Relationships Between RNA–DNA Ratio, Prey Density, and Growth Rate in Atlantic Cod (Gadus morhua) Larvae

1979 ◽  
Vol 36 (12) ◽  
pp. 1497-1502 ◽  
Author(s):  
L. J. Buckley
Keyword(s):  
Growth Rate ◽  
Nutritional Status ◽  
Growth Rates ◽  
Prey Density ◽  
Gadus Morhua ◽  
Slow Growth ◽  
Atlantic Cod ◽  
Larval Fish ◽  
Dry Weight ◽  
Dna And Rna

The protein, DNA, and RNA content of larvae maintained at 1.0 plankter/mL increased at the rates of 9.3, 9.9, and 9.8% per day, respectively, for the 5 wk after hatching. Protein reserves of larvae held at 0 or 0.2 plankters/mL were depleted by 45 and 35%, respectively, prior to death 12–13 d after hatching. Starved larvae had similar protein concentrations (percent of dry weight), lower RNA concentrations, and higher DNA concentrations than fed larvae. Larvae held at higher plankton densities had higher RNA–DNA ratios and faster growth rates than larvae held at lower plankton densities. The RNA–DNA ratio was significantly correlated (P < 0.01) with the protein growth rate. The RNA–DNA ratio appears to be a useful index of nutritional status in larval Atlantic cod (Gadus morhua) and may be useful for determining if cod larvae were in a period of rapid or slow growth at the time of capture. Key words: RNA–DNA ratio, starvation, protein, nucleic acids, growth, larval fish, Atlantic cod

Effects of Intermediate and Low Salinity Conditions on Growth Rate and Food Conversion of Atlantic Cod (Gadus morhua)

1994 ◽  
Vol 51 (7) ◽  
pp. 1569-1576 ◽  
Author(s):  
Yvan Lambert ◽  
Jean-Denis Dutil ◽  
Jean Munro
Keyword(s):  
Growth Rate ◽  
Food Intake ◽  
Growth Rates ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Food Conversion ◽  
Coastal Regions ◽  
Low Salinity ◽  
Feeding Regimes ◽  
Food Conversion Efficiency

Growth rates of Atlantic cod (Gadus morhua) were measured under different salinity conditions to test the hypothesis that growth would be best in an isosmotic environment. The results of two experiments (spring and autumn 1991) conducted at three different salinities (7, 14, and 28‰) and two feeding regimes indicate a significant effect of salinity and ration on growth rate. Within each experiment, growth rates were highest for cod maintained in intermediate salinity conditions (14‰). Growth rates in low salinity conditions (7‰) were higher than in seawater (28‰) during the spring, but during the autumn, growth rates of cod held under low salinity conditions and in seawater were similar. Higher growth rates at lower salinities resulted from an increase in food conversion efficiency. They were not associated with an increase in food intake, changes in composition (proteins, lipids, or water), or relative allocation of energy to the tissues (muscle, liver, and gonads) of cod. The results indicate that rearing cod at intermediate salinities, such as would occur in estuaries or coastal regions, could confer an advantage for cod aquaculture.

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.

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.

Modelling feeding, growth, and habitat selection in larval Atlantic cod (Gadus morhua): observations and model predictions in a macrocosm environment

2007 ◽  
Vol 64 (1) ◽  
pp. 136-151 ◽  
Author(s):  
Trond Kristiansen ◽  
Øyvind Fiksen ◽  
Arild Folkvord
Keyword(s):  
Habitat Selection ◽  
Growth Rates ◽  
Prey Density ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Food Limitation ◽  
Limited Growth ◽  
Individual Parameter ◽  
Model Predictions ◽  
Developmental Features

