Overwintering of Adult Northern Atlantic Cod (Gadus morhua) in Cold Inshore Waters as Evidenced by Plasma Antifreeze Glycoprotein Levels

1994 ◽  
Vol 51 (12) ◽  
pp. 2834-2842 ◽  
Author(s):  
Sally V. Goddard ◽  
J. S. Wroblewski ◽  
C. T. Taggart ◽  
K. A. Howse ◽  
W. L. Bailey ◽  
...  
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Antifreeze Glycoproteins ◽  
Cold Temperatures ◽  
Antifreeze Glycoprotein ◽  
Trap Fishery ◽  
In The Wild ◽  
History Of ◽  
Inshore Waters ◽  
Trinity Bay

Adult Atlantic cod (Gadus morhua) are known to produce antifreeze glycoproteins in response to cold temperatures. Our laboratory studies demonstrated that blood plasma levels in adult cod were positively correlated with the number of days they spent in subzero water. Between April 1991 and June 1993, we monitored concentrations of antifreeze glycoproteins in the plasma of late juvenile and adult cod in Trinity Bay, Newfoundland, and used the results to estimate how long cod had been exposed to low water temperatures. A consideration of these data in conjunction with detailed temperature profiles of the area taken over the course of the study allowed us to deduce the distribution of cod in relation to the temperature field. This study provides evidence that (1) blood antifreeze glycoprotein levels can be used to deduce the recent thermal history of cod in the wild and (2) after their inshore summer feeding period, considerable numbers of adult cod overwintered inshore in Trinity Bay in subzero water, producing antifreeze glycoproteins as temperatures fell below 0 °C. From May onwards, "cold-adapted" cod moved into warming surface waters, where they became available to an early inshore trap fishery.

Movements of Atlantic Cod (Gadus Morhua) Within the Spring Thermocline in Trinity Bay, Newfoundland

1995 ◽  
Vol 75 (2) ◽  
pp. 265-284 ◽  
Author(s):  
J.S. Wroblewski ◽  
Sally V. Goddard ◽  
R. Kent Smedbol ◽  
Wade L. Bailey
Keyword(s):  
Surface Waters ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Antifreeze Protein ◽  
Early Spring ◽  
Subzero Temperature ◽  
Cold Adapted ◽  
Protein Levels ◽  
Trap Fishery ◽  
Trinity Bay

Using depth-telemetering, sonic tags orally inserted into the stomachs of Gadus morhua (Pisces: Gadiformes) found over-wintering in Trinity Bay, Newfoundland, the movements of individual fish were observed as surface waters warmed in early spring. Physiological measurements (antifreeze protein levels in the blood) indicate that many cold-adapted, bay cod change their thermal regime at this time. Fish acclimatized to subzero water temperatures enter the newly-formed thermocline and become available to a cod trap fishery. Most sonically-tagged fish resided in 0–1°C waters along the shoreline. Tracking data confirmed indications from declining antifreeze protein levels that cold-adapted cod, having moved into shallow waters in early spring, do not return to deeper, subzero-temperature waters for any appreciable time. At night some cod swam pelagically near the surface. Fish moved at times in the same direction as the tidal current, but ground speeds were several times greater than current velocities. Nocturnal pelagic swimming was also observed during the summer when temperatures within the thermocline exceeded 10°C.

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

Seasonal changes in the plasma levels of glycoprotein antifreeze, Na+, Cl−, and glucose in Newfoundland Atlantic cod (Gadus morhua)

1982 ◽  
Vol 60 (8) ◽  
pp. 1851-1854 ◽  
Author(s):  
G. L. Fletcher ◽  
D. Slaughter ◽  
C. L. Hew
Keyword(s):  
Seasonal Changes ◽  
Gadus Morhua ◽  
Thermal Hysteresis ◽  
Atlantic Cod ◽  
Freezing Point ◽  
Freezing Point Depression ◽  
Antifreeze Glycoproteins ◽  
Glucose Levels ◽  
Total Plasma Protein ◽  
Two Peaks

A seasonal study was carried out on the hematocrits, plasma freezing point depression, and thermal hysteresis, and plasma Na+, Cl−, total protein, and glucose concentrations in laboratory maintained Atlantic cod. Significant thermal hysteresis was evident in the plasma during the months of January to May indicating the presence of antifreeze glycoproteins. Plasma freezing point depression and Na+ and Cl− concentrations were highest during the winter months and lowest during the summer. Two peaks in glucose levels were evident; one in February and the other in July. No seasonal changes were evident in hematocrits and total plasma protein concentrations.

