Night Feeding of Brown and Rainbow Trout in an Experimental Stream Channel

1969 ◽  
Vol 26 (12) ◽  
pp. 3275-3278 ◽  
Author(s):  
Thomas M. Jenkins Jr.
Keyword(s):  
Rainbow Trout ◽  
Salmo Trutta ◽  
Salmo Gairdneri ◽  
Mountain Stream ◽  
Stream Channel ◽  
Fish Feeding ◽  
Feeding Tubes ◽  
Night Feeding ◽  
Terrestrial Insects ◽  
Experimental Stream

This study sought to determine if stream-living brown and rainbow trout (Salmo trutta and Salmo gairdneri) will feed on drifting terrestrial insects at night. Groups of fish were confined in segments of a rocky-substrate mountain stream, and marked ants were introduced to the current from observation towers equipped with feeding tubes. After the last introductions of an experiment, the fish were removed and their stomachs were examined for marked ants.Although fish of both species fed at night, they appeared to take a smaller percentage of the ants provided than did day-feeding groups studied for comparison. Fish feeding under bright moonlight and starlight captured introduced ants at about the same rates. The results suggest that trout in the type of stream studied feed or are in feeding readiness at nearly all hours of the day or night, at least in the summer months.

Feeding of Rainbow Trout (Salmo gairdneri) in Relation to Abundance of Drifting Invertebrates in a Mountain Stream

1970 ◽  
Vol 27 (12) ◽  
pp. 2356-2361 ◽  
Author(s):  
T. M. Jenkins Jr. ◽  
G. V. Elliott ◽  
C. R. Feldmeth
Keyword(s):  
Rainbow Trout ◽  
Salmo Gairdneri ◽  
Mountain Stream ◽  
Benthic Insects ◽  
Important Prey ◽  
Night Feeding ◽  
Generally True

Hatchery-reared rainbow trout, deprived of food for 48 or 96 hr and released in a mountain stream for 5- or 10-hr periods, consumed aerial invertebrates in numbers loosely associated with their seasonal and hourly abundance in the drift. The same was generally true for benthic insects, except that on several days feeding was much poorer relative to drift from 3:00 AM to 8:00 AM than at other times of day.In September and October tests, aerial forms were abundant during daylight, and benthic forms abundant at night, enabling trout to feed 24 hr a day. Day and night feeding in September were roughly equal in importance, but in October more food was taken during the day. Aerial invertebrates were so rare in December that benthic insects were the most important prey day and night. However, even benthics were not numerous enough to provide good feeding.

Selection by Young Rainbow Trout (Salmo gairdneri) in Simulated Stream Environments For Live and Dead Prey of Different Sizes

1983 ◽  
Vol 40 (10) ◽  
pp. 1745-1749 ◽  
Author(s):  
J. R. Irvine ◽  
T. G. Northcote
Keyword(s):  
Rainbow Trout ◽  
Salmo Gairdneri ◽  
Live Prey ◽  
Feeding Experience ◽  
Wide Range ◽  
Experimental Stream ◽  
Dead Prey

Underyearling rainbow trout (Salmo gairdneri) in experimental stream tanks presented with live and dead prey preferred live prey. Trout fry generally were size selective predators and previous feeding experience did not affect the size of prey consumed. When a wide range of prey sizes was offered, larger trout fry fed upon bigger prey than did smaller fry. Cyclops were underrepresented in trout fry stomachs relative to Daphnia of similar size.

Bacterial Kidney Disease in Feral Populations of Brook Trout (Salvelinus fontinalis), Brown Trout (Salmo trutta), and Rainbow Trout (Salmo gairdneri)

1979 ◽  
Vol 36 (11) ◽  
pp. 1370-1376 ◽  
Author(s):  
Douglas L. Mitchum ◽  
Loris E. Sherman ◽  
George T. Baxter
Keyword(s):  
Rainbow Trout ◽  
Kidney Disease ◽  
Brown Trout ◽  
Brook Trout ◽  
Salmo Trutta ◽  
Salmo Gairdneri ◽  
Age Classes ◽  
Bacterial Kidney Disease ◽  
Live Fish ◽  
Brown Trout Salmo Trutta

Incidence and effects of bacterial kidney disease (BKD) were determined in wild, naturally reproducing populations of brook trout (Salvelinus fontinalis), brown trout (Salmo trutta), and rainbow trout (Salmo gairdneri) in a small lake and stream system in southeastern Wyoming, USA where BKD epizootics have been observed since 1972. During 1976, dead fish were collected at three upstream stations, and 60 live fish were collected from each of 11 stations. All fish were necropsied, and virological, bacteriological, and parasitological examinations were conducted by standard methods. An indirect fluorescent antibody technique was used to detect the BKD organism in cultures and kidney tissue smears. Bacterial kidney disease was diagnosed in 100% of the dead brook trout collected. Incidence among live fish ranged from 83% at an upstream station to only 3% at the most downstream location, and was highest in brook trout and lowest in rainbow trout. Two longnose suckers (Catostomus catostomus), the only non-salmonids collected, were found negative for BKD. Clinical signs of infection and the most severe infections were found only in brook trout. Five age-classes of feral brook trout were involved in the epizootics. Since other known pathogens were essentially absent, it is believed that all deaths were due to BKD. Relationships between species susceptibility to BKD, age-classes, water chemistry and water temperatures, and certain ecological conditions are discussed. Key words: bacterial kidney disease, feral trout, epizootics, brook trout, brown trout, rainbow trout