Individual-based models (IBMs) integrate behavioural, physiological, and developmental features and differences among individuals. Building on previous process-based models, we developed an IBM of larval Atlantic cod (Gadus morhua) that included foraging, size-, temperature-, and food-limited growth, and environmental factors such as prey-field, turbulence, and light. Direct comparison between larval fish IBMs and experimental studies is lacking. Using data from a macrocosm study on growth and feeding of larval cod, we forced the model with observed temperature and prey-field and compared model predictions with observed distribution, diet, size-at-age, and specific growth rates. We explored implications of habitat selection rules on predicted growth rates. We analyze the sensitivity of model predictions by the Latin Hypercube Sampling method and individual parameter perturbation. Food limitation prevented larvae from growing at their physiological maximum, especially in the period 5–17 days post hatch (DPH). Active habitat selection had the potential to enhance larval growth rates. The model predicted temperature-limited growth rates for first-feeding larvae (5–20 DPH) when prey density is >5 nauplii·L–1. After age 20 DPH, maximum modelled growth required a diet of copepodites. Simulated growth rates were close to observed values except for the period just after the start of exogenous feeding when prey density was low.

Growth Rates and Protein Turnover in Atlantic Cod,Gadus morhua

1988 ◽  
Vol 45 (6) ◽  
pp. 951-964 ◽  
Author(s):  
D. F. Houlihan ◽  
S. J. Hall ◽  
C. Gray ◽  
B. S. Noble
Keyword(s):  
Growth Rate ◽  
Weight Loss ◽  
Protein Synthesis ◽  
Growth Rates ◽  
Gadus Morhua ◽  
White Muscle ◽  
Atlantic Cod ◽  
Degradation Rates ◽  
Protein Synthesis And Degradation ◽  
Synthesis And Degradation

Atlantic cod, Gadus morhua, were maintained on different ration levels or starved to produce a variety of growth rates. The in vivo rates of protein synthesis and degradation were determined for the whole fish and various tissues. As ration level, and hence growth rates, increased, both whole-animal protein synthesis and degradation rates increased linearly; growth occurred because of the preponderance of synthesis over degradation. On average, a 300-g cod growing at 1.0%∙d−1synthesised 1.25 g of protein with 0.4 g of this protein remaining as growth. The proportion of total protein synthesis which was retained as growth increased with increasing growth rate; at a maximum growth rate of 2%∙d−1, over 40% of the protein synthesised was retained as growth. The ranking of the tissues in terms of fractional rates of protein synthesis was liver > gills > intestine > spleen > ventricle > stomach > gonads > white muscle. The white muscle, gills, liver, stomach, spleen, and ventricle all showed similar patterns of increased protein synthesis with increased growth rate. The white muscle has the highest efficiency of retention of protein and accounts for 40% of the total protein accretion per day. In starving fish there was a constant level of protein synthesis, irrespective of the rate of weight loss. However, degradation rates increased in the whole animal and in white muscle as the rate of weight loss increased.

scholarly journals Turbulence enhances feeding of larval cod at low prey densities

2014 ◽  
Vol 71 (9) ◽  
pp. 2515-2529 ◽  
Author(s):  
T. Kristiansen ◽  
K. W. Vollset ◽  
S. Sundby ◽  
F. Vikebø
Keyword(s):  
Vertical Distribution ◽  
Growth Rates ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Larval Fish ◽  
Larval Survival ◽  
Growth And Survival ◽  
First Feeding ◽  
High Ingestion ◽  
Biological Environment

Abstract The ability of larval fish to find food successfully after hatching is critical for their growth and survival during the early life stages. However, the feeding ecology of larval fish is strongly dependent on prevailing physical and biological conditions. Small changes in the prey distribution, turbulence, light, and ocean temperature can affect larval survival probabilities. This study combined physical and biological observations collected from Atlantic cod (Gadus morhua) spawning grounds from Lofoten, Norway, during the years 1991–1992 with an individual-based model (IBM) that is able to simulate behaviour, feeding, and growth. Observational data on the vertical distribution of larval cod revealed that they congregated at 10–25 m during the day, although the highest abundance of prey was generally in the upper 10 m. Using the behavioural component of the IBM, we analysed the mechanistic interactions between larval bioenergetics and the physical–biological environment and compared modelled with observed vertical larval cod distribution. During periods of both low and high prey densities, turbulence had a significant impact on larval cod feeding and growth rates as well as on larval vertical distribution. At low prey abundance (<5 nauplii l−1), turbulence enhanced encounter rates were very important for sustaining ingestion and growth rates for first-feeding larval cod. Our results suggest that turbulence allowed larval cod to sustain high ingestion rates even deeper in the water column, where prey densities are usually lower.

