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.

Effect of Metopirone on Pituitary–Interrenal Function in Two Teleosts, Sockeye Salmon (Oncorhynchus nerka) and Rainbow Trout (Salmo gairdneri)

1968 ◽  
Vol 25 (7) ◽  
pp. 1465-1474 ◽  
Author(s):  
Ulf H. M. Fagerlund ◽  
J. R. McBride ◽  
Edward M. Donaldson
Keyword(s):  
Rainbow Trout ◽  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Inhibitory Effect ◽  
Salmo Gairdneri ◽  
Pars Distalis ◽  
Marked Inhibitory Effect ◽  
Interrenal Cells ◽  
Rostral Region ◽  
Low Dosage

Metopirone (SU 4885), an inhibitor of 11β-hydroxylation of adrenocorticosteroids, was administered intramuscularly to adult castrated sockeye salmon (Oncorhynchus nerka) and intact rainbow trout (Salmo gairdneri). Marked hypertrophy of interrenal cells pointed to an increase in the activity of the interrenal tissue of both species. Increased cortisol concentrations in trout at low dosage levels of metopirone suggested that the drug was stressful. However, decreased concentrations at higher dosage levels in trout, and decreased cortisol concentrations in all salmon indicated that the drug was also exerting a marked inhibitory effect on 11β-hydroxylation. In salmon, a repository ACTH preparation (acthar) brought about interrenal hypertrophy similar to that produced by metopirone. Metopirone also induced degranulation and hyperplasia of the cells of the palisade-like layer in the rostral region of the pars distalis in both species of fish. These cells were the only cell type of the pars distalis that were stained with lead-haematoxylin. The evidence indicates that they are the corticotrops.

Density, growth, and change in density of coho salmon and rainbow trout in three Lake Michigan tributaries

1983 ◽  
Vol 61 (5) ◽  
pp. 1120-1127 ◽  
Author(s):  
L. M. Carl
Keyword(s):  
Rainbow Trout ◽  
Growth Rates ◽  
Lake Michigan ◽  
Coho Salmon ◽  
Daily Growth ◽  
Salmon Fry ◽  
Daily Change ◽  
Early Fall ◽  
Growth And Change ◽  
Downstream Movement

Coho salmon spawning peaked in the late fall. Spawning densities ranged from fewer than 5 coho salmon per hectare up to 90 fish per hectare. Subyearling coho salmon densities ranged from 10 to 60 fish per 100 m2 in June and dropped to 5–20 fish by early fall. Coho salmon fry increased in length from 40 mm in early May, to over 120 mm by smolt out-migration in the following April. Coho salmon instantaneous daily change in density coefficients ranged from 0.004 to 0.019 and were dependent on initial coho density. Daily coho salmon growth rates ranged from 0.38 to 0.60 mm per day and were not dependent on initial coho salmon density. Downstream movement of rainbow trout fry began in May, and continued into July. In the spring 10–20 yearlings and one to five 2-year-olds per 100 m2 were present. Most fry emerged in June at a size of 25 mm and grew to 85 mm by fall. Daily growth rates varied from 0.23 to 0.45 mm per day for yearling rainbow trout and were not correlated with rainbow trout density.

Occurrence of the eyefluke, Diplostomum (Diplostomum) baeri bucculentum Dubois et Rausch, 1948, in salmonid fishes of northern British Columbia

1985 ◽  
Vol 63 (2) ◽  
pp. 396-399 ◽  
Author(s):  
Hilda Lei Ching
Keyword(s):  
Rainbow Trout ◽  
Chinook Salmon ◽  
Sockeye Salmon ◽  
Lake Trout ◽  
Infected Fish ◽  
Salmo Gairdneri ◽  
Coregonus Clupeaformis ◽  
Lake Whitefish ◽  
Dolly Varden Salvelinus Malma ◽  
Prosopium Williamsoni

