Ontogeny of feeding behaviour in hatchery-reared rainbow trout, Salmo gairdneri Richardson

1980 ◽  
Vol 58 (1) ◽  
pp. 20-26 ◽  
Author(s):  
Hugh R. MacCrimmon ◽  
Timothy K. Twongo
Keyword(s):  
Rainbow Trout ◽  
Feeding Behaviour ◽  
Feeding Activity ◽  
Artemia Salina ◽  
Artificial Feeding ◽  
Food Type ◽  
Salmo Gairdneri ◽  
Agonistic Behaviour ◽  
Exogenous Feeding ◽  
First Feeding

Development of feeding behaviour in young rainbow trout, Salmo gairdneri, from "swim-up" to day 57 after hatch at 8.5 °C is described relative to food type (live Artemia salina or dry trout ration) and water flow (current or no current). Earliest signs of feeding behaviour appear during the process of swim-up at days 27 to 29, with the movement of the eyes to fixate particles and the beginning of a snap response which intensifies within 2 days. Initially the alevins are nonselective between food and inert targets, but by about day 25 at the test temperature they have become able to discriminate food from nonfood items, and show a marked increase in exogenous feeding activity. The timing, which will differ at different rearing temperatures, coincides approximately with final absorption of the visible yolk sac and follows disappearance of the oesophageal plug by about 10 days. This would seem to be the best time to initiate artificial feeding of hatchery-reared alevins, with the fish showing a preference for ingestion of live food (shrimp nauplii) over dry rations. Despite evident behavioural differences in current and no-current conditions this factor had little effect on timing or ultimate success of first feeding. Failure of some alevins to begin feeding, or feed adequately for survival, is associated with the agonistic behaviour of more aggressive siblings.

Predation by Rainbow Trout (Salmo gairdneri): the Effect of Experience

1971 ◽  
Vol 28 (12) ◽  
pp. 1847-1852 ◽  
Author(s):  
D. M. Ware
Keyword(s):  
Rainbow Trout ◽  
Feeding Behaviour ◽  
Image Formation ◽  
Current Work ◽  
Salmo Gairdneri ◽  
Palatable Food ◽  
Food Particles

Rainbow trout (Salmo gairdneri) provided with unfamiliar palatable food changed several components of their feeding behaviour and demonstrated that they can develop searching images for specific prey. Naive fish required an average of 4 days of experience, each of which consisted of exposure to six food particles, before they approached novel prey. After this time the distance from which trout attacked food improved and had doubled by the 12th day of exposure. When conditioned animals were deprived of experience for 90 days, the distance of reaction fell back to the initial naive level. The relation of these results to current work on searching image formation is discussed.

Significance of the Timing of Initial Feeding in Hatchery Rainbow Trout, Salmo gairdneri

1976 ◽  
Vol 33 (9) ◽  
pp. 1914-1921 ◽  
Author(s):  
Timothy K. Twongo ◽  
Hugh R. MacCrimmon
Keyword(s):  
Rainbow Trout ◽  
Abdominal Cavity ◽  
Food Presentation ◽  
Ingestive Behavior ◽  
Salmo Gairdneri ◽  
Food Ingestion ◽  
Young Fish ◽  
Subsequent Growth ◽  
Exogenous Feeding ◽  
Hatchery Fish

The age of initial food ingestion and the influence of age at initial food presentation on alevin food intake, survival, and subsequent growth were determined for rainbow trout, Salmo gairdneri. Alevins did not show any ingestive behavior nor was any food found in their gut, before initiation of swim-up. The withholding of food from the young fish for some time after swim-up did not impair their ability to learn to feed. Further, the most satisfactory time to initiate exogenous feeding of hatchery fish is when yolk reserves have been completely absorbed, bearing in mind that a considerable quantity of yolk may yet remain in the abdominal cavity after the externally visible yolk sac has disappeared.This study contradicts the hypothesis that delayed feeding of young rainbow trout causes or enhances the likelihood of nonfeeding.

Histogenesis of the oropharyngeal and oesophageal mucosa as related to early feeding in rainbow trout, Salmo gairdneri Richardson

1977 ◽  
Vol 55 (1) ◽  
pp. 116-128 ◽  
Author(s):  
Timothy K. Twongo ◽  
Hugh R. MacCrimmon
Keyword(s):  
Rainbow Trout ◽  
Epithelial Cell ◽  
Alimentary Canal ◽  
Taste Buds ◽  
Salmo Gairdneri ◽  
Mucous Cells ◽  
Early Feeding ◽  
First Feeding ◽  
Oesophageal Mucosa ◽  
Epithelial Layers

The histogenesis of the oropharyngeal and oesophageal mucosa of rainbow trout, Salmo gairdneri, eleutheroembryos was studied from hatching to day 40 in relation to early feeding. Numbers of epithelial layers of the mucosa increased appreciably until day 20 but little thereafter. Differentiation of mucous cells was evident by day 10 and increased rapidly in number until about day 20. The first structurally distinct taste buds were observed in the oropharyngeal mucosa at day 8 and appeared by day 20 to be fully differentiated. An epithelial cell plug that occluded the upper alimentary canal and would have prevented passage of food into the stomach disappeared at about day 17. Teeth, although developing under the mucosa by day 3, had not yet erupted at day 22, the time of first feeding.It is suggested that the onset of first feeding in rainbow trout is in synchrony with the histogenesis of the oropharyngeal mucosa, notably the mucous cells and taste buds. The oropharyngeal mucosa of the fish that failed to feed by day 37 appeared to have undergone extensive hyperplasia while mucous cells were atypical, and taste buds seemingly deformed.

Diel Food Selection by Two Sizes of Rainbow Trout (Salmo gairdneri) in an Experimental Stream

1978 ◽  
Vol 35 (7) ◽  
pp. 971-975 ◽  
Author(s):  
Peter A. Bisson
Keyword(s):  
Rainbow Trout ◽  
Prey Size ◽  
Feeding Activity ◽  
Food Selection ◽  
Salmo Gairdneri ◽  
Invertebrate Drift ◽  
Small Fish ◽  
Drift Density ◽  
Experimental Stream ◽  
Selection Of

The food selected by small (~ 3 g) and large (~ 45 g) hatchery rainbow trout (Salmo gairdneri), studied over a 28-h period, showed that the fish fed selectively, but often on different prey organisms. Feeding activity was highest during daylight hours but was only loosely associated with increases in invertebrate drift density. The majority of large trout exploited adult chironomids on the surface, whereas small trout fed primarily on midwater drift. At night when drift densities were low the limited feeding that took place apparently shifted to bottom foraging. Prey size was the most important factor affecting vulnerability to predation at all hours. Both large and small fish rarely consumed invertebrates < 2 mm long. Selection of larger individuals among certain prey taxa occurred, and in two important groups (Trichoptera and Chironomidae) large trout ate significantly larger prey than did small trout. By being size selective, the trout lost the opportunity to exploit smaller organisms, particularly Collembola, which constituted the bulk of the total drift. Key words: diel habits, drift, predation, rainbow trout, size selection

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