The relationship of embryonic development, mortality, hatching success, and larval quality to normal or abnormal early embryonic cleavage in Atlantic cod, Gadus morhua

Aquaculture ◽  
2009 ◽  
Vol 289 (3-4) ◽  
pp. 265-273 ◽  
Author(s):  
Trevor S. Avery ◽  
Shaun S. Killen ◽  
Tamara R. Hollinger
Keyword(s):  
Embryonic Development ◽  
Gadus Morhua ◽  
Hatching Success ◽  
Atlantic Cod ◽  
Larval Quality ◽  
Embryonic Cleavage ◽  
Relationship Of ◽  
The Relationship

Time series bias in the estimation of density-dependent mortality in stock-recruitment models

1995 ◽  
Vol 52 (1) ◽  
pp. 223-232 ◽  
Author(s):  
Ransom A. Myers ◽  
N. J. Barrowman
Keyword(s):  
Time Series ◽  
Gadus Morhua ◽  
Large Time ◽  
Atlantic Cod ◽  
Model Misspecification ◽  
Parameter Estimates ◽  
Density Dependent Mortality ◽  
Stock Recruitment ◽  
Iteroparous Species ◽  
The Relationship

Large biases can occur in parameter estimates for stock–recruitment models because the stock sizes are not chosen independently, being correlated with variability in recruitment. We examine the importance of this "time series bias" by a comprehensive analysis of available stock–recruitment data and the use of simulations. For semelparous species, i.e., species that reproduce only once, time series bias is important for all populations for which we had data. For iteroparous species, i.e., species that reproduce more than once, large biases occur if the populations are exploited at close to the maximum that is biologically possible. Notably, when there is autocorrelation in natural mortality, for univoltine species, the direction of bias is reversed due to model misspecification. Given moderate sample sizes and moderate levels of exploitation, time series bias is small for species such as Atlantic cod (Gadus morhua), for which α, the slope of the relationship between recruitment and number of spawners as the number of spawners goes to zero, is large. Time series bias will usually be important in species such as hakes (Merluccius) for which α appears to be relatively small.

scholarly journals Relationship of RNA/DNA ratio and temperature to growth in larvae of Atlantic cod Gadus morhua

2003 ◽  
Vol 262 ◽  
pp. 229-240 ◽  
Author(s):  
EM Caldarone ◽  
JM StOnge-Burns ◽  
LJ Buckley
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Relationship Of

Fathers modify thermal reaction norms for hatching success in Atlantic cod, Gadus morhua

2016 ◽  
Vol 474 ◽  
pp. 148-155 ◽  
Author(s):  
F.T. Dahlke ◽  
S.N. Politis ◽  
I.A.E. Butts ◽  
E.A. Trippel ◽  
M.A. Peck
Keyword(s):  
Gadus Morhua ◽  
Hatching Success ◽  
Atlantic Cod ◽  
Thermal Reaction ◽  
Reaction Norms

scholarly journals Mutualistic association of rotifer Philodina roseola with the branchiuran fish ectoparasite Argulus bengalensis at its embryonic stage

2016 ◽  
Vol 12 (3) ◽  
pp. 20151043 ◽  
Author(s):  
Anirban Banerjee ◽  
Soumabrota Poddar ◽  
Subha Manna ◽  
Samar Kumar Saha
Keyword(s):  
Embryonic Development ◽  
Embryonic Stage ◽  
Jelly Coat ◽  
Mechanical Removal ◽  
Service Resource ◽  
Philodina Roseola ◽  
Argulus Bengalensis ◽  
Mutualistic Association ◽  
Relationship Of ◽  
The Relationship

Several rotifers including Philodina spp. are well known to make commensal and parasitic associations with different animals. The present investigation was carried out to decipher the relationship of Philodina roseola with a piscine ectoparasite Argulus bengalensis in its embryonic stage. Mechanical removal of the symbiont P. roseola from the argulid egg strips resulted in the complete (100%) failure in hatching. Several P. roseola individuals were found to feed on the solidified jelly coat of the eggs enabling the larvae to emerge under both laboratory and field conditions. Under the laboratory condition, the experimental removal of P. roseola did not affect the embryonic development, but it rendered the jelly coat intact; therefore, the larvae were unable to make hatching furrow and subsequently died. The results of our experiments thus prove this service–resource relationship to be a mutualism. Although the association is facultative for P. roseola , it is obligatory for Argulus spp. An act of intervention in this relationship thus offers a promising control of argulosis.

Early embryonic cleavage pattern, hatching success, and egg-lipid fatty acid composition: comparison between two cod (Gadus morhua) stocks

1997 ◽  
Vol 54 (10) ◽  
pp. 2410-2416 ◽  
Author(s):  
J Pickova ◽  
P C Dutta ◽  
P -O Larsson ◽  
A Kiessling
Keyword(s):  
Gadus Morhua ◽  
Hatching Success ◽  
Hatching Rate ◽  
Cleavage Pattern ◽  
Egg Viability ◽  
Lipid Fatty Acid ◽  
Embryonic Cleavage ◽  
The Baltic ◽  
Lipid Fatty Acid Composition ◽  
Baltic Cod

Baltic cod (Gadus morhua), from a brackish environment, were compared with oceanic (Skagerrak) cod in terms of early embryonic cleavage pattern, hatching success, and egg-lipid fatty acid composition. The influence of diet on these variables was investigated by analysing eggs from the Baltic stock, caught during three successive years and given controlled food for 24, 7, and 2 months, respectively, before the experiment commenced. Skagerrak cod eggs contained twice as much arachidonic acid (AA) in the phospholipid (PL) fraction as eggs from the Baltic cod, regardless of the length of time the Baltic cod had been kept in captivity and fed a control diet. Correlation between hatching rate and docosahexaenoic (DHA; 22:6n-3)/ eicosapentaenoic acid (EPA; 20:5n-3) ratio was significant (r2 = 0.56) as well as hatching rate and AA content of the PL fraction (r2 = 0.61). Symmetry during development, which was correlated to egg viability, was higher for eggs from Skagerrak than those from the Baltic stock. We suggest that AA content and DHA/EPA ratio of the PL fraction are important factors influencing egg viability and possibly also egg symmetry.\b Further, it appears that the factor(s) influencing the composition of the PL fraction is mostly related to stock rather than to diet.

