Decreased lipid storage in juvenile Atlantic cod (Gadus morhua) during settlement in cold-water eelgrass habitat

2008 ◽  
Vol 154 (5) ◽  
pp. 823-832 ◽  
Author(s):  
L. A. Copeman ◽  
C. C. Parrish ◽  
R. S. Gregory ◽  
J. S. Wells
Keyword(s):  
Gadus Morhua ◽  
Cold Water ◽  
Atlantic Cod ◽  
Lipid Storage ◽  
Eelgrass Habitat

Thermoregulatory behaviour in cod: Is the thermal preference in free-ranging adult Atlantic cod affected by food abundance?

2019 ◽  
Vol 76 (9) ◽  
pp. 1515-1527 ◽  
Author(s):  
Björn Björnsson
Keyword(s):  
Growth Rate ◽  
Data Storage ◽  
Gadus Morhua ◽  
Cold Water ◽  
Atlantic Cod ◽  
Vertical Mixing ◽  
Metabolic Energy ◽  
Fat Reserves ◽  
Free Ranging ◽  
Thermoregulatory Behaviour

This study supports the hypothesis that well-fed cod (Gadus morhua) seek higher temperatures to increase growth rate, and poorly fed cod select lower temperatures to save metabolic energy. Depth and temperature of free-ranging adult cod (44–79 cm) were studied with data storage tags as part of a ranching project in an Icelandic fjord. Forage fish were regularly provided at four feeding stations where cod formed distinct “herds” (herd cod) that did not mingle much with the rest of the unconditioned cod in the fjord (wild cod). Several parameters (stomach fullness, liver index (fat reserves), condition factor, and growth rate) indicated that food intake was much greater in herd cod than in wild cod. In August, when the thermocline was well established, the herd cod remained in shallow (15–35 m) and warm water (8–10 °C), whereas the wild cod stayed in deep (80–90 m) and cold water (3–4 °C), but occasionally both groups explored depths and temperatures outside their preferred range. After vertical mixing in autumn when thermoregulation was not possible, the depth difference between the two groups decreased significantly.

Temperature and the recruitment of Atlantic cod (Gadus morhua)

1999 ◽  
Vol 56 (11) ◽  
pp. 2069-2077 ◽  
Author(s):  
B Planque ◽  
T Frédou
Keyword(s):  
North Atlantic ◽  
Gadus Morhua ◽  
Cold Water ◽  
Atlantic Cod ◽  
The Other ◽  
Warm Water ◽  
The North ◽  
The North Atlantic ◽  
Interannual Fluctuations ◽  
The Relationship

Variability in the recruitment of fish has been attributed to either changes in the environment or variations in the size of reproductive stocks. Disentangling the effects of environment and stock has proven to be problematic and has resulted in recurrent controversy between studies supporting either hypothesis. In the present study, we examine the relationship between interannual changes in temperature and variation in recruitment for nine Atlantic cod (Gadus morhua) stocks in the North Atlantic. We show that for individual stocks, the relationship often appears weak and statistically not significant. On the other hand, by combining in a single metaanalysis the results from individual stocks, we demonstrate that recruitment of Atlantic cod is linked to interannual fluctuations in temperature in such a way that for stocks located in warm water the relationship is negative, for stocks located in cold water the relationship is positive, and there is no relationship for stocks located in the middle of the temperature range.

Taste Panel Assessment of Cod Fillets After Single and Double Freezing

1966 ◽  
Vol 23 (7) ◽  
pp. 1063-1081 ◽  
Author(s):  
W. A. MacCallum ◽  
E. J. Laishley ◽  
W. J. Dyer ◽  
D. R. Idler
Keyword(s):  
Gadus Morhua ◽  
Cold Water ◽  
Atlantic Cod ◽  
Tap Water ◽  
Poor Quality ◽  
Taste Panel ◽  
Rigor Mortis ◽  
Trap Fishery ◽  
And Storage

Taste panel assessment is reported for Atlantic cod (Gadus morhua) frozen once and twice, and stored at −23 C. The fish were bled, gutted, and iced immediately after capture, and frozen as fillets or dressed fish before, during, and after rigor mortis. Dressed fish were thawed later in recirculated tap water, then processed, refrozen, and stored as fillets. The procedure was conducted three times (June 27, July 19, July 30) during the inshore trap fishery and twice (March and October) during the offshore Grand Bank fishery.For trap-caught landings, the quality of the stored fillets frozen once depended upon the season of catch; for Grand Bank cod, upon the time and place of catching. Trap fish, feeding lightly, caught in cold water in June, were of best quality, grades equalling 70 and over after 20 weeks storage. Those caught on July 30 while feeding heavily in warm water were second; the July 19 fish, obtained under nearly similar conditions, were not significantly poorer than those taken on July 30 and were still acceptable. March landings of Grand Bank fish, once frozen, scored over 70 after 20 weeks storage; October landings only 40 (borderline quality) after 30 weeks. Physiochemical and chemical assessment confirmed the poor quality of the latter.Thawing, refreezing, and storage of June trap fish longer than a few weeks resulted in poor but still acceptable samples. The stored product was soon similar in quality to samples prepared from July landings. In contrast, twice-frozen samples prepared from the March landings from the Grand Bank continued to score high, 70 after 28 weeks storage. Refrozen October samples from the Grand Bank yielded much lower scores, similar to those given the once-frozen samples of the same catch. Thus, in general, an acceptable or better twice-frozen product was obtained by starting with material well handled and quickly chilled, from either the inshore or offshore fishery.

