scholarly journals Differences in spawning time of captive Atlantic cod from four regions of Norway, kept under identical conditions

2006 ◽  
Vol 63 (2) ◽  
pp. 216-223 ◽  
Author(s):  
Håkon Otterå ◽  
Ann-Lisbeth Agnalt ◽  
Knut E. Jørstad
Keyword(s):  
Life History ◽  
Genetic Control ◽  
Environmental Conditions ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Spawning Period ◽  
Life History Parameters ◽  
Wide Range ◽  
Spawning Time ◽  
The Difference

Abstract Several hundred Atlantic cod (Gadus morhua L.) were collected from selected spawning grounds along the Norwegian coast in March 2002. Four areas or regions that represent a wide range of environmental conditions were chosen for our breeding experiments: Porsangerfjord, Tysfjord, Helgeland, and Øygarden. Cod were transported to Øygarden near Bergen, individually tagged, and kept in sea cages. In both 2003 and 2004, a total of 40 family groups (adult pairs) representing the four regions were monitored for their spawning performance in separate tanks. During the spawning period, the quantity and diameter of eggs were recorded. During 2003, the time of peak spawning differed among groups. It was evident that the broodstock from the Øygarden region spawned about one month earlier than the broodstock collected from the Helgeland region. This also occurred in 2004, two years after the cod were collected, suggesting that the difference has a genetic component. Differences in life history parameters between cod populations, such as spawning cycles as described here, could be adaptive and under genetic control. This must be taken into consideration when assessing precautionary means of overcoming the problem with escapees from future cod mariculture.

Effects of temperature on life history set the sensitivity to fishing in Atlantic cod Gadus morhua

2014 ◽  
Vol 514 ◽  
pp. 217-229 ◽  
Author(s):  
HY Wang ◽  
LW Botsford ◽  
JW White ◽  
MJ Fogarty ◽  
F Juanes ◽  
...  
Keyword(s):  
Life History ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Effects Of Temperature

Spawning behaviour of Atlantic cod, Gadus morhua: evidence of mate competition and mate choice in a broadcast spawner

1999 ◽  
Vol 56 (1) ◽  
pp. 97-104 ◽  
Author(s):  
Jeffrey A Hutchings ◽  
Todd D Bishop ◽  
Carolyn R McGregor-Shaw
Keyword(s):  
Mate Choice ◽  
Gadus Morhua ◽  
Dna Analysis ◽  
Atlantic Cod ◽  
Multiple Paternity ◽  
Reproductive Behaviour ◽  
Male Dominance ◽  
Male Body ◽  
Experimental Conditions ◽  
Spawning Period

We quantified individual differences in Atlantic cod, Gadus morhua, reproductive behaviour at a field-reported spawning density under experimental conditions. Marked individuals (nine females, seven males) were observed twice daily and videotaped continuously for 9 weeks at ambient photoperiod and temperature in a large tank (60 m3). Agonistic interactions appeared to maintain a size-based dominance hierarchy among males. Multiple paternity per spawning bout, revealed by microsatellite DNA analysis, suggested a link between dominance and fertilization success. Interactions between sexes were dominated by the circling of females by males. Predicated by vertical separation from males, and after descending to the bottom, a motionless female would be circled up to 17 times, often by one male per circling bout but by several males throughout the spawning period. Although circling frequency increased with male dominance and male body size, initiation and termination of this behaviour appeared to be under female control. Circling provides opportunities for males to gain individual access to reproductive females and for females to assess the quality of potential mates. Our evidence for nonrandom mate choice and for male-male competition and display has implications for Atlantic cod mating systems and effects of fishing on their reproductive success.

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.

scholarly journals Regional changes in vertebra morphology during ontogeny reflect the life history of Atlantic cod (Gadus morhua L.)

2013 ◽  
Vol 222 (6) ◽  
pp. 615-624 ◽  
Author(s):  
Per G. Fjelldal ◽  
Geir K. Totland ◽  
Tom Hansen ◽  
Harald Kryvi ◽  
Xiyuan Wang ◽  
...  
Keyword(s):  
Life History ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
History Of

The influence of maternal effects in larval survival on fishery harvest reference points for two life-history patterns

2014 ◽  
Vol 71 (1) ◽  
pp. 151-161 ◽  
Author(s):  
Paul D. Spencer ◽  
Sarah B.M. Kraak ◽  
Edward A. Trippel
Keyword(s):  
Life History ◽  
Pacific Ocean ◽  
Maternal Effects ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Larval Survival ◽  
Reference Points ◽  
Life History Pattern ◽  
Gadus Macrocephalus ◽  
Potential Interactions

Increased larval viability with increased spawner age (i.e., maternal effects) have been observed in Atlantic cod (Gadus morhua) and Pacific rockfish (Sebastes spp.) stocks. Analytical results from a Beverton–Holt recruitment model indicate density-independent maternal effects affected the relative stock productivity and fishing rate reference points. We simulated populations based on Pacific cod (Gadus macrocephalus) and Pacific ocean perch (Sebastes alutus) to explore how estimates of reference points Fmsy and Fcrash are affected by maternal effects and potential interactions with life-history pattern, recruitment autocorrelation, and exploitation rate. Estimates of Fmsy and Fcrash were made from populations with maternal effects using either total larvae (proportional to eggs) or viable larvae (incorporating the maternal effect). Maternal effects have the largest impact upon estimated population productivity at high fishing rates. Estimates of Fmsy and Fcrash for cod were also affected by autocorrelated recruitment variability because of their reduced longevity compared with Pacific ocean perch. These results suggest the importance of evaluating the influence of maternal effects on estimated stock productivity on a case-by-case basis, particularly for depleted stocks composed of relatively young spawners.

Studies on the Life-History of the Ascarid Porrocaecum decipiens in the Bras d'Or Lakes, Nova Scotia, Canada

1960 ◽  
Vol 17 (6) ◽  
pp. 763-774 ◽  
Author(s):  
D. M. Scott ◽  
W. F. Black
Keyword(s):  
Life History ◽  
Nova Scotia ◽  
Intermediate Host ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Phoca Vitulina ◽  
Halichoerus Grypus ◽  
Grey Seal ◽  
Important Food ◽  
History Of

Larvae of the parasitic ascarid (Porrocaecum decipiens) occurred commonly in the musculature and viscera of Atlantic cod (Gadus morhua) in the Bras d'Or Lakes. They were also present in the musculature of nine other species of teleosts and probably also in the viscera of skates (Raja sp.). Most larvae were longer than 20 mm. None was shorter than 10 mm, a fact which suggested the existence of some earlier intermediate host, probably an invertebrate. More than 8,000 mysids, an important food of fishes when they first become infected, were examined for nematodes. Although 110 nematodes were found, only one certainly and four dubiously appeared to be Porrocaecum. The definitive hosts were the harbour seal (Phoca vitulina) and the grey seal (Halichoerus grypus). The distribution of seals coincided with local variations in the incidence of the parasite in cod.

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