Position Choice by Drift-Feeding Salmonids: Model and Test for Arctic Grayling (Thymallus arcticus) in Subarctic Mountain Streams, Interior Alaska

1990 ◽  
Vol 47 (10) ◽  
pp. 2039-2048 ◽  
Author(s):  
Nicholas F. Hughes ◽  
Lawrence M. Dill
Keyword(s):  
Energy Intake ◽  
Water Depth ◽  
Focal Point ◽  
Water Velocity ◽  
Net Energy ◽  
Intake Rate ◽  
Arctic Grayling ◽  
Thymallus Arcticus ◽  
Net Energy Intake ◽  
Energy Intake Rate

We develop a model to predict position choice of drift-feeding stream salmonids, assuming a fish chooses the position that maximizes its net energy intake rate. The fish's habitat is represented as a series of stream cross-profiles, each divided into vertical strips characterized by water depth and velocity. The fish may select a focal point in any of these strips, and include several neighbouring strips in its foraging area. The number of prey the fish encounters depends on its reaction distance to prey, water depth, and water velocity; the proportion of detected prey the fish is able to capture declines with water velocity. The fish's net energy intake rate is its gross energy intake rate from feeding minus the swimming cost calculated by using water velocity at the fish's focal point. There was a close match between the positions predicted by this model and those chosen by solitary Arctic grayling (Thymallus arcticus) in the pools of a mountain stream in Alaska.

scholarly journals Net Energy Intake Rate as a Common Currency to Explain Swan Spatial Distribution in a Shallow Lake

Wetlands ◽  
2012 ◽  
Vol 32 (1) ◽  
pp. 119-127 ◽  
Author(s):  
Abel Gyimesi ◽  
Sam Varghese ◽  
Jan De Leeuw ◽  
Bart A. Nolet
Keyword(s):  
Spatial Distribution ◽  
Energy Intake ◽  
Shallow Lake ◽  
Net Energy ◽  
Intake Rate ◽  
Common Currency ◽  
Net Energy Intake ◽  
Energy Intake Rate

Optimal flight speed of birds

1995 ◽  
Vol 348 (1326) ◽  
pp. 471-487 ◽  
Keyword(s):  
Energy Intake ◽  
Flight Speed ◽  
Net Energy ◽  
Intake Rate ◽  
Variable Degree ◽  
Flock Size ◽  
Optimization Criteria ◽  
Gain Ratio ◽  
Net Energy Intake ◽  
Energy Intake Rate

The speed of birds in flapping flight is a behavioural attribute that, when interpreted in the light of optimization theory, may provide important implications about the limitations in time, energy and safety that affect birds in different situations. This study is an evaluation and review of optimal flight speeds of birds, based on foraging, migration and flight mechanical theory. Flight in different ecological contexts is considered, such as foraging flight, food transportation flight, migration flight and aerial display flight. Relevant optimization criteria and immediate currencies are identified for these flight situations, permitting the derivation of optimal flight speeds. Foraging birds are expected to maximize foraging gain ratio (the ratio of gross energy intake rate to the cost of foraging in excess of the resting metabolism) when energy minimization is of imminent importance or when they are constrained by a metabolic ceiling. In other circumstances they are expected to maximize the net energy intake rate. Generally, optimal flight speeds are faster in the latter than in the former case. Thus when the foraging gain ratio is maximized the optimal flight speed between foraging patches is V mr (speed of minimum energy cost per unit of distance flown), whereas it is faster than this, to a variable degree depending on the quality of and distance between patches, when net energy intake rate is maximized. Birds should adapt their flight speed differently when transporting food or migrating as compared with flying in pure foraging situations. Cost of transport (energy/distance) or resulting speed of transport or of migration (distance/time) are the immediate currencies relevant for predicting optimal flight speeds depending on whether birds in food transportation flights are metabolically constrained or not and whether migrating birds are energy- or time-selected. Optimal flight speeds for maximizing the resulting speed of transport or of migration exceed V mr to an increasing degree with an increasing rate of food/energy gain. Still other optimization criteria apply to further flight situations that are reviewed, and, in addition, flight speed is expected to vary with wind, load, altitude, climb rate and flock size. Optimal flight speed theory provides a possibility to use flight speed measurements of birds in widely different situations for obtaining insights about crucial time and energy limitations.

scholarly journals Human disturbance of B ewick's S wans is reflected in giving‐up net energy intake rate, but not in giving‐up food density

Ibis ◽  
2012 ◽  
Vol 154 (4) ◽  
pp. 781-790 ◽  
Author(s):  
Abel Gyimesi ◽  
Marycha S. Franken ◽  
Nicole Feige ◽  
Bart A. Nolet
Keyword(s):  
Energy Intake ◽  
Human Disturbance ◽  
Food Density ◽  
Net Energy ◽  
Intake Rate ◽  
Net Energy Intake ◽  
Energy Intake Rate

Examining feeding strategies and position choice of drift-feeding salmonids using an individual-based, mechanistic foraging model

2001 ◽  
Vol 58 (3) ◽  
pp. 446-457 ◽  
Author(s):  
G R Guensch ◽  
T B Hardy ◽  
R C Addley
Keyword(s):  
Habitat Selection ◽  
Energy Intake ◽  
Brown Trout ◽  
Salmo Trutta ◽  
Prey Capture ◽  
Feeding Strategies ◽  
Net Energy ◽  
Intake Rate ◽  
Drift Feeding ◽  
Energy Intake Rate

