Individual variation in competitive performance of juvenile cod and its consequences for growth

2000 ◽  
Vol 80 (3) ◽  
pp. 569-570 ◽  
Author(s):  
Paul J.B. Hart ◽  
Anne Gro V. Salvanes
Keyword(s):  
Gadus Morhua ◽  
Positive Influence ◽  
Individual Variability ◽  
Individual Growth ◽  
Individual Response ◽  
Competitive Performance ◽  
Marked Individual ◽  
Winter Conditions ◽  
Individual Growth Rate ◽  
The Relationship

This communication reports on experiments, which studied the variation in competitive performance of juvenile cod (Gadus morhua L.) and their growth rates. The fish were held in groups of five in either summer or winter conditions and tested for their individual response to prey offered sequentially. There was marked individual variability. Fish that took the highest share of prey tended also to be those that took prey earlier than others. In winter conditions these fish were the largest, but in summer conditions size had no effect. There was a positive influence of the indices of competitive performance on individual growth rate but the relationship was not significant

scholarly journals The effect of growth rate on otolith-based discrimination of cod (Gadus morhua) ecotypes

PLoS ONE ◽  
2021 ◽  
Vol 16 (9) ◽  
pp. e0247630
Author(s):  
Einar Pétur Jónsson ◽  
Steven E. Campana ◽  
Jón Sólmundsson ◽  
Klara B. Jakobsdóttir ◽  
Hlynur Bárðarson
Keyword(s):  
Growth Rate ◽  
Gadus Morhua ◽  
Sampling Period ◽  
Individual Growth ◽  
Discrete Wavelet ◽  
Shape Variation ◽  
Otolith Shape ◽  
Individual Growth Rate ◽  
The Individual ◽  
The Relationship

Otolith shape has previously been used to identify ecotypes within the Icelandic cod (Gadus morhua) stock, using DST profiles to validate the results. Fish otolith shape variation has repeatedly been found to be largely determined by growth rate. To examine the effect of growth rate on the relationship between otolith shape and cod ecotypes (using the Pan I genotype as a proxy for ecotype), 826 archived sagittal otoliths collected over a 58 year sampling period were retrieved, the individual growth rate calculated, and otolith shape described using both Normalized Elliptic Fourier transform and Discrete Wavelet transform. Discriminant functions of otolith shape successfully classified ecotype, whether using Fourier or Wavelet descriptors, but only when excluding a heterozygous genotype from the analysis. The otolith shape variability of this genotype lowered the classification success, while otolith shape, in turn, was significantly affected by growth rate and cohort. Growth rate differences previously reported for the ecotypes were present, but were less marked than expected and indeed, growth rate variance attributable to ecotype identity was dwarfed by cohort- and location-related variance in growth. Such a strong effect of growth rate suggests that cod ecotype discrimination based on otolith shape is sensitive to both temporal and spatial variations in growth, which can mask the effect of ecotype-related growth rate differences on otolith shape.

scholarly journals Otolith-based discrimination of cod ecotypes and the effect of growth rate

2021 ◽  
Author(s):  
Einar Pétur Jónsson ◽  
Steven E. Campana ◽  
Jón Sólmundsson ◽  
Klara B. Jakobsdóttir ◽  
Hlynur Bárðarson
Keyword(s):  
Growth Rate ◽  
Gadus Morhua ◽  
Sampling Period ◽  
Individual Growth ◽  
Discrete Wavelet ◽  
Shape Variation ◽  
Otolith Shape ◽  
Individual Growth Rate ◽  
The Individual ◽  
The Relationship

AbstractOtolith shape has previously been used to identify ecotypes within the Icelandic cod (Gadus morhua) stock, using DST profiles to validate the results. Fish otolith shape variation has repeatedly been found to be largely determined by growth rate. To examine the effect of growth rate on the relationship between otolith shape and cod ecotypes (using the Pan I genotype as a proxy for ecotype), 826 archived sagittal otoliths collected over a 52 year sampling period were retrieved, the individual growth rate calculated, and otolith shape described using both Normalized Elliptic Fourier transform and Discrete Wavelet transform. Discriminant functions of otolith shape yielded high ecotype classification success, whether using Fourier or Wavelet descriptors, but only when excluding a heterozygous genotype from the analysis. The otolith shape variability of this genotype lowered the classification success, while otolith shape, in turn, was significantly affected by growth rate and cohort. Growth rate differences previously reported for the ecotypes were present, but were less marked than expected and indeed, growth rate variance attributable to ecotype identity was dwarfed by cohort- and location-related variance in growth. Such a strong effect of growth rate suggests that cod ecotype discrimination based on otolith shape is sensitive to both temporal and spatial variations in growth, which can mask the effect of ecotype-related growth rate differences on otolith shape.

scholarly journals Age validation of juvenile cod in the Western Baltic Sea

2018 ◽  
Vol 76 (2) ◽  
pp. 430-441 ◽  
Author(s):  
Kate McQueen ◽  
Josef Hrabowski ◽  
Uwe Krumme
Keyword(s):  
Gadus Morhua ◽  
Age Determination ◽  
Individual Growth ◽  
Age Validation ◽  
Length Frequency ◽  
Individual Growth Rate ◽  
Peak Summer ◽  
Age Reading ◽  
Baltic Cod

