Adaptive Flexibility in the Foraging Behavior of Fishes

1983 ◽  
Vol 40 (4) ◽  
pp. 398-408 ◽  
Author(s):  
Lawrence M. Dill
Keyword(s):  
Feeding Behavior ◽  
Foraging Behavior ◽  
Food Availability ◽  
Graphical Model ◽  
Coho Salmon ◽  
Behavioral Flexibility ◽  
Rate Of Change ◽  
Natural Environments ◽  
Feeding Rates ◽  
Risk Of Predation

Flexibility is an important adaptive feature of the foraging behavior of fishes, because most natural environments vary both spatially and temporally. Fish should respond to low levels of food availability by altering their behavior in ways which ensure higher feeding rates, larger feeding territories, and broader diets. It is shown that the gastric sensation of hunger and its rate of change may act as appropriate cues to food availability, and observed hunger-motivated changes in feeding behavior can produce all of these predicted effects. Data are presented to show that juvenile coho salmon (Oncorhynchus kisutch) alter their behavior in an adaptive manner when faced with variable degrees of threat of competition from territorial intruders, and of risk of predation. A review of similar studies on other species supports the generality of these results. Learning is an important mechanism providing behavioral flexibility, and changes in fish feeding behavior with experience are summarized. A graphical model is developed to show that these changes can result in training biases and food specialization. Learning also results in increased feeding rates. The consequences of these observations for the development of refined models of foraging are discussed.

Physiological Response of Juvenile Coho Salmon (Oncorhynchus kisutch) and Rainbow Trout (Salmo gairdneri) to Handling and Crowding Stress in Intensive Fish Culture

1976 ◽  
Vol 33 (12) ◽  
pp. 2699-2702 ◽  
Author(s):  
Gary A. Wedemeyer
Keyword(s):  
Rainbow Trout ◽  
Feeding Behavior ◽  
Coho Salmon ◽  
Physiological Stress ◽  
Oncorhynchus Kisutch ◽  
Fish Distribution ◽  
Salmo Gairdneri ◽  
Crowding Stress ◽  
Normal Feeding ◽  
Intensive Fish Culture

Moving 4–5-in. coho salmon (Oncorhynchus kisutch) held in soft (20 ppm CaCO3) water from the relatively light loading density of 0.5 lb/ft3 to 1, 2, or 4 lb/ft3 (density index, DI = 0.1, 0.2, 0.4, 0.8) caused significant stress as indicated by loss of feeding behavior, but only minimal physiological disturbances, as indicated by lack of hyperglycemia or hypochloremia. However, moving them to 6 or 12 lb/ft3 (DI = 1.2, 2.4) caused significant physiological stress which required at least a week for recovery. Smolting coho salmon were physiologically stressed by population densities of 1 lb/ft3 or more and a subclinical corynebacterial kidney infection was activated. Rainbow trout (Salmo gairdneri) (4–5 in.) were physiologically stressed when moved and held at 1 lb/ft3 or more but retained normal feeding behavior. This indicates that handling and crowding stress will be minimized in softwater areas if densities in fish distribution trucks or in ponds or raceways during disease treatments are held to 0.1–0.5 lb/gal.

Comparative Agonistic and Feeding Behavior of Hatchery-Reared and Wild Salmon in Aquaria

1968 ◽  
Vol 25 (1) ◽  
pp. 1-14 ◽  
Author(s):  
Owen C. Fenderson ◽  
W. Harry Everhart ◽  
Kenneth M. Muth
Keyword(s):  
Social Interaction ◽  
Atlantic Salmon ◽  
Feeding Behavior ◽  
Salmo Salar ◽  
Social Dominance ◽  
Food Preference ◽  
Feeding Rate ◽  
Feeding Time ◽  
Feeding Rates ◽  
Wild Salmon

When hatchery-reared and wild landlocked Atlantic salmon (Salmo salar) parr of the same age and size were permitted to compete for social dominance and for food in aquaria, twice as many hatchery salmon attained dominance as wild salmon. Dominant hatchery salmon also showed a higher intensity of aggressiveness than dominant wild salmon, displaying a higher and more variable mean nipping rate. Socially dominant salmon ate more food per fish than subordinates, but there were no statistically significant differences in feeding rate between dominant hatchery and dominant wild salmon, or between subordinate hatchery and subordinate wild salmon.Hatchery salmon displayed lower feeding rates than wild salmon when they were held in separate compartments of an aquarium and compared at three temperatures. This difference in feeding rate probably was not a reflection of differences in adaptation to temperature or food preference, but, rather, was the result of interference with feeding caused by the more intense social interaction among hatchery fish.It is suggested that high levels of aggressiveness may contribute to mortalities of hatchery-reared salmon planted in streams because of loss of feeding time, excessive use of energy, and increased exposure to predators.

