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.

Seasonal variation in temperature preference of juvenile Atlantic cod (Gadus morhua), with evidence supporting an energetic basis for their diel vertical migration

1991 ◽  
Vol 69 (5) ◽  
pp. 1302-1307 ◽  
Author(s):  
Donald S. Clark ◽  
John M. Green
Keyword(s):  
Seasonal Variation ◽  
Vertical Migration ◽  
Diel Vertical Migration ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Energetic Efficiency ◽  
Temperature Preference ◽  
Ambient Temperatures ◽  
Inshore Waters ◽  
Conception Bay

Juvenile (3-year-old) Atlantic cod (Gadus morhua) from Broad Cove, Conception Bay, Newfoundland, exhibit seasonal variation in temperature preference. Laboratory studies show that juvenile cod from ambient temperature water prefer temperatures that correlate closely with seasonal changes in the temperature of the inshore waters that they inhabit. A similar pattern is shown by fish held in 10 °C water over winter, indicating that variation in temperature preference is not simply a response to changing ambient temperatures but occurs in an anticipatory manner that allows them to maintain their physiologically optimal temperature at a seasonally appropriate level. The results also support the hypothesis that the diel vertical migration of juvenile cod in summer increases energetic efficiency by reducing metabolic costs in nonfeeding hours.

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.

Depth-dependent variation in condition and length-at-age of Atlantic cod (Gadus morhua) in the southern Gulf of St. Lawrence

2002 ◽  
Vol 59 (9) ◽  
pp. 1451-1459 ◽  
Author(s):  
G A Chouinard ◽  
D P Swain
Keyword(s):  
Deep Water ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
High Abundance ◽  
Shallow Waters ◽  
Depth Range ◽  
Deep Waters ◽  
Feeding Grounds

We describe depth-dependent variation in the condition and length-at-age of southern Gulf of St. Lawrence cod (Gadus morhua) on their feeding grounds in September 1971–2000. Bathymetric variation in condition appears to be linked to abundance. In periods of low abundance, condition was relatively uniform over shallow and intermediate depths (<100–125 m). During periods of high abundance, condition was highest in the shallowest waters and declined steadily as depth increased to 100 m. In all periods, condition was low in deep water. Bathymetric trends in length-at-age contrasted with those in condition. Length-at-age was high in the deep waters where condition was low. Length-at-age also tended to increase from minimum values at intermediate depths to high values in shallow waters. This tendency was most striking in the 1990s, a period when condition was uniform over this depth range. We discuss the ecological, bioenergetic, and sampling implications of these patterns.

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

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.

Potential methods for measuring the activity patterns and energy use of Atlantic cod (Gadus morhua)

2009 ◽  
Vol 66 (7) ◽  
pp. 1095-1106 ◽  
Author(s):  
Matthew J. Gollock ◽  
Kristopher J. Hunter ◽  
Douglas A. Syme ◽  
Marcus Freeman ◽  
R. Scott McKinley ◽  
...  
Keyword(s):  
Swimming Speed ◽  
Gadus Morhua ◽  
Energy Use ◽  
Atlantic Cod ◽  
Activity Patterns ◽  
Strong Relationship ◽  
Marine Species ◽  
Free Swimming ◽  
Cost Of Transport ◽  
Wide Range

As there are no commercially available acoustic telemetry devices for quantifying the swimming activity and activity-related metabolic expenditures of a wide range of marine species, we (i) examined the suitability of three methods (electromyography; sonomicrometry; and tail differential pressure tags (DPT)) for measuring the swimming speed of Atlantic cod ( Gadus morhua ), and indirectly, metabolic rate (MO2) and (ii) measured the activity pattern of free-swimming cod carrying the DPT. All three methods yielded significant relationships with swim speed during a critical swimming speed (Ucrit) test. However, only the DPT was able to discern between swimming speed differences of 0.1 body lengths (BL)·s–1 and provide a strong relationship with MO2. Further, we found that free-swimming cod fitted with the DPT swam at an average speed of 0.33 BL·s–1, the speed previously reported to result in minimal cost of transport for this species. While the DPT has considerable potential for assessing the bioenergetics of marine fishes, the swimming economy of tagged Atlantic cod was lower above 0.4 BL·s–1 as compared with untagged fish, and Ucrit was reduced by 25%. These latter effects are likely related to the tag’s present size (39 g) and design.

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.

Sign in / Sign up

Export Citation Format

Share Document