Abstract The methods routinely used to estimate fish age are often un-validated and susceptible to errors and uncertainties. Despite numerous attempts, age determination of western Baltic cod (WBC, Gadus morhua) using otoliths is still unreliable, predominantly due to inconsistent interpretation of the first translucent zone (TZ). Length-frequencies of undersized (<38 cm) cod collected during 2013–2016 from pound nets near Fehmarn Island were analysed to understand TZ formation patterns. A clear minimum separated two cohorts within the length-frequency samples every year. The length-frequency information was combined with otolith edge analysis to observe the development of TZs in age-0 and age-1 cod otoliths, and to validate the timing of TZ formation, which was consistently completed between September and December. Mean TZ diameters of 4 917 juvenile cod otoliths varied between cohorts (mean diameters of the first TZ: 2.0 ± 0.5 mm; second TZ: 3.9 mm ± 0.5) and TZ diameter variation was found to be related to individual growth rate. The timing of formation of the first TZ was positively related to water temperature, and was confirmed as a “summer ring” rather than a “winter ring”. TZ formation and shallow-water occupancy suggest an influence of peak summer water temperatures on WBC ecology. An age reading guide for juvenile WBC otoliths is provided.

Influence of growth and survival costs of reproduction on Atlantic cod, Gadus morhua, population growth rate

1999 ◽  
Vol 56 (9) ◽  
pp. 1612-1623 ◽  
Author(s):  
Jeffrey A Hutchings
Keyword(s):  
Growth Rate ◽  
Population Growth ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Environmental Stochasticity ◽  
Individual Growth ◽  
Growth And Survival ◽  
Individual Growth Rate ◽  
Age Structured ◽  
Reproductive Rates

A stochastic, age-structured life history model was used to examine how age at maturity (theta), pre- (Zimm) and postreproductive (Zmat) mortality, and postreproductive growth rate can affect maximum reproductive rates of fish at low population size. Simulations suggest that annual (r) and per-generation (R0) metrics of population growth for Newfoundland's northern Grand Bank Atlantic cod, Gadus morhua, are primarily influenced by changes to mortality prior to and following reproduction. At observed weights at age and Zmat = 0.2, r ranged between 0.135 and 0.164 for cod maturing at between 4 and 7 years. Incremental increases in either Zimm or Zmat of 0.1 were associated with 0.03-0.05 reductions in r. To effect similar reductions, individual growth rate would have to decline by approximately one half. At observed weights at age, increases in Zmat from 0.20 to 0.45 increased the probability of negative per-generation growth from 3 to 26% for cod maturing at 4 years and from 6 to 46% for cod maturing at 7 years. Thus, even in the absence of fishing mortality, little or no population growth by Atlantic cod may not be unexpected in the presence of environmental stochasticity, particularly when accompanied by increases in mortality and declining individual growth.

scholarly journals Effects of temperature on individual growth rate and body size of a freshwater amphipod

1998 ◽  
Vol 76 (6) ◽  
pp. 1107-1116 ◽  
Author(s):  
Vadim E Panov ◽  
Donald J McQueen
Keyword(s):  
Growth Rates ◽  
Negative Relationship ◽  
Maximum Size ◽  
Growth Efficiency ◽  
Individual Growth ◽  
Summer Temperatures ◽  
Individual Growth Rate ◽  
Natural Temperature ◽  
Effects Of Temperature ◽  
The Relationship

Individual growth rates of the freshwater amphipod Hyalella azteca (Saussure) were measured in the littoral zone oftwo small oligotrophic Ontario lakes and in growth experiments over a natural temperature gradient (10, 15, 20, and 238C).Field observations showed that a temperature of 208C is important for both the induction and termination of reproductiveresting stages in H. azteca. Growth rates were more affected by temperature in small than in large individuals. Growthparameters are related to rearing temperature by linear regressions, which can be used as a simple model for bioenergeticscalculations in crustaceans. A negative relationship between water temperature and maximum size attained by the amphipodswas found. The largest adults were absent in studied populations when summer temperatures were high, and this phenomenon,which has also been observed in other aquatic invertebrates, was bioenergetically determined. Energy-budget estimationsshowed negative net growth efficiency (K2) in the largest adults at temperatures above 208C. The relationship between K2andtemperature showed a dome-shaped pattern, K2values for larger amphipods being maximal at lower temperatures. Seasonalmigrations of adult H. azteca from shallow littoral to deeper cold habitats, observed in lakes during the warmest periods, appearto be temperature-induced and bioenergetically advantageous, despite probable increases in predation risk experienced inspatially simple deep-water habitats.

