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

scholarly journals Continuous light delays sexual maturation and increases growth of Atlantic cod (Gadus morhua L.) in sea cages

2006 ◽  
Vol 63 (2) ◽  
pp. 365-375 ◽  
Author(s):  
G.L. Taranger ◽  
L. Aardal ◽  
T. Hansen ◽  
O.S. Kjesbu
Keyword(s):  
Sexual Maturation ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Gonad Development ◽  
Somatic Growth ◽  
Continuous Light ◽  
Reproductive Investment ◽  
Spawning Season ◽  
Commercial Fish ◽  
Spawning Period

Abstract Prevention of early sexual maturation is essential in Atlantic cod (Gadus morhua) farming because maturity results in reduced growth, affects flesh quality, and may lead to increased mortality. In farmed cod, almost 100% of the fish mature at two years of age and often at a size of 1.5–2 kg. Two pilot experiments were conducted with cod in sea cages at a commercial fish farm in western Norway (60°N) to test the effect of additional continuous light (LL) on the timing of sexual maturation and somatic growth compared with controls under natural light (NL). In the NL groups, 100% maturation was indicated during the natural spawning period from February to April at the age of two years. By contrast, LL treatment from 27 June (15-month-old cod) or 2 September (18-month-old cod) onwards delayed gonad development by three to five months, reduced reproductive investment, and enhanced winter growth compared with the controls. Fish held at NL decreased in body weight during the spawning season (February–April), whereas LL-exposed fish appeared to continue to grow during their spawning season (May–August). LL-treated cod reached mean body weights of 2.90–3.13 kg within 28 months of hatching, whereas the controls reached 2.20–2.42 kg during the same period.

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.

Photoperiod regulates the timing of sexual maturation, spawning, sex steroid and thyroid hormone profiles in the Atlantic cod (Gadus morhua)

Aquaculture ◽  
2004 ◽  
Vol 229 (1-4) ◽  
pp. 451-467 ◽  
Author(s):  
Birgitta Norberg ◽  
Christopher L. Brown ◽  
Olafur Halldorsson ◽  
Kjetil Stensland ◽  
Björn Thrandur Björnsson
Keyword(s):  
Thyroid Hormone ◽  
Sexual Maturation ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Sex Steroid

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.

Vertical distribution and sexual maturation in cage-farming of Atlantic cod (Gadus morhuaL.) exposed to natural or continuous light

2012 ◽  
Vol 44 (6) ◽  
pp. 903-917 ◽  
Author(s):  
Ole Fredrik Skulstad ◽  
Ørjan Karlsen ◽  
Jan Erik Fosseidengen ◽  
Tore S Kristiansen ◽  
Geir Lasse Taranger ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
Sexual Maturation ◽  
Atlantic Cod ◽  
Continuous Light

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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