Prediction of Fish Growth Efficiency in Nature

1971 ◽  
Vol 28 (6) ◽  
pp. 809-814 ◽  
Author(s):  
S. R. Kerr
Keyword(s):  
Metabolic Cost ◽  
Growth Efficiency ◽  
Equation System ◽  
Fish Growth ◽  
Empirical Literature ◽  
Large Prey ◽  
Sustained Growth ◽  
Physiological Properties

Using an equation system based upon the requirements of searching for prey, and the physiological properties of the predator, the hypothesis that growth efficiency of pelagic predators may be importantly determined by the metabolic cost of searching for prey is examined. The equation system indicates that growth efficiency decreases when the prey organisms become either rare or small in relation to the size of the predator. The system also indicates that sustained growth requires increasingly large prey organisms even if these are increasingly rare. Review of empirical literature indicates that the system's predictions are in accord with observation.

scholarly journals Nutritional innovations on amino acids supplementation in Nile tilapia diets

2010 ◽  
Vol 39 (suppl spe) ◽  
pp. 88-94 ◽  
Author(s):  
Wilson Massamitu Furuya ◽  
Valéria Rossetto Barriviera Furuya
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Environmental Sustainability ◽  
Growth Efficiency ◽  
Fish Growth ◽  
Amino Acid Requirement ◽  
Amino Acid Requirements ◽  
Ideal Protein ◽  
Fillet Yield ◽  
Internal And External Factors

The optimal dietary supply of amino acids to tilapia has been studied for many years. Nevertheless, a general agreement on the amino acid requirement for tilapias has not been established. In order to optimize efficiency and reduce surplus nitrogen, values of digestibility of each amino acid of feed must be considered. Due to variations in the amino acid requirement due to new tilapia strains introduction, continuous research on amino acid requirements is necessary to elaborate economical and environmental sustainability diets, also improving fish growth, efficiency and fillet yield. The concept of ideal protein in tilapia diets was introduced more than ten years ago, and new researches have shown the importance of protein and amino acids on fish performance and health, when tilapias are submitted to constant challenging from internal and external factors.

A Simulation Model of Lake Trout Growth

1971 ◽  
Vol 28 (6) ◽  
pp. 815-819 ◽  
Author(s):  
S. R. Kerr
Keyword(s):  
Simulation Model ◽  
Growth Model ◽  
Lake Trout ◽  
Growth Efficiency ◽  
Equation System ◽  
Growth Increments ◽  
Predator Size ◽  
Mean Size ◽  
The Mean

Kerr (J. Fish. Res. Bd. Canada 28: 809–814, 1971) described an equation system based upon metabolic constraints and foraging limitations that predicts level of rations and growth efficiency as a function of the availability of the prey resource. An algorithm that extends the equation system to a growth model is described here. With reference to increasing predator size, and to the mean size and abundance of prey, the model computes successive growth increments while holding the equations to the configuration that maximizes the ratio of growth efficiency to rations. When given information on the mean size and density of prey organisms, the model accurately predicts observed patterns of lake trout growth.

scholarly journals Church attendance, faith and the allocation of time: evidence from Australia

2017 ◽  
Vol 44 (12) ◽  
pp. 2112-2127 ◽  
Author(s):  
Michael A. Kortt ◽  
Todd Steen ◽  
Elisabeth Sinnewe
Keyword(s):  
Church Attendance ◽  
Equation System ◽  
Reduced Form ◽  
Empirical Literature ◽  
Hourly Wage ◽  
Content Type ◽  
Endogenous Variables ◽  
Hourly Wage Rate ◽  
Allocation Of Time ◽  
Time Variables

Purpose The purpose of this paper is to examine the determinants of church attendance and the formation of “religious human capital” using a Becker-inspired allocation-of-time framework. Design/methodology/approach Data derived from three waves of the Household, Income and Labour Dynamics in Australia Survey were used to estimate a reduced-form two-equation system where the endogenous variables were frequency of attendance at religious services and intensity of faith. Findings The results indicate that while the hourly wage rate accounts for some of the variation in the attendance and faith regressions (i.e. higher wages lead to lower levels of attendance and faith), “allocation of time” variables like working long hours also influence these dimensions. The findings also suggest that the decision to attend or not or to have any faith at all is generally independent from economic factors. However, once the decision to attend or to have faith is made, an individual’s wage influences the degree of attendance or faith to a significant level. Originality/value The study contributes to this embryonic body of empirical literature by providing – to the best of the authors’ knowledge – the first results for Australia.