Dental Fluorosis: Its Use as a Biomarker

1994 ◽  
Vol 8 (1) ◽  
pp. 105-110 ◽  
Author(s):  
P.K. Den Besten
Keyword(s):  
Dental Fluorosis ◽  
Biological Marker ◽  
Epidemiological Studies ◽  
Individual Variability ◽  
Activity Level ◽  
Individual Response ◽  
Growth And Remodeling ◽  
Nutritional Factors ◽  
Fluoride Exposure ◽  
The Relationship

Several epidemiological studies, beginning with those of Dean and co-workers in the 1940's, clearly demonstrate the relationship between dental fluorosis in humans and the level of fluoride in water supplies. These studies and others have shown that, in a population, there is a direct relationship among the degree of enamel fluorosis, plasma and bone fluoride levels, and the concentration of fluoride in drinking water. However, dental fluorosis is a reflection of fluoride exposure only during the time of enamel formation, somewhat limiting its use as a biomarker. In addition, the degree of fluorosis is dependent not only on the total fluoride dose, but also on the timing and duration of fluoride exposure. At the level of an individual response to fluoride exposure, factors such as body weight, activity level, nutritional factors, and the rate of skeletal growth and remodeling are also important. These variables, along with an individual variability in response to similar doses of fluoride, indicate that enamel fluorosis cannot be used as a biological marker of the level of fluoride exposure for an individual.

INDIVIDUAL VARIATION OF GROWTH AND FILTRATION RATES OF MUSSELS MYTILUS GALLOPROVINCIALIS LAM

2017 ◽  
Author(s):  
Irina Kazankova ◽  
Irina Kazankova ◽  
Elena Vasechkina ◽  
Elena Vasechkina
Keyword(s):  
Growth Rate ◽  
Individual Variation ◽  
Coefficient Of Variation ◽  
Individual Variability ◽  
Individual Growth ◽  
Rate Variation ◽  
Sample Mean ◽  
Metabolic Costs ◽  
Individual Growth Rate ◽  
The Mean

Research on individual variation of the filtration and growth rates of mussels was based both on the authors’ field and laboratory experiments and literature data analysis. High individual variability of these characteristics was recorded during the tests. The coefficient of variation grew up as the mean rate diminished. Under low specific growth rate the coefficient of variation (ratio of root-mean-square deviation to the sample mean) could exceed 100 %. Tests revealed the power-law relation of the coefficient of variation from the average for studied characteristics. That relation could be seen in filtration and growth rate charts; it was also true for estimates of production energy and metabolic costs. The exponent varied from -0.36 to -0.77. Individual growth rate variation of mussels was concluded to be an important criterion of the favorability of environmental conditions.

INDIVIDUAL VARIATION OF GROWTH AND FILTRATION RATES OF MUSSELS MYTILUS GALLOPROVINCIALIS LAM

2017 ◽  
Author(s):  
Irina Kazankova ◽  
Irina Kazankova ◽  
Elena Vasechkina ◽  
Elena Vasechkina
Keyword(s):  
Growth Rate ◽  
Individual Variation ◽  
Coefficient Of Variation ◽  
Individual Variability ◽  
Individual Growth ◽  
Rate Variation ◽  
Sample Mean ◽  
Metabolic Costs ◽  
Individual Growth Rate ◽  
The Mean

Research on individual variation of the filtration and growth rates of mussels was based both on the authors’ field and laboratory experiments and literature data analysis. High individual variability of these characteristics was recorded during the tests. The coefficient of variation grew up as the mean rate diminished. Under low specific growth rate the coefficient of variation (ratio of root-mean-square deviation to the sample mean) could exceed 100 %. Tests revealed the power-law relation of the coefficient of variation from the average for studied characteristics. That relation could be seen in filtration and growth rate charts; it was also true for estimates of production energy and metabolic costs. The exponent varied from -0.36 to -0.77. Individual growth rate variation of mussels was concluded to be an important criterion of the favorability of environmental conditions.

Analisis Peranan Kepuasan Dan Komitmen Sebagai Perantara Pengaruh Kualitas Jasa Tutorial Online Terhadap Loyalitas Mahasiswa

2018 ◽  
Vol 9 (2) ◽  
pp. 18-32
Author(s):  
Andy Mulyana ◽  
Devi Ayuni
Keyword(s):  
Service Quality ◽  
Structural Equation ◽  
Positive Influence ◽  
Management Program ◽  
Equation Modeling ◽  
Online Tutorial ◽  
Student Loyalty ◽  
The Relationship ◽  
Positive Effect

This study aims to evaluate the role of satisfaction and commitment as mediating the effect of service quality on student loyalty as the user of Open University's Online Tutorial. Based on data analysis on student of Management program 229 as respondents with Structural Equation Modeling (SEM), this study found the relationship between: (1) positive influence of service quality to satisfaction and loyalty of students using tuton; (2) the positive effect of satisfaction on student loyalty using tuton; (3) satisfaction is a mediator between service quality and loyalty of students using tuton. Conversely, commitment has no positive effect on student loyalty as a tuton user. In addition, commitment does not mediates the effect of satisfaction on the loyalty of tuton users. Keywords: service quality, satisfaction, commitment, loyalty

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