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.

Diel foraging cycles and interactions among juvenile Atlantic cod (Gadus morhua) at a nearshore site in Newfoundland

1998 ◽  
Vol 55 (6) ◽  
pp. 1307-1316 ◽  
Author(s):  
Scott M Grant ◽  
Joseph A Brown
Keyword(s):  
Resource Use ◽  
Zostera Marina ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Prey Size ◽  
Foraging Activity ◽  
Daily Ration ◽  
Behavioural Responses ◽  
In The Wild ◽  
Activity Cycles

In coastal Newfoundland, age 0 Atlantic cod (Gadus morhua) settle in shallow, nearshore regions occupied by older conspecifics. Although intercohort cannibalism is common, little is known of the behavioural responses that limit interactions among juvenile cohorts in the wild. We examined the day-night differences in catch and diet of age 0 and age 1 cod to delineate peak foraging activity and resource use in eelgrass (Zostera marina) habitat. Cod exhibited a size-related shift (age 0 to age 1) from feeding predominantly on zooplankton by day to benthos at night. Intercohort cannibalism occurred when age 1 cod were approximately three times larger than their prey. Concentrations of age 0 cod foraged in the water column during the day, ceased feeding at night, and appeared to disperse to the bottom. Seasonally decreasing daylength and prey size contributed to a decline in daily ration, yet age 0 cod still maintained a strict diurnal foraging cycle. The nocturnal decrease in feeding coincided with an increase in the catch of older conspecifics (age 2 and age 3) and increased foraging activity of age 1 cod, suggesting that avoidance of older conspecifics is an important factor influencing the diel foraging and activity cycles of age 0 cod.

scholarly journals Catch-and-release of Atlantic cod (Gadus morhua): post-release behaviour of acoustically pretagged fish in a natural marine environment

2015 ◽  
Vol 72 (2) ◽  
pp. 252-261 ◽  
Author(s):  
Keno Ferter ◽  
Klaas Hartmann ◽  
Alf Ring Kleiven ◽  
Even Moland ◽  
Esben Moland Olsen
Keyword(s):  
Large Scale ◽  
Gadus Morhua ◽  
Sublethal Effects ◽  
Atlantic Cod ◽  
Small Scale ◽  
Marine Environments ◽  
Vertical Movements ◽  
Catch And Release ◽  
Diel Vertical Migrations ◽  
In The Wild

Studying the sublethal effects of catch-and-release (C&R) is challenging, as there are several potential sources of bias. For example, if behavioural alterations immediately after the release event are to be studied, separation of tagging effects from actual C&R effects is required, which is a challenge in the wild, particularly in marine environments. To investigate the effects of C&R on Atlantic cod (Gadus morhua) in their natural environment, 80 cod were caught in fyke nets, fitted with acoustic transmitters, and released. After recovery from tagging and handling for at least 14 days, nine individuals were recaptured and released at least once during experimental angling, following best release practice. All cod survived the C&R event and did not show any large-scale behavioural changes (i.e., changes in diel vertical migrations). However, analysis of small-scale vertical movements showed that three individuals underwent short-term alterations (e.g., reduced or increased swimming activity). This study showed that pretagging fish with acoustic transmitters before experimental angling is an option when investigating fish behaviour immediately after the release event in marine environments. Moreover, release guidelines for cod should be developed, as cod can recover quickly if caught in shallow waters (<20 m) and properly handled and released.

scholarly journals Evolutionary response to size-selective mortality in an exploited fish population

2007 ◽  
Vol 274 (1613) ◽  
pp. 1015-1022 ◽  
Author(s):  
Douglas P Swain ◽  
Alan F Sinclair ◽  
J Mark Hanson
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Fish Population ◽  
Fish Populations ◽  
Selective Mortality ◽  
Genetic Changes ◽  
Evolutionary Response ◽  
In The Wild ◽  
Size At Age ◽  
Change In Mean

