scholarly journals THE OCULAR STRUCTURE, RETINOMOTOR AND PHOTO-BEHAVIORAL RESPONSES OF JUVENILE PACIFIC SALMON

1959 ◽  
Vol 37 (6) ◽  
pp. 965-996 ◽  
Author(s):  
M. A. Ali
Keyword(s):  
Light Adaptation ◽  
Pacific Salmon ◽  
Histological Study ◽  
Retinal Pigment ◽  
Visual Cells ◽  
Ocular Structure ◽  
Short Period ◽  
Juvenile Pacific Salmon ◽  
Poorly Differentiated ◽  
Plexiform Layers

A histological study of the eyes of juvenile sockeye, coho, pink, and chum salmon in fresh water shows that the cones and external nuclear and plexiform layers of the retinae of embryos and alevins are poorly differentiated and do not attain normal histological or physiological proportions until the emergence of fry from the gravel. From a histophysiological study it is evident that only the emerged fry and older stages are capable of retinomotor responses and that these responses become more marked with age. Differences in rates of adaptation are found among the species and stages. Generally, the pigment layer shows a latent period before contraction in dark. Sensitivity to light is independent of the complete light adaptation of the retinal pigment or visual cells, while full acuity of vision is dependent upon the complete light adaptation of cones. Threshold values of cones and rods are indicated by the feeding and schooling responses. At light intensities between the cone and rod thresholds the thicknesses of pigment and cone layers obey the Weber-Fechner law. There is no diurnal rhythm in the positions of retinal pigment and cones of juvenile Oncorhynchus either under constant light or dark. Results are discussed in relation to the migratory, schooling, and feeding behavior. The rapid downstream migration of juvenile salmon during a relatively short period in the night may be related to a semi-dark-adapted state of the eye.

Ultrastructural Changes of Smoooth Endoplasmic Reticulum in the Retinal Pigment Epithelium by Choline Chloride

1972 ◽  
Vol 30 ◽  
pp. 58-59
Author(s):  
Kazushige Hirosawa ◽  
Eichi Yamada
Keyword(s):  
Endoplasmic Reticulum ◽  
Epithelial Cell ◽  
Smooth Endoplasmic Reticulum ◽  
Pigment Epithelium ◽  
Choline Chloride ◽  
Retinal Pigment ◽  
Ultrastructural Changes ◽  
Lower Vertebrate ◽  
Visual Cells ◽  
Pigment Epithelial

The pigment epithelium is located between the choriocapillary and the visual cells. The pigment epithelial cell is characterized by a large amount of the smooth endoplasmic reticulum (SER) in its cytoplasm. In addition, the pigment epithelial cell of some lower vertebrate has myeloid body as a specialized form of the SER. Generally, SER is supposed to work in the lipid metabolism. However, the functions of abundant SER and myeloid body in the pigment epithelial cell are still in question. This paper reports an attempt, to depict the functions of these organelles in the frog retina by administering one of phospholipid precursors.

Assessing estuaries as stopover habitats for juvenile Pacific salmon

2016 ◽  
Vol 559 ◽  
pp. 201-215 ◽  
Author(s):  
JW Moore ◽  
J Gordon ◽  
C Carr-Harris ◽  
AS Gottesfeld ◽  
SM Wilson ◽  
...  
Keyword(s):  
Pacific Salmon ◽  
Juvenile Pacific Salmon

An Electrophysiological Basis for Olfactory Discrimination in Homing Salmon: A Review

1970 ◽  
Vol 27 (3) ◽  
pp. 565-586 ◽  
Author(s):  
Toshiaki J. Hara
Keyword(s):  
Pacific Salmon ◽  
Electrical Response ◽  
High Amplitude ◽  
Polluted Water ◽  
Sensitive Period ◽  
Young Fish ◽  
Spawning Site ◽  
Short Period ◽  
Sign Stimulus ◽  
Spawning Sites

Past and current researches relating to olfactory acuity and discrimination in fishes, with special reference to homing salmon, are reviewed.When the nasal sac of spawning Pacific salmon is stimulated with water from the spawning site a high amplitude electroencephalographic response of characteristic pattern is recorded from the olfactory bulb. This electrical response is specific in the sense that it cannot be evoked by water from spawning sites of other groups of breeding salmon. Further, the salmon respond clearly to water taken from places along their migratory routes below the spawning sites. These findings suggest that olfaction is an important factor in guidance during the final phases of homeward migration of salmon. It is also possible that salmon retrace sequentially a trail of stimuli that is the reverse of that imprinted in the young fish on their seaward migration.Although the available data do not delineate the sensitive period, or the duration of the imprinting process, there is accumulating evidence that only a short period is necessary for imprinting, which may occur when the smolts are in their freshwater life.Recent study on the effect of antimetabolites (puromycin, actinomycin D, or cycloheximide) on olfactory bulbar discrimination in homing salmon suggests that long-term olfactory memory in these fish depends upon continued metabolism of RNA and continued protein synthesis. The possibility that the imprinting process in young fish may be affected by polluted water, which has recently become a serious problem in fisheries, is discussed. The need for electrophysiological as well as biochemical studies at a macromolecular level of the imprinting process is emphasized.Finally, the hypothesis is discussed that a home stream odour may act most effectively as a simple "sign stimulus," which, through the release of a positive rheotropic response, induces the fish to move upstream toward home. This is largely based on the recent experimental observations of the orientation mechanism in several species of teleost fishes.