Observations on the life-cycle of the strigeoid trematode, Apatemon (Apatemon) gracilis (Rudolphi, 1819) Szidat, 1928

1976 ◽  
Vol 50 (2) ◽  
pp. 125-132 ◽  
Author(s):  
David Blair
Keyword(s):  
Life Cycle ◽  
Rainbow Trout ◽  
Salmo Trutta ◽  
Fish Host ◽  
The Body ◽  
Salmo Gairdneri ◽  
Stone Loach ◽  
Experimental Conditions ◽  
Pericardial Cavity ◽  
Wide Range

AbstractThe life-cycle of Apatemon (A.) gracilis was completed in the laboratory. The snail host is Lymnaeaperegra (Müller). The cercaria is redescribed from a wide range of material. Metacercariae were found in naturally infected rainbow trout (Salmo gairdneri Richardson), three-spined sticklebacks (Gasterosteus aculeatiis L.) and stone loach (Nemacheilus barbatulus (L.)) from Scotland and in three-spined sticklebacks from Iceland. In trout, most metacercariae were found in the pericardial cavity, in sticklebacks, the eye, and in loach, the body cavity. In infection experiments, cercariae from naturally infected Scottish snails developed in threespined sticklebacks, rainbow trout and brown trout (Salmo trutta L.). Under experimental conditions cercariae did not penetrate stone loach, although this species is naturally infected with A gracilis. The phenomenon of fish host specificity is briefly discussed. Development of the metacercaria is described. Excystation of metacercarial cysts with pepsin and trypsin solutions is unlike that reported for any other digenean; the contents of the cyst appear to be under pressure. In pepsin, layers of the cyst wall peel back from one end. When transferred to trypsin, one pole of the cyst ruptures and the worm is forcibly expelled.

Effects of Illumination on Behavior of Wild Brown (Salmo trutta) and Rainbow Trout (Salmo gairdneri) Exposed to Black and White Backgrounds

1973 ◽  
Vol 30 (12) ◽  
pp. 1875-1880 ◽  
Author(s):  
John A. Ritter ◽  
Hugh R. MacCrimmon
Keyword(s):  
Rainbow Trout ◽  
Salmo Trutta ◽  
Salmo Gairdneri ◽  
White Background ◽  
Activity Levels ◽  
Sudden Increase ◽  
Experimental Tank ◽  
Protective Response ◽  
Black And White ◽  
Selection Of

Wild brown (Salmo trutta) and rainbow trout (Salmo gairdneri) placed in a circular tank illuminated at 10−2 lx immediately selected black rather than white background. Preference for black fluctuated with activity during the first 2 hr while both selection of black and activity gradually decreased with habituation over the following 84 hr. A sudden increase in illumination to 200 lx reestablished the strong selection of black which decreased rapidly with rising activity. Selection of black was inversely correlated with activity of the fish and was greater under moving than nonmoving water conditions. Differences in activity levels between rainbow and brown trout caused minor differences in response to background.Temporal preference for black background is interpreted as a protective response to the fright stimuli of initial handling, unfamiliarity with the experimental tank, and sudden increase in illumination. Duration of the response after the sudden increase in illumination was less in brown than rainbow trout. Because of its influence on activity and selection of light or dark backgrounds, light is an important ecological factor for trout.

An Estimate of Energy Expenditure by Rainbow Trout (Salmo gairdneri) in a Small Mountain Stream

1973 ◽  
Vol 30 (11) ◽  
pp. 1755-1759 ◽  
Author(s):  
C. Robert Feldmeth ◽  
Thomas M. Jenkins Jr.
Keyword(s):  
Rainbow Trout ◽  
Energy Expenditure ◽  
Beat Frequency ◽  
Live Weight ◽  
Time Of Day ◽  
Salmo Gairdneri ◽  
Mountain Stream ◽  
Natural Food ◽  
Published Data ◽  
Natural Stream

A method is presented which estimates energy expended by rainbow trout (Salmo gairdneri) in a natural stream habitat. Swimming speeds were determined by counting caudal fin beat frequency in the field. Published data on metabolic rates estimated in a water tunnel respirometer were then used to calculate energy expenditure.Swimming speeds and hence energy expenditure did not vary statistically for time of day or night (overall means: swimming speed, 16.1 cm/sec; energy expenditure, 736.5 cal/kg per hour). Our calculations indicate that swimming at 16 cm/sec would cost a 100-g rainbow trout 53 cal/hr at 15 C, and about 0.48 g (live weight) of natural food per 6 hr would be needed to offset the cost of swimming.

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