Daily Feeding Rates of Bluegill (Lepomis macrochirus) Determined by a Refined Radioisotope Method

1974 ◽  
Vol 31 (1) ◽  
pp. 67-74 ◽  
Author(s):  
Seppo E. Kolehmainen
Keyword(s):  
Lepomis Macrochirus ◽  
Elimination Rate ◽  
Daily Intake ◽  
Seasonal Fluctuation ◽  
Nonequilibrium State ◽  
Growth Efficiency ◽  
Fish Growth ◽  
Feeding Rates ◽  
Radioisotope Method ◽  
Daily Feeding

The daily values of 137Cs intake by bluegill (Lepomis macrochirus) from a small impoundment receiving low-level radioactive effluents were used to calculate the daily feeding rates of the fish. The calculations of 137Cs intake, for a nonequilibrium state, were based on fish growth, the seasonal fluctuation of 137Cs concentration in fish, and the temperature-elimination rate relationship. The feeding rates were obtained by dividing the daily intake of 137Cs by the concentration of 137Cs in the diet. The daily meal of bluegill varied from 0.8% of body weight in February to 3.2% in June with an annual mean of 1.75%. There was a positive correlation (r2 = 0.805) between the daily meal and the daily temperature. The ecological growth efficiency was 4.2% during the period from April to October.

scholarly journals Influence of food web structure on the growth and bioenergetics of lake trout (Salvelinus namaycush)

2002 ◽  
Vol 59 (10) ◽  
pp. 1593-1605 ◽  
Author(s):  
Ivano Pazzia ◽  
Marc Trudel ◽  
Mark Ridgway ◽  
Joseph B Rasmussen
Keyword(s):  
Lake Trout ◽  
Assimilation Efficiency ◽  
Growth Efficiency ◽  
Salvelinus Namaycush ◽  
Fish Growth ◽  
Energy Budgets ◽  
Caloric Content ◽  
Food Web Structure ◽  
Metabolic Costs ◽  
Consumption Rates

In this study, we compared energy budgets of lake trout (Salvelinus namaycush) populations in contrasting food webs. Nonpiscivorous lake trout (NPLT) reached a much smaller size and grew at a much slower rate than piscivorous lake trout (PLT) populations. Food consumption rates were, on average, 2–3 times higher in NPLT when they were expressed on a wet weight basis. However, only a slight (less than 10%) difference in their energy intake was detected once consumption rates were corrected for differences in prey caloric content. Growth efficiency was approximately two times lower in NPLT compared with PLT, while their metabolic costs were higher and their assimilation efficiency was lower. It is most likely that the increased metabolic costs were associated with higher foraging costs, since more feeding attempts must be made to acquire a given quantity of food when fish are feeding on smaller prey. Furthermore, the portion of indigestible matter is likely to be higher in the diet of NPLT than in PLT (i.e., chitin vs. bone). These results are consistent with theoretical models of fish growth that show that lake trout must have access to larger prey, even if they are rare, to reach larger body sizes.

Actomyosin ATPase activities in the brachiopod Terebratalia transversa

1979 ◽  
Vol 57 (10) ◽  
pp. 1944-1949 ◽  
Author(s):  
William P. Eshleman ◽  
Jerrel L. Wilkens
Keyword(s):  
Inorganic Phosphate ◽  
Slow Rate ◽  
Metabolic Cost ◽  
Isotonic Contraction ◽  
Contractile System ◽  
Physiological Properties ◽  
Cross Bridges ◽  
Kinetics Of ◽  
Low Activity ◽  
Macromolecular Organization

Actomyosin specific adenosine triphosphate (AM-ATPase) activities of muscles of the articulate brachiopod Terebratalia transversa were determined in an attempt to understand some of their unusual physiological properties. The striated adductors, smooth adductors, and ventral adjustors have activities of 0.318, 0.089, and 0.050 μmol of inorganic phosphate per minute per milligram of protein respectively, which correlate with their contraction rates and behaviors. The suggestion that sudden compliance to stretch in the diductor muscles (slip) is due to simultaneous breakage of all cross bridges is supported by the low activity of 0.022 μmol of inorganic phosphate per minute per milligram of protein. This rate of activity is not as low as expected from the extremely slow rate of isometric contraction (186 min) but it does correlate with the faster rate of isotonic contraction observed after removal of the antagonistic smooth adductors. Slippage represents a previously unknown extreme in the macromolecular organization and kinetics of a contractile system, an elegant adaptation of articulate brachiopods to minimize the metabolic cost of keeping the valves open while allowing rapid closure in an emergency.

Among-Population Variability of Fish Growth: II. Influence of Prey Type.

