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.

Testing a model of drift-feeding using three-dimensional videography of wild brown trout, Salmo trutta, in a New Zealand river

2003 ◽  
Vol 60 (12) ◽  
pp. 1462-1476 ◽  
Author(s):  
Nicholas F Hughes ◽  
John W Hayes ◽  
Karen A Shearer ◽  
Roger G Young
Keyword(s):  
Brown Trout ◽  
Salmo Trutta ◽  
Focal Point ◽  
Three Dimensional ◽  
Size Composition ◽  
Invertebrate Drift ◽  
Intake Rate ◽  
Drift Feeding ◽  
Foraging Area ◽  
Brown Trout Salmo Trutta

We tested the assumptions and predictions of a foraging model for drift-feeding fish. We used three-dimensional videography to describe the foraging behavior of brown trout, Salmo trutta, mapped water depth and velocity in their foraging area, sampled invertebrate drift to determine length class specific drift densities, and captured trout to determine the size composition of their diet. The model overestimated the fish's prey capture rate and gross energy intake rate by a factor of two. Most of this error resulted from the fact that prey detection probabilities within the fish's foraging area averaged only half the expected value. This was the result of a rapid decrease in capture probability with increasing lateral distance from the fish's focal point. Some of the model's assumptions were accurate: equations for predicting reaction distance and minimum prey size supported reliable predictions of the shape and size of the fish's foraging area and the size composition of the diet. Other assumptions were incorrect: fish detected prey within the predicted reaction volume, not on its upstream surface as expected, fish intercepted prey more slowly than the expected maximum sustainable swimming speed, and fish captured about two-thirds of their prey downstream of their focal point, rather than upstream.

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

The Role of Energy Intake Rate in Prey and Habitat Selection of Common Eiders Somateria mollissima in Winter: A Risk-Sensitive Interpretation

10.2307/5615 ◽  
1992 ◽  
Vol 61 (3) ◽  
pp. 599 ◽  
Author(s):  
Magella Guillemette ◽  
Ronald C. Ydenberg ◽  
John H. Himmelman
Keyword(s):  
Habitat Selection ◽  
Energy Intake ◽  
Intake Rate ◽  
Somateria Mollissima ◽  
Risk Sensitive ◽  
Common Eiders ◽  
Energy Intake Rate ◽  
Selection Of

Do large herbivores select a diet that maximizes short-term energy intake rate?

1996 ◽  
Vol 88 (1-2) ◽  
pp. 149-156 ◽  
Author(s):  
S.E. van Wieren
Keyword(s):  
Energy Intake ◽  
Intake Rate ◽  
Short Term ◽  
Large Herbivores ◽  
Term Energy ◽  
Energy Intake Rate
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