Many collapsed fish populations have failed to recover after a decade or more with little fishing. This may reflect evolutionary change in response to the highly selective mortality imposed by fisheries. Recent experimental work has demonstrated a rapid genetic change in growth rate in response to size-selective harvesting of laboratory fish populations. Here, we use a 30-year time-series of back-calculated lengths-at-age to test for a genetic response to size-selective mortality in the wild in a heavily exploited population of Atlantic cod ( Gadus morhua ). Controlling for the effects of density- and temperature-dependent growth, the change in mean length of 4-year-old cod between offspring and their parental cohorts was positively correlated with the estimated selection differential experienced by the parental cohorts between this age and spawning. This result supports the hypothesis that there have been genetic changes in growth in this population in response to size-selective fishing. Such changes may account for the continued small size-at-age in this population despite good conditions for growth and little fishing for over a decade. This study highlights the need for management regimes that take into account the evolutionary consequences of fishing.

Antifreeze glycoproteins in the plasma of Newfoundland Atlantic cod (Gadus morhua)

1981 ◽  
Vol 59 (11) ◽  
pp. 2186-2192 ◽  
Author(s):  
Choy L. Hew ◽  
Don Slaughter ◽  
Garth L. Fletcher ◽  
Shashikant B. Joshi
Keyword(s):  
Amino Acid ◽  
High Performance ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Antifreeze Proteins ◽  
Gel Filtration ◽  
Exchange Chromatography ◽  
Polar Cod ◽  
Antifreeze Glycoproteins ◽  
Molecular Weights

The plasma of the Atlantic cod, Gadus morhua, contained antifreeze glycoproteins which were present only during the winter months. The antifreeze proteins were isolated, using gel filtration and ion exchange chromatography, and characterized by high performance liquid chromatography. The antifreeze proteins appeared to consist of at least seven components with molecular weights ranging from 2 500 to 33 000. Chemical analysis of the larger components showed a predominance of alanine, threonine, and galactosamine in a ratio of 2:1:1. The smaller peptides contained proline, in addition to alanine and threonine. The amino acid sequence of the smallest glycopeptide (molecular weight 2500) was found to be Ala Ala Thr Pro Ala Thr Ala Ala Thr Pro Ala Thr Ala Ala.These glycoproteins are very similar, if not identical, in amino acid and carbohydrate composition to those isolated from Antaractic nototheniids and several northern gadoids. The sequence of the smallest glycopeptide from the Atlantic cod is identical to that reported for the polar cod, Boreogadus saida.

Interpopulation differences in growth rates and food conversion efficiencies of young Grand Banks and Gulf of Maine Atlantic cod (Gadus morhua)

2000 ◽  
Vol 57 (11) ◽  
pp. 2223-2229 ◽  
Author(s):  
Craig F Purchase ◽  
Joseph A Brown
Keyword(s):  
Growth Rates ◽  
Gadus Morhua ◽  
Gulf Of Maine ◽  
Atlantic Cod ◽  
Larval Fish ◽  
Food Conversion ◽  
Life History Variation ◽  
Grand Banks ◽  
In The Wild ◽  
Conversion Efficiencies

Geographically separated Atlantic cod (Gadus morhua) stocks in the northwest Atlantic exhibit life history variation and have been shown to differ genetically. The genetic and environmental contributions to phenotypic differences, however, have not yet been measured. We used common environment experiments to evaluate the importance of temperature on the observed growth variation between Grand Banks (GB) and Gulf of Maine (GOM) cod stocks. Larvae from the GB grew faster than GOM larvae at both 7 and 12°C. Growth rates of juveniles were not different, but GB juveniles had higher food conversion efficiencies than those from the GOM (at both ambient and warm temperatures). The results indicate that faster growth of GOM cod in the wild is not due to a higher genetic capacity for growth rate in GOM than in GB fish. The findings give evidence of genetically based phenotypic variation, which is in agreement with molecular studies on population differentiation in cod, and support the theory of countergradient variation in growth rates of larval fish.

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