Organization of Microsatellites Differs between Mammals and Cold-water Teleost Fishes

1994 ◽  
Vol 51 (9) ◽  
pp. 1959-1966 ◽  
Author(s):  
Amanda L. Brooker ◽  
Doug Cook ◽  
Paul Bentzen ◽  
Jonathan M. Wright ◽  
Roger W. Doyle
Keyword(s):  
Rainbow Trout ◽  
Gadus Morhua ◽  
Cold Water ◽  
Atlantic Cod ◽  
Pcr Amplification ◽  
Sample Population ◽  
Teleost Fishes ◽  
Dinucleotide Repeats ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Significant Difference

Microsatellites, in particular (dG-dT)n and (dG-dA)n dinucleotide repeats, are abundant and display a high degree of length polymorphism and heterozygosity in eukaryotic genomes. Here, we report the cloning and characterization of 64 microsatellite sequences from Atlantic cod, Gadus morhua. The microsatellites were classified as perfect, imperfect, and compound repeats. The length and integrity of these repeats were compared with microsatellites characterized from two other teleosts, rainbow trout (Oncorhynchus mykiss) and Atlantic salmon (Salmo salar), and from three mammalian genomes, human, porcine, and canine. Differences were found in the proportions of the repeat classes; however, the most significant difference between microsatellites from teleost fishes and mammals was the propensity of the former to be of greater length: some cod and rainbow trout microsatellites were more than twice the size of the longest microsatellite repeats reported for any mammalian genome. Primers for PCR amplification were constructed for seven of the cod microsatellites. Allele frequencies, degree of polymorphism, and heterozygosity were estimated for a sample population. Amplification with these cod primers was also carried out on a number of related gadids. These polymorphic microsatellite loci have enormous potential utility as genetic markers for use in population, breeding, and evolutionary studies.

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.

Growth, condition, and environmental relationships in Atlantic cod (Gadus morhua) in the northern Gulf of St. Lawrence and implications for management strategies in the Northwest Atlantic

1999 ◽  
Vol 56 (10) ◽  
pp. 1818-1831 ◽  
Author(s):  
J -D Dutil ◽  
M Castonguay ◽  
D Gilbert ◽  
D Gascon
Keyword(s):  
Gadus Morhua ◽  
Cold Water ◽  
Atlantic Cod ◽  
Management Strategies ◽  
Extreme Environments ◽  
Eastern Canada ◽  
Intensive Exploitation ◽  
Growth Production ◽  
Marked Decline ◽  
Size At Age

Northern Gulf of St. Lawrence Atlantic cod (Gadus morhua) is one of several stocks that collapsed in eastern Canada following a long period of intensive exploitation. Surplus and net production per capita became nil or negative in the mid-1980s so that any level of exploitation would have caused a decline of the stock. This was partly explained by a marked decline in growth production and is consistent with smaller sizes-at-age but also lower condition factor values during the same period. Correlations between size-at-age and temperature were not significant when corrected for autocorrelation, but slopes were always positive, suggesting higher growth rates at higher temperatures. Smaller sizes-at-age in the 1980s were not associated with changes in the fishery or increased fishing mortality, nor were they consistent with the density-dependence hypothesis. Lengths at age 8 decreased by more than 10 cm as the stock decreased 10-fold in abundance. While size-at-age and temperature covary in cod when all stocks are examined, size-temperature relationships are not as clear if the analysis is restricted to cold-water stocks, possibly because of differences in food availability. Biological production varies from year to year and among stocks and should be taken into consideration when managing fisheries in variable or extreme environments.