Recent Growth, Biochemical Composition and Prey Field of Larval Haddock (Melanogrammus aeglefinus) and Atlantic Cod (Gadus morhua) on Georges Bank

1987 ◽  
Vol 44 (1) ◽  
pp. 14-25 ◽  
Author(s):  
L. J. Buckley ◽  
R. G. Lough
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Dry Weight ◽  
Melanogrammus Aeglefinus ◽  
Good Growth ◽  
Georges Bank ◽  
Larval Population ◽  
Prey Biomass ◽  
Recent Growth ◽  
Haddock Melanogrammus Aeglefinus

A transect across southern Georges Bank in May 1983 showed higher levels of available prey for haddock (Melanogrammus aeglefinus) and cod (Gadus morhua) larvae at two stratified sites than at a well-mixed site. At the stratified sites, prey biomass was high (30–300 μg dry wt∙L−1) near the surface above the thermocline; values were lower and more uniform with depth (10–30 μg dry wt∙L−1) at the well-mixed site. Larval population centers generally coincided with prey biomass vertically. Recent growth in dry weight of haddock larvae as estimated by RNA–DNA ratio analysis was higher at the stratified sites (8–13%∙d−1) than at the well-mixed site (7%∙d−1). Larvae appeared to be in excellent condition at the stratified sites, but up to 50% of haddock larvae from the well-mixed site had RNA–DNA ratios in the range observed for starved larvae in the laboratory. Cod collected at the same site were in better condition and growing faster than haddock. The data support the hypotheses that (1) stratified conditions in the spring favor good growth and survival of haddock larvae and (2) cod larvae are better adapted to grow and survive in well-mixed waters at lower levels of available food than haddock larvae.

COMPARATIVE STUDIES OF NORTH AMERICAN AND EUROPEAN CULTURES OF THE ROOT ROT FUNGUS, FOMES ANNOSUS (FR.) COOKE

1955 ◽  
Vol 33 (5) ◽  
pp. 416-428 ◽  
Author(s):  
D. E. Etheridge
Keyword(s):  
Growth Rate ◽  
North American ◽  
Growth Rates ◽  
Root Rot ◽  
Linear Growth ◽  
Morphological Characteristics ◽  
Dry Weight ◽  
Cellulolytic Activity ◽  
Ph Optimum ◽  
Two Cultures

Cultures of Fames annosus originating in Europe could not be distinguished from those originating in North America either by colony appearance, growth rate, pH optimum, or cellulolytic activity. Three growth rate types on 2.5% malt agar were recognized and these are ascribed to individual variation rather than to host or geographical influences. Successive subculturing produced variants that fell into three growth classes. Half of the isolates displayed spontaneous, but reversible, changes in growth rate and colony appearance during subculturing and this is discussed from the standpoint of genetical and environmental influences. Cultures displaying different morphological characteristics and linear-growth rates differed little metabolically; each had a similar pH optimum ranging from 4.6 to 5.5, and each proved capable of altering the initial acidity of the medium to a reaction which was more suitable for growth. Two cultures were characterized by double pH optima at 4.6 and 5.5. Cultures having different linear-growth rates produced about the same dry-weight of mycelium on a cellulose substrate in a semisynthetic nutrient solution. On the basis of a statistical analysis of cellulose utilization by representative isolates it was impossible to distinguish between North American and European cultures.

Sign in / Sign up

Export Citation Format

Share Document