Changes in Territorial, Gill-flaring, and Feeding Behavior in Juvenile Coho Salmon (Oncorhynchus kisutch) following Short-term Pulses of Suspended Sediment

1985 ◽  
Vol 42 (8) ◽  
pp. 1410-1417 ◽  
Author(s):  
L. Berg ◽  
T. G. Northcote
Keyword(s):  
Feeding Behavior ◽  
Suspended Sediment ◽  
Brine Shrimp ◽  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
Turbid Water ◽  
Short Term ◽  
Dominance Hierarchies ◽  
Short Term Exposure ◽  
Laboratory Stream

The territorial, gill-flaring, and feeding behavior of juvenile coho salmon (Oncorhynchus kisutch) in a laboratory stream was disrupted by short-term exposure to suspended sediment pulses. At the higher turbidities tested (30 and 60 nephelometric turbidity units (NTU)), dominance hierarchies broke down, territories were not defended, and gill flaring occurred more frequently. Only after return to lower turbidities (0–20 NTU) was social organization reestablished. The reaction distance of the fish to adult brine shrimp decreased significantly in turbid water (30 and 60 NTU) as did capture success per strike and the percentage of prey ingested. Implications of these behavioral modifications suggest that the fitness of salmonid populations exposed to short-term pulses of suspended sediment may be impaired.

scholarly journals A laboratory-calibrated model of coho salmon growth with utility for ecological analyses

2018 ◽  
Vol 75 (5) ◽  
pp. 682-690 ◽  
Author(s):  
Christopher V. Manhard ◽  
Nicholas A. Som ◽  
Russell W. Perry ◽  
John M. Plumb
Keyword(s):  
Food Availability ◽  
Coho Salmon ◽  
Meta Analysis ◽  
Growth Patterns ◽  
Growth Data ◽  
Experimental Conditions ◽  
Wide Range ◽  
Klamath Basin ◽  
Constructed Ponds ◽  
Dependent Growth

We conducted a meta-analysis of laboratory- and hatchery-based growth data to estimate broadly applicable parameters of mass- and temperature-dependent growth of juvenile coho salmon (Oncorhynchus kisutch). Following studies of other salmonid species, we incorporated the Ratkowsky growth model into an allometric model and fit this model to growth observations from eight studies spanning ten different populations. To account for changes in growth patterns with food availability, we reparameterized the Ratkowsky model to scale several of its parameters relative to ration. The resulting model was robust across a wide range of ration allocations and experimental conditions, accounting for 99% of the variation in final body mass. We fit this model to growth data from coho salmon inhabiting tributaries and constructed ponds in the Klamath Basin by estimating habitat-specific indices of food availability. The model produced evidence that constructed ponds provided higher food availability than natural tributaries. Because of their simplicity (only mass and temperature are required as inputs) and robustness, ration-varying Ratkowsky models have utility as an ecological tool for capturing growth in freshwater fish populations.

An evaluation of the Clearwater River supplementation program in western Washington

2006 ◽  
Vol 63 (2) ◽  
pp. 423-437 ◽  
Author(s):  
Rishi Sharma ◽  
Gary Morishima ◽  
Shizhen Wang ◽  
André Talbot ◽  
Larry Gilbertson
Keyword(s):  
Coho Salmon ◽  
Reproductive Efficiency ◽  
Natural Environments ◽  
Brood Stock ◽  
Natural Origin ◽  
High Productivity ◽  
Western Washington ◽  
Queets River ◽  
Research Questions ◽  
Clearwater River

This paper presents preliminary results of a study to evaluate the potential utility of supplementation of natural origin coho salmon (Oncorhynchus kisutch) on the Clearwater River, a tributary of the Queets River in western Washington. The study, initiated in 1984, involves the collection of natural origin brood stock, rearing in a combination of hatchery and natural environments, and volitional releases, combined with marking and sampling of natural origin fish. Primary findings relative to five essential research questions of this study concluded that (i) smolts from supplementation returned at a lower rate than natural smolts; (ii) the reproductive efficiency (spawner to spawner) of fish taken for supplementation was higher than that for fish allowed to spawn naturally; (iii) supplemental fish successfully reproduced and the combined supplemental–natural spawning population had a high productivity; (iv) supplementation did not appear to have affected the overall reproductive performance of the population for the duration of the project; and (v) supplementation increased the overall spawner return on the Clearwater River and is required to maximize adult production, unless conditions in both freshwater and ocean environments are optimal.

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