Nearshore settlement and localized populations of age 0 Atlantic cod (Gadus morhua) in shallow coastal waters of Newfoundland

1998 ◽  
Vol 55 (6) ◽  
pp. 1317-1327 ◽  
Author(s):  
Scott M Grant ◽  
Joseph A Brown
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Indirect Evidence ◽  
Suitable Habitat ◽  
Site Variation ◽  
Mean And Variance ◽  
Eelgrass Habitat ◽  
The Mean ◽  
Catch Rates ◽  
Density Dependent Habitat Selection

Mark-recapture experiments and seasonal sampling were carried out to examine the nearshore movements, abundance, and behaviour patterns of age 0 Atlantic cod (Gadus morhua) in eelgrass (Zostera marina) and no-eelgrass habitat in Trinity Bay, Newfoundland, during 1994 and 1995. Cod remained localized, not moving further than a few hundred metres in eelgrass and no-eelgrass habitats for several weeks after settling from a pelagic habit, and may remain localized during their first winter. Observations from this study of bulk movements of marked and unmarked cod, high within-site variation in catch rates during the day, and significant day-night differences in the mean and variance of catch data, combined with results from related studies, provide indirect evidence that age 0 cod shoal during the day and disperse at night within the study area. Behaviour patterns exhibited by age 0 cod (restricted nearshore movements, diurnal shoaling, and preference for structurally complex habitat) are mechanisms for predator avoidance, suggesting that predation risk is high in coastal Newfoundland. A significant increase in abundance of age 0 cod in less suitable habitat (no-eelgrass cover) when settlement strength was high is consistent with the hypothesis of density-dependent habitat selection.

Activity and movement patterns of juvenile Atlantic cod, Gadus morhua, in Conception Bay, Newfoundland, as determined by sonic telemetry

1990 ◽  
Vol 68 (7) ◽  
pp. 1434-1442 ◽  
Author(s):  
Donald S. Clark ◽  
John M. Green
Keyword(s):  
Feeding Behaviour ◽  
Gadus Morhua ◽  
Cold Water ◽  
Atlantic Cod ◽  
Activity Patterns ◽  
Energetic Efficiency ◽  
Home Ranges ◽  
Depth Range ◽  
Resting Sites ◽  
Conception Bay

We studied the movements and activity patterns of individual 3-year-old (28–33 cm total length) Atlantic cod, Gadus morhua, in Conception Bay, Newfoundland, using sonic telemetry. Cod tracked between June and early September (summer) were wide ranging (> 3 km/day), nocturnally active, and migrated daily between deep (30 m) cold water where they were inactive and shallow (< 15 m) warm water where they fed. Cod tracked between mid-September and December (autumn) stayed in shallow (< 20 m) water where they were active in relatively small (545.3–2581.6 m2) home ranges during daylight hours and inactive at consistent resting sites at night. Home ranges were over sand whereas resting sites were generally in rocky areas. The seasonal change in migratory behaviour coincided with the disappearance of the shallow (< 30 m) summer thermocline. When the water column became isothermal over the depth range of juvenile cod, they remained in shallow feeding areas throughout the diel period. We suggest that the summer diel migration is a strategy to increase energetic efficiency. Literature on the feeding behaviour of cod and on the predation of juvenile cod suggests that the switch from nocturnal to diurnal activity may be an antipredator strategy. However, more information on the feeding behaviour of cod is required before this hypothesis can be adequately evaluated.

scholarly journals Muscle fibre number varies with haemoglobin phenotype in Atlantic cod as predicted by the optimal fibre number hypothesis

2006 ◽  
Vol 2 (4) ◽  
pp. 590-592 ◽  
Author(s):  
Ian A Johnston ◽  
Marguerite Abercromby ◽  
Øivind Andersen
Keyword(s):  
Metabolic Rate ◽  
Gadus Morhua ◽  
Cold Water ◽  
Atlantic Cod ◽  
Fibre Diameter ◽  
Oxygen Affinity ◽  
Fork Length ◽  
Routine Metabolic Rate ◽  
Muscle Fibres ◽  
Fibre Number

Atlantic cod ( Gadus morhua L.) with the HbI-(2/2) haemoglobin phenotype have a higher blood oxygen affinity at low temperatures and a lower routine metabolic rate than individuals with the HbI-(1/1) phenotype. In the present study, muscle structure was found to be related to haemoglobin phenotype in a coastal population of Atlantic cod from the Saltenfjord region of Northern Norway. The maximum number of fast muscle fibres (FN max ) was reached at approximately 39 cm fork length and was 15% greater in the HbI-(1/1) than in the HbI-(2/2) phenotypes whereas the average fibre diameter for fish of the same fork length was significantly lower. Theoretically, the higher oxygen affinity of the HbI-(2/2) phenotype in the cold water of northern latitudes could have resulted in a relaxation of diffusional constraints at the level of individual muscle fibres, permitting the observed increase in fibre diameter. The results support the optimal fibre number hypothesis which envisages a trade-off between diffusional constraints and the energy cost of maintaining ionic homeostasis with fewer larger diameter muscle fibres in the HbI-(2/2) phenotype contributing to a lower routine metabolic rate.

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