1989 ◽  
Vol 46 (3) ◽  
pp. 468-482 ◽  
Author(s):  
D. Boisclair ◽  
W. C. Leggett
Keyword(s):  
Growth Rates ◽  
Prey Size ◽  
Prey Type ◽  
Growth Efficiency ◽  
Population Variability ◽  
Fish Growth ◽  
Percent Contribution ◽  
The Mean ◽  
Taxonomic Groups ◽  
The Relationship

We tested the significance of the relationship between in situ growth and several diet descriptors using 12 yellow perch (Perca flavescens) populations that varied widely in growth rates. In addition, we tested the assumption of optimal foraging theory that mean prey size is an important regulator of fish growth. The percent contribution of four prey taxonomic groups and six prey size–classes (alone or combined with food consumption estimates) explained between 41 and 95% of among-population variability in growth rates or growth efficiency. We found no significant relationship between growth rates or growth efficiency and mean prey weight. We observed a pattern suggesting the existence of an optimal prey size for (1 mg dry weight) age I + and age II + fish, when the percent contribution of specific prey taxonomic groups or size–classes to the diet was assessed. This pattern was not apparent in the relationship between growth and the mean weight of prey consumed. The energetic advantage of feeding on a given prey type is believed to be related to its low cost/benefit ratio while foraging. Our data indicate that interactions between prey availability (index of searching component of foraging cost) and prey size (index of handling component of foraging cost) are more effectively represented by the percent contribution of a given prey type to the diet than by the mean weight of prey consumed. Our analyses lead us to conclude that the probability of deriving broadly applicable models explaining among-population variability in fish growth rates based on mean prey weight is very low.

scholarly journals Fish face a trade-off between ‘eating big’ for growth efficiency and ‘eating small’ to retain aerobic capacity

2017 ◽  
Vol 13 (9) ◽  
pp. 20170298 ◽  
Author(s):  
Tommy Norin ◽  
Timothy D. Clark
Keyword(s):  
Prey Size ◽  
Growth Efficiency ◽  
Specific Dynamic Action ◽  
Meal Size ◽  
Large Prey ◽  
Lates Calcarifer ◽  
Trade Off ◽  
Trade Offs ◽  
Size Growth ◽  
Growth And Reproduction

Feeding provides the necessary energy to fuel all fitness-related processes including activity, growth and reproduction. Nevertheless, prey consumption and digestive processes can have physical and physiological trade-offs with other critical functions, many of which are not clearly understood. Using an ambush predator, barramundi ( Lates calcarifer ), fed meals ranging 0.6–3.4% of body mass, we examined interrelations between meal size, growth efficiency and surplus aerobic metabolic capacity (aerobic scope, AS). Large meals required a greater absolute investment of energy to process (a larger so-called specific dynamic action, SDA), but the percentage of digestible meal energy required in the SDA response (SDA coefficient) decreased with increasing meal size. Combined with the findings that growth rate and growth efficiency also increased with food intake, our results demonstrate that it is energetically advantageous for fish to select large prey. However, following a large meal, SDA processes occupied up to 77% of the available AS, indicating that other oxygen-demanding activities like swimming may be compromised while large meals are processed. This trade-off between meal size and AS suggests that fishes like barramundi would benefit from regulating prey size based on imminent requirements and threats.

Social Capital: Promise and Pitfalls of its Role in Development

2000 ◽  
Vol 32 (2) ◽  
pp. 529-547 ◽  
Author(s):  
ALEJANDRO PORTES ◽  
PATRICIA LANDOLT
Keyword(s):  
Social Capital ◽  
Latin American ◽  
Currency Crises ◽  
National Development ◽  
Empirical Literature ◽  
Economic Policies ◽  
Sustained Growth ◽  
Community Monitoring ◽  
Adjustment Policies ◽  
And Migration

The purpose of this commentary is threefold. First, to review the origins and definitions of the concept of social capital as it has developed in the recent literature. Second, to examine the limitations of this concept when interpreted as a causal force able to transform communities and nations. Third, to present several relevant examples from the recent empirical literature on Latin American urbanisation and migration. These examples point to the significance of social networks and community monitoring in the viability of grass-roots economic initiatives and the simultaneous difficulty of institutionalising such forces.Current interest in the concept of social capital in the field of national development stems from the limitations of an exclusively economic approach toward the achievement of the basic developmental goals: sustained growth, equity, and democracy. The record of application of neoliberal adjustment policies in less developed nations is decidedly mixed, even when evaluated by strict economic criteria. Orthodox adjustment policies have led to low inflation and sustained growth in some countries, while in others they have failed spectacularly, leading to currency crises, devaluations, and political instability. The ‘one-size-fits- all’ package of economic policies foisted by the International Monetary Fund and the US Treasury on countries at very different levels of development have led to a series of contradictory outcomes that orthodox economic theory itself is incapable of explaining.

Sign in / Sign up

Export Citation Format

Share Document