Movements of farmed and wild Atlantic cod (Gadus morhua) released in Trinity Bay, Newfoundland

1996 ◽  
Vol 124 (4) ◽  
pp. 619-627 ◽  
Author(s):  
J. S. Wroblewski ◽  
R. K. Smedbol ◽  
C. T. Taggart ◽  
S. V. Goddard
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Trinity Bay

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.

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.

Observations of Adult Atlantic Cod (Gadus morhua) Overwintering in Nearshore Waters of Trinity Bay, Newfoundland

1994 ◽  
Vol 51 (1) ◽  
pp. 142-150 ◽  
Author(s):  
J. S. Wroblewski ◽  
Wade L. Bailey ◽  
Kristine A. Howse
Keyword(s):  
Minimum Distance ◽  
Short Range ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Nearshore Zone ◽  
Island Region ◽  
Northern Cod ◽  
Near Shore ◽  
Surgical Implantation ◽  
Trinity Bay

In the Random Island region of Trinity Bay, Newfoundland, individual adult Atlantic cod (Gadus morhua) with surgically implanted sonic transmitters were repeatedly relocated during the winter of 1990–91. Cod remained near shore, where seawater temperatures were as low as −1.5 °C. These fish did not move in the fall to offshore continental shelf waters as do most northern cod, nor did they move into the deeper waters of Trinity Bay that were slightly warmer than those in the nearshore zone. Of 12 cod released with transmitters in the fall and early winter, two were caught by local inshore fishermen the following spring, providing evidence that adult cod that overwinter nearshore become available to the spring inshore fishery. Another three were caught within a year of release. One fish was hooked in Fortune Bay on the southern coast of Newfoundland, having traveled a minimum distance of 305 nautical miles. These results demonstrate that northern cod can survive the surgical implantation of transmitters for at least a year and that this method is a valid technique for studying the behavior of northern cod. The main limitation to our sonic tracking was the relatively short range of signal reception (<1 nautical mile).

Outcome of an inshore spawning event by northern Atlantic cod (Gadus morhua) at a low stock level

1998 ◽  
Vol 55 (10) ◽  
pp. 2283-2291 ◽  
Author(s):  
R K Smedbol ◽  
D C Schneider ◽  
J S Wroblewski ◽  
D A Methven
Keyword(s):  
Gadus Morhua ◽  
Direct Evidence ◽  
Atlantic Cod ◽  
Spatial Scales ◽  
Spawning Aggregation ◽  
Stock Level ◽  
Egg Density ◽  
Northern Atlantic ◽  
Northeast Coast ◽  
Trinity Bay

A large spawning aggregation of northern Atlantic cod (Gadus morhua) was discovered in a fjord of Trinity Bay, Newfoundland, in April 1995, 3 years after the collapse of this stock and 1 year after the last offshore spawning aggregation was recorded. We hypothesized that spawning by this aggregation would increase the abundance/density of eggs and settled 0-group juveniles above the level of spawning in the bay during recent years. Data from 1995 were compared with ichthyoplankton and postsettlement juvenile surveys conducted in recent years. Egg density was significantly higher in 1995 than the pooled average of two recent years (1991 and 1993). The hypothesized increase in numbers of postsettlement age 0 fish was tested at three different spatial scales: the entire northeast coast of Newfoundland, individual bays, and areas within Trinity Bay. There was no detectable increase in catches of settled age 0 juveniles at any spatial scale. Consequently, while this large spawning aggregation produced locally high egg concentrations, it did not lead to a detectable increase in abundance of newly settled age 0 juveniles in coastal nursery areas. This study did not provide any direct evidence for an increase in recruitment in the inshore region due to the spawning output of locally abundant spawners in Trinity Bay.

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

Responses of Atlantic cod Gadus morhua head kidney leukocytes to phytase produced by gastrointestinal-derived bacteria

2009 ◽  
Vol 36 (4) ◽  
pp. 883-891 ◽  
Author(s):  
Carlo C. Lazado ◽  
Christopher Marlowe A. Caipang ◽  
Sanchala Gallage ◽  
Monica F. Brinchmann ◽  
Viswanath Kiron
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Head Kidney

Some recent data on sperm morphology and motility kinetics in Atlantic cod (Gadus morhua L.)

2021 ◽  
Author(s):  
Sayyed Mohammad Hadi Alavi ◽  
Azadeh Hatef ◽  
Ian A.E. Butts ◽  
Olga Bondarenko ◽  
Jacky Cosson ◽  
...  
Keyword(s):  
Gadus Morhua ◽  
Sperm Morphology ◽  
Atlantic Cod

Natural mortality from poor condition in Atlantic cod (Gadus morhua)

2000 ◽  
Vol 57 (4) ◽  
pp. 826-836 ◽  
Author(s):  
Jean-Denis Dutil ◽  
Yvan Lambert
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Negative Impact ◽  
Fish Muscle ◽  
Early Summer ◽  
Wild Fish ◽  
Natural Mortality ◽  
Muscle Lactate ◽  
Lactate Dehydrogenase Activity ◽  
Poor Condition

The extent of energy depletion was assessed in Atlantic cod (Gadus morhua) in spring and early summer (1993-1995) to assess relationships between poor condition and natural mortality. Several indices of condition were compared in wild fish in the northern Gulf of St. Lawrence and in fish exposed to a prolonged period of starvation in laboratory experiments. Discriminant analyses classified only a small fraction of the wild fish as similar to cod that did not survive and a much larger fraction as similar to cod that survived starvation. This percentage increased from April to May and peaked in June 1993 and 1994. Condition factor and muscle somatic index allowed a clear distinction between live and dead fish. Muscle lactate dehydrogenase activity suggested that cod had experienced a period of negative growth early in 1993, 1994, and 1995. Fish classified as similar to starved individuals were characterized by a higher gonad to liver mass ratio than others. Reproduction may have a negative impact on survival not only in spring but also later into summer, as some individuals were found not to have recovered by late summer. This study shows that natural mortality from poor condition contributed to lower production in the early 1990s.

scholarly journals Gastrointestinal microbial community changes in Atlantic cod (Gadus morhua) exposed to crude oil

2018 ◽  
Vol 18 (1) ◽  
Author(s):  
Andrea Bagi ◽  
Even Sannes Riiser ◽  
Hilde Steine Molland ◽  
Bastiaan Star ◽  
Thomas H. A. Haverkamp ◽  
...  
Keyword(s):  
Microbial Community ◽  
Crude Oil ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Community Changes
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