The Ecology of Juvenile Salmon in the Northeast Pacific Ocean: Regional Comparisons

2007 ◽  
Keyword(s):  
Chinook Salmon ◽  
Sockeye Salmon ◽  
Pacific Salmon ◽  
Gulf Of Alaska ◽  
Juvenile Salmon ◽  
Stomach Fullness ◽  
Feeding Intensity ◽  
Percentage Weight ◽  
Juvenile Pacific Salmon ◽  
Survival Patterns

Abstract.—Upon entering marine waters, juvenile Pacific salmon <em>Oncorhynchus </em>spp. depend on feeding at high and sustained levels to achieve growth necessary for survival. In the last decade, several concurrent studies have been examining the food habits and feeding intensity of juvenile Pacific salmon in the shelf regions from California to the northern Gulf of Alaska. In this paper, we compared results from feeding studies for all five species of juvenile salmon (Chinook salmon <em>O. tshawytscha</em>, coho salmon <em>O. kisutch</em>, chum salmon <em>O. keta, </em>sockeye salmon <em>O. nerka</em>, and pink salmon <em>O. gorbuscha</em>) between 2000 and 2002, years when these regions were sampled extensively. Within these years, we temporally stratified our samples to include early (May–July) and late (August–October) periods of ocean migration. Coho and Chinook salmon diets were most similar due to a high consumption of fish prey, whereas pink, chum, and sockeye salmon diets were more variable with no consistently dominant prey taxa. Salmon diets varied more spatially (by oceanographic and regional factors) than temporally (by season or year) in terms of percentage weight or volume of major prey categories. We also examined regional variations in feeding intensity based on stomach fullness (expressed as percent body weight) and percent of empty or overly full stomachs. Stomach fullness tended to be greater off Alaska than off the west coast of the United States, but the data were highly variable. Results from these comparisons provide a large-scale picture of juvenile salmon feeding in coastal waters throughout much of their range, allowing for comparison with available prey resources, growth, and survival patterns associated with the different regions.

scholarly journals Historical Diets of Forage Fish and Juvenile Pacific Salmon in the Strait of Georgia, 1966–1968

2016 ◽  
Vol 8 (1) ◽  
pp. 580-594 ◽  
Author(s):  
Geoffrey J. Osgood ◽  
Laura A. Kennedy ◽  
Jessica J. Holden ◽  
Eric Hertz ◽  
Skip McKinnell ◽  
...  
Keyword(s):  
Pacific Salmon ◽  
Forage Fish ◽  
Strait Of Georgia ◽  
Juvenile Pacific Salmon

Mechanisms and Meaning of Devries—Rose Adaptation

Perception ◽  
1996 ◽  
Vol 25 (1_suppl) ◽  
pp. 39-39
Author(s):  
K Donner ◽  
P Fagerholm
Keyword(s):  
Light Adaptation ◽  
Ganglion Cells ◽  
Statistical Significance ◽  
Quantum Fluctuations ◽  
Luminance Level ◽  
Square Root ◽  
Visual Responses ◽  
Neural Noise ◽  
Visual Cells ◽  
Mean Luminance

‘Square-root’ or ‘deVries — Rose’ light adaptation is observed over a substantial luminance range in human foveal vision. The classical interpretation is that a detector (presumably in the brain) discriminates the neural signal evoked by the stimulus from the neural noise evoked by quantum fluctuations. It is known, however, that the retina may adjust its gain in inverse proportion to the square root of mean luminance, as observed eg in cat retinal ganglion cells under scotopic or mesopic adaptation. This kind of gain change is approximated even by the primary visual cells, the rods and cones, in at least some vertebrate species up to luminances producing 103 – 104 photoisomerisations per photoreceptor cell, per second. Is square-root adaptation in fact mainly an expression of an inverse-square-root gain in retinal cells? We investigated the roles of gain and noise in human foveal detection of 0.25 deg incremental spots presented for 50 ms on 5 deg steady backgrounds ranging from −0.25 to 2.35 log td, by measuring effects of pixel noise added to the stimulus and background. The results were consistent with the hypothesis that square-root adaptation mainly reflects gain changes, whereas the signal is detected against a constant level of neural noise. They were not consistent with the idea that signals proportional to stimulus intensity are detected against a noise that increases in proportion to quantum fluctuations. Thus, they do not support a simple interpretation of the deVries — Rose law. Still, an inverse-square-root retinal gain may in an evolutionary sense be seen as an adaptation to quantum fluctuations, in view of its functional consequences: (1) that output noise stays constant, independent of luminance level; (2) that light signals of constant statistical significance are encoded by visual responses of constant size.

Seawall as salmon habitat: Eco-engineering improves the distribution and foraging of juvenile Pacific salmon

2020 ◽  
Vol 151 ◽  
pp. 105856 ◽  
Author(s):  
Alexandra C. Sawyer ◽  
Jason D. Toft ◽  
Jeffery R. Cordell
Keyword(s):  
Pacific Salmon ◽  
Juvenile Pacific Salmon
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