As a result of experimental infections in chicks, diplostomula found in the retina of chinook salmon from the Nechako River were identified as Diplostomum (Diplostomum) baeri bucculentum. Eyeflukes in other salmonids were considered to be the same species based on similar measurements and site in the eyes. These eyeflukes varied in prevalence and mean intensity in seven salmonid species surveyed in nine localities in 1979–1981. The following fish were sampled: rainbow trout (Salmo gairdneri), 505; mountain whitefish (Prosopium williamsoni), 334; lake whitefish (Coregonus clupeaformis), 32; Dolly Varden (Salvelinus malma), 66; lake trout (S. namaycush), 13; kokanee or sockeye salmon (Oncorhynchus nerka), 323; and chinook salmon (O. tshawytscha), 164. Eyeflukes had prevalences ranging from 84 to 100% in six lakes, 64% in the river, 53% in one reservoir site, and a prevalence of 15% in the other reservoir site. Mountain and lake whitefishes had high mean intensities while kokanee had low mean intensities. Correlation of increased intensity with increased fish size was significant for 6 of 27 samples. Four samples of lake whitefish, mountain whitefish, rainbow trout, and chinook salmon showed significant asymmetry when numbers of diplostomula were compared between eyes. More of the heavily infected fish showed asymmetry than did the lightly infected fish.

scholarly journals Pigmentation of salmonids: Factors affecting carotenoid deposition in rainbow trout (Salmo gairdneri)

Aquaculture ◽  
1985 ◽  
Vol 46 (2) ◽  
pp. 133-142 ◽  
Author(s):  
Ole J. Torrissen
Keyword(s):  
Rainbow Trout ◽  
Salmo Gairdneri ◽  
Factors Affecting

Differential Response to Water Current by Two Homozygous LDH Phenotypes of Young Rainbow Trout (Salmo gairdneri)

1981 ◽  
Vol 38 (3) ◽  
pp. 348-352 ◽  
Author(s):  
T. G. Northcote ◽  
B. W. Kelso
Keyword(s):  
Rainbow Trout ◽  
Lactate Dehydrogenase ◽  
Differential Response ◽  
Water Current ◽  
Salmo Gairdneri ◽  
Migratory Behavior ◽  
Current Response ◽  
Upstream Migration ◽  
Response To Water ◽  
Downstream Movement

Above-waterfall, wild stocks of rainbow trout fry homozygous for liver lactate dehydrogenase alleles ldh HαA and ldh HαB were artificially propagated, and their response to water current was compared in experimental channels permitting upstream or downstream movement. Although HαA HαA phenotypes showed significantly more upstream movement than HαB HαB phenotypes in tests made under lighted conditions and less downstream movement in darkness, these differences in behavior cannot necessarily be ascribed to the ldh Hα locus. Implications to control of current responses in trout maintaining populations above waterfalls impassible to upstream migration are discussed.Key words: current response, LDH, rainbow trout, migratory behavior

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.

The Pigments of Salmon

1937 ◽  
Vol 3 (5) ◽  
pp. 469-472 ◽  
Author(s):  
Basil E. Bailey
Keyword(s):  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Salmo Gairdneri ◽  
Carotenoid Pigments ◽  
Red Pigments ◽  
Red Muscle

The red colour of the muscle flesh of the sockeye salmon (Oncorhynchus nerka) is due to the presence of two carotenoid pigments both of which have properties similar to those of astacin. Two red pigments were also found in the red muscle flesh of the steelhead salmon (Salmo gairdneri).

Long-term changes in rearing habitat and downstream movement by juvenile sockeye salmon (Oncorhynchus nerka) in an interconnected Alaska lake system

2008 ◽  
Vol 17 (3) ◽  
pp. 443-454 ◽  
Author(s):  
P. A. H. Westley ◽  
R. Hilborn ◽  
T. P. Quinn ◽  
G. T. Ruggerone ◽  
D. E. Schindler
Keyword(s):  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Lake System ◽  
Long Term Changes ◽  
Downstream Movement

Daily Growth Rings in the Otoliths of Juvenile Sockeye Salmon (Oncorhynchus nerka)

1980 ◽  
Vol 37 (10) ◽  
pp. 1495-1498 ◽  
Author(s):  
K. H. Wilson ◽  
P. A. Larkin
Keyword(s):  
British Columbia ◽  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Growth Rings ◽  
Daily Growth ◽  
Salmon Fry

Sockeye salmon fry were collected from the Fulton River spawning channel at Babine Lake, British Columbia, in May 1978. The fish were reared for 26 d in enclosures in the spawning channel and were sampled every 7 to 10 d. The sagittae were removed from 25 fish from each sample, and the growth rings in one otolith from each fish were counted. A regression of the number of rings on the number of days since capture showed that these rings are, on average, formed daily, beginning at the time of emergence. A number of possible technical and biological causes of variation in ring counts within and between samples are considered.Key words: otolith, sagittae, daily growth rings, sockeye salmon fry

Sign in / Sign up

Export Citation Format

Share Document