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.

Larval Fish Age, Growth, and Body Shrinkage: Information Available from Otoliths

1989 ◽  
Vol 46 (11) ◽  
pp. 1884-1894 ◽  
Author(s):  
Richard L. Radtke
Keyword(s):  
Growth Rate ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Larval Fish ◽  
Quadratic Function ◽  
Age And Growth ◽  
Fish Length ◽  
Elapsed Time ◽  
Developmental Rates ◽  
The Relationship

External and internal examination of Atlantic cod (Gadus morhua) otoliths for macrostructure and microstructure, by light and scanning electron microscopy, indicated daily rhythmic patterns. The first daily increment developed the day after hatching. Sagittae changed shape from spherical to oblong at 20 d and to crenulated at 50−60 d old. Cod were reared at three temperatures (6,8 and 10 °C), to provide a range of growth and developmental rates. Distinctive marks formed at yolk-sac absorption, initiation of feeding and settlement. It was possible to determine age and growth rate from otolith analyses. The relationship between otolith length and fish size was independent of growth rate; it followed a quadratic function for the smaller individuals (< 6.5 mm), and it was linear in individuals greater than 25 mm. Larval fish shrank considerably at death. The magnitude of shrinkage was dependent on larval length, and the elapsed time between death and fixation. Immediate fixation in ethanol resulted in minimal shrinkage. The relationship between fish length and otolith diameter may be used to correct for shrinkage associated with collection and death.

Effect of foraging activity on the shoal structure of cod (Gadus morhua)

1995 ◽  
Vol 52 (11) ◽  
pp. 2377-2387 ◽  
Author(s):  
E. M. DeBlois ◽  
G. A. Rose
Keyword(s):  
Gadus Morhua ◽  
Critical Level ◽  
Atlantic Cod ◽  
Horizontal Displacement ◽  
Foraging Activity ◽  
Laboratory Findings ◽  
Acoustic Methods ◽  
Theoretical Predictions ◽  
Shrimp Density ◽  
The Relationship

Acoustic methods used to quantify the shoaling dynamics of Atlantic cod (Gadus morhua) during their shoreward migration across the northeast Newfoundland shelf (spring 1992) showed that shoal structure and horizontal displacement were associated with the density distribution of small pelagic scatterers, for example, shrimp (Pandalus borealis). Cod speeds (to 20 km/d) were lower after encounters with shrimp (4–7 km/d). The relationship between several characteristics of the cod shoal (density, vertical spread, height off the bottom) and shrimp density was dome shaped. Internal shoal densities declined and shoal spread and height increased until shrimp densities surpassed a critical level. Above this threshold, these trends were reversed. The vertical spread of the cod shoal matched that of shrimp up to, but not beyond, a shrimp spread of 85 m. At this observed maximum in the expansion of the shoal, fish were eight body lengths apart. At all times during our survey, cod stayed within the warmer waters (> 2 °C) found at depths greater than 250 m. Our results are the first field verification of theoretical predictions and laboratory findings that shoals expand and contract in response to foraging activity and demonstrate the potential importance of cod aggregation dynamics to interpretations of trawl data.

Cardiac output as a predictor of metabolic rate in cod gadus morhua

1998 ◽  
Vol 201 (19) ◽  
pp. 2779-2789 ◽  
Author(s):  
DM Webber ◽  
RG Boutilier ◽  
SR Kerr
Keyword(s):  
Cardiac Output ◽  
Oxygen Consumption ◽  
Metabolic Rate ◽  
Swimming Speed ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Rate Of Oxygen Consumption ◽  
Free Ranging ◽  
The Relationship ◽  
Fisheries Biology

Adult Atlantic cod (2 kg Gadus morhua) were fitted with Doppler ultrasonic flow-probes to measure ventral aortic outflow (i.e. cardiac output). The probes remained patent for upwards of 3 months, during which time detailed relationships between cardiac output (), heart rate (fh) and rate of oxygen consumption (O2) were determined as a function of swimming speed and temperature (5 degreesC and 10 degreesC). The rate of oxygen consumption increased linearly with and exponentially with swimming speed. A very good correlation was observed between O2 and (r2=0.86) compared with the correlation between O2 and fh (r2=0.50 for all 10 degreesC data and r2=0.86 for all 5 degreesC data). However, the O2 versus fh correlation gradually improved over approximately 1 week after surgery (r2=0.86). The relationship between O2 and was independent of temperature, while the relationship between O2 and fh changed with temperature. Hence, calculating O2 from is simpler and does not require that temperature be recorded simultaneously. Variations in cardiac output were determined more by changes in stroke volume (Vs) than by fh; therefore, fh was a less reliable predictor of metabolic rate than was . Given that can be used to estimate O2 so faithfully, the advent of a cardiac output telemeter would enable robust estimates to be made of the activity metabolism of free-ranging fish in nature, thereby strengthening one of the weakest links in the bioenergetic models of fisheries biology.

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