under natural light or under LL. Growth was enhanced in the LL groups compared with the NL groups, mainly as a result of the weight loss of the NL groups during spawning.

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