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.

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.

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.

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.

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.

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.

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.

scholarly journals Effect of Light Intensity on Initial Survival of Fat Snook (Centropomus parallelus, Pisces: Centropomidae) Larvae

2001 ◽  
Vol 44 (4) ◽  
pp. 343-349 ◽  
Author(s):  
Vinicius Ronzani Cerqueira ◽  
André Macedo Brügger
Keyword(s):  
Light Intensity ◽  
Extreme Values ◽  
Total Darkness ◽  
Larval Rearing ◽  
Swim Bladder ◽  
Complete Darkness ◽  
Light Intensities ◽  
Fat Snook ◽  
Newly Hatched Larvae ◽  
Effect Of Light

Different light intensities were tested during the larval rearing of fat snook (Centropomus parallelus) to evaluate its influence on survival and functional swim bladder rate. Newly-hatched larvae were obtained by stripping of hormonally induced broodstock, and were stocked in 32-liter tanks at densities from 30 to 50 L-1. Four experiments were carried out testing six light intensities: 50, 100, 200, 500, 1500, and 2500 lx, and total darkness as a control. Mean survival ranged from 0.06 to 16.0% and were significantly influenced by light intensity. Complete darkness resulted in 100% mortality after one week, larvae appeared to have starved since they had empty stomachs. The species has the characteristics of a visual-feeder. Survival was the highest at 200 lx, while at 500 lx was higher than at 50, 100, and 2500 lx. Frequency of functional swim bladder ranged from 36.8 to 100%, but it was not significantly correlated with light intensity. Based on this study, a medium light intensity, 200 to 1500 lx, is recommended for rearing fat snook larvae. Extreme values must be avoided, mainly in the first two weeks after hatching.

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