Age and Vision as Factors in Bottom Colour Selection by Rainbow Trout, Salmo gairdneri

1969 ◽  
Vol 26 (3) ◽  
pp. 687-693 ◽  
Author(s):  
Wen-hwa Kwain ◽  
Hugh R. MacCrimmon
Keyword(s):  
Rainbow Trout ◽  
Light Intensity ◽  
Visible Light ◽  
Total Darkness ◽  
Salmo Gairdneri ◽  
Colour Discrimination ◽  
Significant Preference ◽  
Light Intensities ◽  
Behavioural Patterns ◽  
Normal Fish

Rainbow trout exposed in a circular tank to a choice of black or white bottom at a light intensity of 10−2 lux were randomly distributed until the age of 14 months at which time a significant preference for black began and became more pronounced with increasing age.Groups of fish (18–24 months of age) with normal eyes, without eye lenses, and lacking eyes, were held in total darkness and at 10−2, 10, and 200 lux. In total darkness all groups were randomly distributed and quiescent. Fish without eye lenses selected black at all visible light intensities and acted similarly to normal fish at 10−2 lux. Fish lacking eyes were randomly distributed and more-or-less inactive at all intensities.The eye is essential for bottom colour discrimination and behavioural patterns occurring in normal trout exposed to different light intensities.

Use of Overhead Cover by Rainbow Trout Exposed to a Series of Light Intensities

1966 ◽  
Vol 23 (7) ◽  
pp. 983-990 ◽  
Author(s):  
Hugh McCrimmon ◽  
Wen-Hwa Kwain
Keyword(s):  
Rainbow Trout ◽  
Light Intensity ◽  
Positive Response ◽  
Total Darkness ◽  
Salmo Gairdneri ◽  
Light Intensities

Fingerling and yearling trout (Salmo gairdneri Richardson) responded differently when exposed to a series of artificial daylight illuminations. Fingerling trout showed no apparent response to the overhead cover, being randomly distributed at all light intensities. Yearling trout, except in total darkness, exhibit a positive response to the overhead cover, but their pattern of behaviour differed with the light intensity and the positioning of the cover.

Embryonic Development, Early Growth, and Meristic Variation in Rainbow Trout (Salmo gairdneri) Exposed to Combinations of Light Intensity and Temperature

1975 ◽  
Vol 32 (3) ◽  
pp. 397-402 ◽  
Author(s):  
Wen-hwa Kwain
Keyword(s):  
Rainbow Trout ◽  
Embryonic Development ◽  
Mortality Rates ◽  
Early Growth ◽  
Development Rate ◽  
Salmo Gairdneri ◽  
Initial Weight ◽  
Light Intensities ◽  
Incubation Periods ◽  
Meristic Variation

Lowest mortality rates of rainbow trout (Salmo gairdneri) embryos were obtained at temperatures of 7 and 10 C and light intensities of 0.2 and 20 lx. Temperatures of 3 and 15 C and an intensity of 400 lx were near the thresholds for development. Eggs exposed to 0.2 lx required 111 days to reach 50% hatch at 3 C, but 26 days at 15 C; those exposed to 20 lx, 97 days at 3 C and 25 days at 15 C.Growth rates of rainbow trout 145 days after hatch were significantly different (P < 0.05) at 10 and 3 C, and 20, 2, and 0.2 lx. The fastest growth occurred at 10 C and 2 lx, and the lowest growth at 3 C and 0.2 lx. For increment of body weight it was about 23.8%/day of initial weight and 6.6% at 3 C. At light intensities of 20, 2, and 0.2 lx, the rate per day was 24.7, 17.2, and 11.2%, respectively. However, increases in length occurred at a much reduced rate.Variations in numbers of vertebrae, gill rakers, and fin rays were positively correlated with the embryonic development rate. Longer incubation periods were usually associated with more meristic elements, regardless of the environmental factors involved.