We demonstrated the ability of a mechanistic habitat selection model to predict habitat selection of brown trout (Salmo trutta) and mountain whitefish (Prosopium williamsoni) during summer and winter conditions in the Blacksmith Fork River, Utah. By subtracting energy costs and losses from the gross energy intake rate (GEI) obtained through simulation of prey capture, the model calculates the potential net energy intake rate (NEI) of a given stream position, which is essentially the rate of energy intake available for growth and reproduction. The prey capture model incorporates the size, swimming speed, and reaction distance of the fish; the velocity, depth, temperature, and turbidity of the water; and the density and size composition of the drifting invertebrates. The results suggest that during both summer and winter, the brown trout and mountain whitefish in our study reach avoided locations providing low NEI and preferred locations providing a high ratio of NEI to the swimming cost (SC) at the focal position of the fish (NEI/SC). This supports the idea that the drift-feeding fish in this study selected stream positions that provided adequate NEI for the least amount of swimming effort.

Mechanics of foraging success and optimal microhabitat selection in Alaskan Arctic grayling (Thymallus arcticus)

2019 ◽  
Vol 76 (5) ◽  
pp. 815-830 ◽  
Author(s):  
Bryan B. Bozeman ◽  
Gary D. Grossman
Keyword(s):  
Prey Capture ◽  
Water Velocity ◽  
Net Energy ◽  
Arctic Grayling ◽  
Drift Feeding ◽  
Reactive Distance ◽  
Negative Effect ◽  
Thymallus Arcticus ◽  
Alaskan Arctic ◽  
Size Rank

Most fishes residing in temperate streams in the Northern Hemisphere are drift-feeders. Despite this fact, little is known about the mechanisms of drift-feeding itself. We used Alaskan Arctic grayling (Thymallus arcticus), an abundant boreal drift-feeder, to examine the effects of water velocity on several aspects of drift-feeding behavior and test predictions of the Grossman et al. (2002) net energy intake model for microhabitat choice. Water velocity had a negative effect on prey capture, a positive effect on holding velocity, and little effect on reactive distance. We also found that dominance was a better predictor of prey capture success than size rank, although neither of these variables influenced holding velocity or reactive distance. The Grossman et al. (2002) model successfully predicted holding velocities of grayling in one Alaskan stream, but not another. Model failure might have occurred due to higher turbulence, increased predation, or interspecific competition with Dolly Varden (Salvelinus malma). These results help inform the study of habitat selection in drift-feeding fishes as well as management and conservation of Arctic grayling.

EFFECTS OF CORRECTING FOR FEEDING LEVELS ON ESTIMATES OF GENETIC PARAMETERS OF MILK YIELD AND COMPOSITION

1976 ◽  
Vol 56 (3) ◽  
pp. 523-529 ◽  
Author(s):  
A. K. W. TONG ◽  
B. W. KENNEDY ◽  
J. E. MOXLEY
Keyword(s):  
Energy Intake ◽  
Milk Fat ◽  
Genetic Parameters ◽  
Genetic Relationships ◽  
Protein Yield ◽  
Net Energy ◽  
Yield Traits ◽  
Genetic And Phenotypic Correlations ◽  
Net Energy Intake ◽  
Quadratic Effects

A total of 13,561 Holstein 305-day lactation records were studied to examine the effects of correcting records for linear and quadratic effects of 305-day net energy intake from silage, hay, pasture and meal feeding on estimates of genetic parameters of milk, fat and protein yield and fat and protein percent. Correcting records for net energy intake reduced variances of yield traits, but had little effect on composition trait variances. When expressed as a percentage of the total variance, the relative importance of sire and sire–herd components were unchanged using corrected records, and heritabilities, except for that of protein yield, were unaltered. Cow components of yield traits were reduced relative to other components after records were corrected for feeding levels. Consequently, repeatabilities were reduced as well, suggesting that a large portion of the permanent environmental effects on yield traits may be of nutritional origin. Genetic and phenotypic correlations between yield traits were also reduced appreciably after records were corrected for feed intake. Genetic relationships between milk, fat and protein yield may not be as great as commonly believed.

Resource selection functions for age-0 Arctic grayling (Thymallus arcticus) and their application to stream habitat compensation

2004 ◽  
Vol 61 (9) ◽  
pp. 1736-1746 ◽  
Author(s):  
Nicholas E Jones ◽  
William M Tonn
Keyword(s):  
Habitat Use ◽  
Water Depth ◽  
Resource Selection ◽  
Productive Capacity ◽  
Resource Selection Functions ◽  
Arctic Grayling ◽  
Artificial Stream ◽  
Average Water ◽  
Thymallus Arcticus ◽  
Habitat Compensation

We developed resource selection functions (RSFs) for young-of-the-year (YOY) Arctic grayling (Thymallus arcticus) in a natural Barrenlands stream and used them to assess the habitat in an artificial stream created as part of a habitat compensation agreement in the Canadian Arctic. The model for small (15–21 mm) grayling explained 55% of the variation in habitat use and included water velocity, average water depth, and percentage of detritus and fines. The model for large (38–57 mm) grayling explained 36% of the variation in habitat use and included water depth, percentage of detritus and fines, and several cover variables. Model validation using a withheld sample of data indicated that the models provided good fits to the data, correctly classifying 71–75% of habitat-use locations. Applying the RSFs to observed habitat use in the artificial stream indicated an abundance of quality habitat for small grayling, but a paucity for the larger YOY. These results reflect an ontogenetic shift in habitat requirements, from the simple needs of small YOY to the more complex demands of larger YOY, demands that could not be well met by the artificial stream. We suggest that this inability contributed to the poor productive capacity of the artificial stream.

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