Can simple condition indices be used to monitor and quantify seasonal changes in the energy reserves of cod (Gadus morhua)?

1997 ◽  
Vol 54 (S1) ◽  
pp. 104-112 ◽  
Author(s):  
Y Lambert ◽  
J -D Dutil
Keyword(s):  
Seasonal Changes ◽  
Gadus Morhua ◽  
Simple Condition ◽  
Energy Reserves ◽  
Condition Indices

scholarly journals Deriving condition indices from standard fisheries databases and evaluating their sensitivity to variation in stored energy reserves

2004 ◽  
Vol 61 (10) ◽  
pp. 1900-1917 ◽  
Author(s):  
C Tara Marshall ◽  
Coby L Needle ◽  
Nathalia A Yaragina ◽  
Adnan M Ajiad ◽  
Evgeny Gusev
Keyword(s):  
Body Size ◽  
Gadus Morhua ◽  
Barents Sea ◽  
Condition Index ◽  
Energy Reserves ◽  
Stored Energy ◽  
Stock Level ◽  
Length Relationship ◽  
Condition Indices

To evaluate interstock differences in condition, it would be advantageous to develop stock-level condition indices from standardized databases on weight and length. This study describes a method for estimating stock-level condition when individual-level observations on length and weight are not easily accessible. For each year in a 56-year time series (1946–2001) for Northeast Arctic cod (Gadus morhua), pseudo-observations of weight and length were generated by pairing the Norwegian and Russian values for weight-at-age provided annually to the assessment working group with estimates of length-at-age derived from the same databases. A weight–length relationship fit to each year was then used to predict weight-at-length, i.e., girth, for a range of standard lengths (30–120 cm). This index was uncorrelated with both the liver condition index and the abundance of Barents Sea capelin (Mallotus villosus), suggesting that at the stock level, the girth of cod is not necessarily indicative of the magnitude of stored energy reserves. Partitioning body size into length-at-age and girth revealed long-term trends in body size. In particular, large/old cod showed substantially higher values of both length-at-age and girth that could be the result of long-term increases in fishing mortality.

Seasonal Changes in General Condition and Lipid Content of Cod from Inshore Waters

1967 ◽  
Vol 24 (3) ◽  
pp. 607-612 ◽  
Author(s):  
P. M. Jangaard ◽  
H. Brockerhoff ◽  
R. D. Burgher ◽  
R. J. Hoyle
Keyword(s):  
Seasonal Variation ◽  
Nova Scotia ◽  
Lipid Content ◽  
General Condition ◽  
Seasonal Variations ◽  
Seasonal Changes ◽  
Oil Content ◽  
Gadus Morhua ◽  
Male Fish ◽  
Inshore Waters

The seasonal variations in lipid content and general "condition" of cod, Gadus morhua L., from an inshore population have been determined.Four female and four male fish were chosen from 20 live cod brought in monthly from Terence Bay, Halifax County, Nova Scotia, the fish were pooled and the lipid content determined on the flesh, livers, and gonads. The flesh lipids varied from 0.57% to 0.74% and the oil content of the livers from 15% to 75%.The general "condition" of the fish as expressed by [Formula: see text], the liver condition by [Formula: see text], and the fat content of the liver all showed seasonal variation with maxima in the fall and minima in the spring. KF varied from 0.79 to 1.05 and KL from 1.0 to 4.5. No seasonal variation in the amount of flesh lipids could be detected.

The effects of feeding frequencies on seasonal changes in growth rate and chemical composition of farmed cod (Gadus morhua)

2006 ◽  
Vol 12 (2) ◽  
pp. 157-163 ◽  
Author(s):  
C. SOLBERG ◽  
L. WILLUMSEN ◽  
S. AMBLE ◽  
T. JOHANESSEN ◽  
H. SVEIER
Keyword(s):  
Growth Rate ◽  
Chemical Composition ◽  
Seasonal Changes ◽  
Gadus Morhua

scholarly journals Seasonal cycles in weight and condition in Atlantic cod (Gadus morhua L.) in relation to fisheries

2005 ◽  
Vol 62 (5) ◽  
pp. 1006-1015 ◽  
Author(s):  
L.G.S. Mello ◽  
G.A. Rose
Keyword(s):  
Gadus Morhua ◽  
Physiological Condition ◽  
Atlantic Cod ◽  
Management Strategies ◽  
Maximum Yield ◽  
Product Yield ◽  
Economic Benefits ◽  
Hepatosomatic Index ◽  
Economic Returns ◽  
Condition Indices

Abstract Seasonal cycle in weight and physiological condition of Atlantic cod (Gadus morhua) influenced productivity and economic impacts of the cod fishery in Placentia Bay, Newfoundland. Condition indices (Fulton's K condition factor and hepatosomatic index – HSI) were lowest during the spawning season (spring) and increased rapidly during the postspawning period, reaching maximum values by fall (K and HSI increased on average 24% and 82% between spring and fall, respectively). Somatic weight and condition indices varied seasonally. Condition indices were correlated with an industry index of product yield. Historically, cod fisheries have been prosecuted during all seasons, but simulations of 1997–1999 fisheries indicate that a fall fishery (period of peak physiological condition) resulted in a 8–17% decrease in the number of cod removed from the stock while maintaining the same weight-based quotas, and profiting from maximum yield and better product quality. Spring and summer fisheries resulted in lower yield (6%) and quality (5–26%) of fish products by weight. Seasonal biological cycles could be used as templates for management strategies that promote fisheries conservation and economic benefits by harvesting fish during periods when biological impacts are minimal and economic returns maximal.

scholarly journals Mechanisms regulating oocyte recruitment and skipped spawning in Northeast Arctic cod (Gadus morhua)

2009 ◽  
Vol 66 (9) ◽  
pp. 1582-1596 ◽  
Author(s):  
Jon Egil Skjæraasen ◽  
James Kennedy ◽  
Anders Thorsen ◽  
Merete Fonn ◽  
Bente Njøs Strand ◽  
...  
Keyword(s):  
Egg Production ◽  
Gadus Morhua ◽  
Energy Reserves ◽  
Lower Plasma ◽  
Arctic Cod ◽  
Food Regimes ◽  
Skipped Spawning ◽  
Physical Measurements ◽  
Stock Recruitment ◽  
17Β Estradiol

To examine mechanisms that affect fecundity, atresia, and skipped spawning in Northeast Arctic cod ( Gadus morhua ), we conducted an experiment where wild-caught cod (>60 cm) kept under restricted food regimes were subjected to monthly biopsies and hormonal and physical measurements. The power of body weight as a fecundity proxy increased until the presumed end of follicle proliferation in early November; thereafter, it remained stable. Atresia occurred in most females, but for maturing females, mainly close to spawning. Eighteen percent of the females had small gonads with predominantly previtellogenic oocytes at sacrifice in January. These females were past-spawners, verified by postovulatory follicles in their gonads. These “skippers” had lower condition than maturing cod from December, smaller livers upon sacrifice, and lower plasma 17β-estradiol values from early November. Until November, oocytes developed similarly for all females, but in November, oocyte development was arrested at the early cortical alveoli stage and atresia occurred in all skippers. In summary, fecundity and skipped spawning seem highly influenced by energy reserves during early vitellogenesis and was limited to females only. Finally, skippers were identifiable long before the predicted onset of spawning, which could have implications for forecasting of egg production and hence stock–recruitment relationships.

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.

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