DESCRIPTION OF A BACTERIUM ASSOCIATED WITH REDMOUTH DISEASE OF RAINBOW TROUT (SALMO GAIRDNERI)

1966 ◽  
Vol 12 (4) ◽  
pp. 763-770 ◽  
Author(s):  
A. J. Ross ◽  
R. R. Rucker ◽  
W. H. Ewing
Keyword(s):  
Rainbow Trout ◽  
Taxonomic Position ◽  
Salmo Gairdneri ◽  
Gram Negative ◽  
The Family ◽  
Normal Fish

A description was given of a gram-negative, peritrichously flagellated, fermentative bacterium that was isolated on numerous occasions from kidney tissues of rainbow trout (Salmo gairdneri) afflicted with redmouth disease. Although the bacteria apparently were members of the family Enterobacteriaceae, it was impossible to determine their taxonomic position within the family with certainty. Hence it was recommended that their taxonomic position remain sub judice for the present. As a temporary designation RM bacterium was used.Redmouth disease was transmitted from infected to normal fish through the medium of water.

Factors Affecting Rainbow Trout (Salmo gairdneri) Predation on Migrant Fry of Sockeye Salmon (Oncorhynchus nerka)

1976 ◽  
Vol 33 (1) ◽  
pp. 19-24 ◽  
Author(s):  
R. M. Ginetz ◽  
P. A. Larkin
Keyword(s):  
Rainbow Trout ◽  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Development Stage ◽  
Salmo Gairdneri ◽  
Factors Affecting ◽  
Light Intensities ◽  
Salmon Fry ◽  
Lower Stream ◽  
Downstream Movement

Predation of rainbow trout (Salmo gairdneri) on migrant sockeye salmon (Oncorhynchus nerka) fry in experimental streams was higher on fry at an earlier development stage, in moonlight by contrast to cloudy night light intensities, at lesser turbidities, and at lower stream velocities. At dusk light intensities, from.05 to.30 ft-c, mortality from predation was inversely related to light intensity. The longer the period of exposure of fry to naturally declining light intensities prior to downstream movement, the lower was the loss to predators. Exposure of predators to high light intensities prior to the downstream movement of fry resulted in decreased fry mortality. Fry that had survived exposure to predators in an experimental stream 1 and 2 days previous were less vulnerable to predation than "naive" fry. Successive exposures further decreased the loss to predation. Fry enumerated at a counting fence suffered less predation than fry not enumerated. Experienced fry moved downstream more rapidly than naive fry.In laboratory aquaria, experienced fry formed compact schools prior to and in response to stimuli, while naive fry formed loose schools or did not school. Experienced fry were less active in responding to stimuli. Enumerated fry resembled experienced fry; nonenumerated fry resembled naive fry.Various techniques of enhancing sockeye salmon fry survival during downstream migration are suggested by these results.

Further Observations on the Response of Rainbow Trout, Salmo gairdneri, to Overhead Light

1969 ◽  
Vol 26 (12) ◽  
pp. 3233-3237 ◽  
Author(s):  
Wen-hwa Kwain ◽  
Hugh R. MacCrimmon
Keyword(s):  
Rainbow Trout ◽  
Salmo Gairdneri ◽  
Artificial Light ◽  
Significant Preference ◽  
Minimum Light ◽  
Light Minimum ◽  
Overhead Light

The response of rainbow trout (Salmo gairdneri Richardson) to overhead light changed with the growth of the fish. No response was evident until the age of 7 months, after which the response became more pronounced with age. Trout exhibited a significant preference for the darkest chamber when given a choice of five intensities of artificial light. Minimum light threshold for 10-month-old fish was between 0.01 and 0.005 lux. However, 24-month-old fish had a lower level of light threshold between 0.005 and 0.001 lux.

Influence of light on early development and meristic characters in the rainbow trout, Salmo gairdneri Richardson

1969 ◽  
Vol 47 (4) ◽  
pp. 631-637 ◽  
Author(s):  
H. R. MacCrimmon ◽  
Wen-Hwa Kwain
Keyword(s):  
Rainbow Trout ◽  
Light Intensity ◽  
Metabolic Rate ◽  
Early Development ◽  
Salmo Gairdneri ◽  
Artificial Light ◽  
Meristic Characters ◽  
Fin Rays ◽  
Test Light ◽  
Pelvic Fin

Initial mortality of newly fertilized rainbow trout eggs incubated in artificial light increased with intensity. The mortality among eyed eggs exposed to the same set of conditions was comparatively low regardless of intensity. Mortality, time to hatch, metabolic rate, and the number of vertebrae formed correlated positively with visible light intensity but only during the pre-eyed stage of incubation. By contrast, the numbers of dorsal and anal fin rays were affected by light intensity during the posteyed incubation period, the greatest number of rays on these fins occurring in fish incubated at light intensity of 10 lux. The numbers of pectoral and pelvic fin rays were constant at all test light intensities. Further research is imperative if the importance of light as an environmental factor in the early development of fish is to be understood.

Electrical Responses of the Olfactory Bulb of Pacific Salmon Oncorhynchus nerka and Oncorhynchus kisutch

1972 ◽  
Vol 29 (9) ◽  
pp. 1351-1355 ◽  
Author(s):  
Toshiaki J. Hara
Keyword(s):  
Rainbow Trout ◽  
Pacific Salmon ◽  
Oncorhynchus Nerka ◽  
Threshold Concentration ◽  
Salmo Gairdneri ◽  
Olfactory Responses ◽  
Amino Acid Solutions ◽  
Normal Fish ◽  
Different Sources ◽  
Electrical Responses

Olfactory bulbar electrical responses elicited by nasal infusion of food extracts, hand rinse, and several amino acid solutions were studied in sockeye (Oncorhynchus nerka) and coho (O. kisutch) salmon from several different sources. Comparison was also made in rainbow trout (Salmo gairdneri). Significant variations in the olfactory bulbar responses were observed among different species and even among the same species from different sources. The estimated lowest threshold concentration for L-serine was between 10−6 and 10−7 M in salmon. Olfactory responses of rainbow trout were always several times larger than those of salmon.Pretreatment of nasal cavity with 10−4 M solutions of HgCl2 or CuSO4 (27 or 16 mg/liter, respectively) for 10 sec completely blocked the olfactory responses in all fish species studied. The effect was reversible; the responses returned to their original level by rinsing. Exposure of fish to 0.1 mg/liter HgCl2 for up to 3 days reduced the olfactory responses to 40–10% of those of normal fish. CuSO4 was the more toxic.

Effect of DDT on Discriminating Ability of Rainbow Trout (Salmo gairdneri)

1975 ◽  
Vol 32 (6) ◽  
pp. 785-788 ◽  
Author(s):  
Patricia G. McNicholl ◽  
W. C. Mackay
Keyword(s):  
Rainbow Trout ◽  
Light Intensity ◽  
Salmo Gairdneri ◽  
Discriminating Ability

Rainbow trout (Salmo gairdneri) trained to discriminate between a bright (723 lx) and a dim (22 lx) light were tested to determine the minimum difference in light intensity they could distinguish before and 71 h after being given DDT orally at 0, 30, 50, and 80% of the LD50 dose. Discriminating ability decreased linearly with increased dose, while performance and retention were unaffected.

scholarly journals ADULT TRIPLOIDS IN A RAINBOW TROUT FAMILY

Genetics ◽  
1979 ◽  
Vol 93 (4) ◽  
pp. 961-973 ◽  
Author(s):  
Gary H Thorgaard ◽  
Graham A E Gall
Keyword(s):  
Rainbow Trout ◽  
Y Chromosome ◽  
Sexual Maturation ◽  
Fish Culture ◽  
Salmo Gairdneri ◽  
External Appearance ◽  
Hatchery Stock ◽  
Normal Fish ◽  
Production Losses

ABSTRACT Six triploid individuals were found in a full-sib family of 11 adult rainbow trout (Salmo gairdneri) from a domesticated hatchery stock. The triploid individuals were normal in size and external appearance, had underdeveloped gonads, and showed no evidence of 3n/2n chimerism or mosaicism. XXY triploids were males, suggesting that the Y chromosome is male determining in trout. Because they may avoid production losses associated with sexual maturation in normal fish, triploid trout and salmon could potentially be useful in fish culture.

Response of rainbow trout (Salmo gairdneri) embryos to current flow in simulated substrates

1985 ◽  
Vol 63 (8) ◽  
pp. 1813-1815 ◽  
Author(s):  
Christopher P. Nunan ◽  
David L. G. Noakes
Keyword(s):  
Rainbow Trout ◽  
Current Flow ◽  
Movement Patterns ◽  
Artificial Substrate ◽  
Total Darkness ◽  
Salmo Gairdneri ◽  
Normal Movement ◽  
Emergent Behaviour

Direction of current flow did not affect the movement patterns of rainbow trout embryos maintained in artificial substrate systems. Embryos successfully emerged from the substrate in total darkness, although light has previously been implicated as necessary for emergent behaviour. Neither phototactic or rheotactic behaviour appears necessary for "normal" movement and emergence of salmonid embryos. Movement patterns appear to be primarily due to geotactic–geokinetic behaviour.

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