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

Parasitism on Juvenile Pacific Salmon (Oncorhynchus) and Pacific Herring (Clupea harengus pallasi) in the Strait of Georgia by the River Lamprey (Lampetra ayresi)

1973 ◽  
Vol 30 (4) ◽  
pp. 565-570 ◽  
Author(s):  
J. F. Roos ◽  
P. Gilhousen ◽  
S. R. Killick ◽  
E. R. Zyblut
Keyword(s):  
Size Range ◽  
Pacific Salmon ◽  
Clupea Harengus ◽  
Pacific Herring ◽  
Strait Of Georgia ◽  
Clupea Harengus Pallasi ◽  
River Lamprey ◽  
Juvenile Pacific Salmon ◽  
Healing Wounds ◽  
Narrow Size Range

River lamprey (Lampetra ayresi) were found to parasitize the young of five species of Pacific salmon (Oncorhynchus) and Pacific herring (Clupea harengus pallasi) in the Strait of Georgia, B.C. The dorsal attachment of the river lamprey is in sharp contrast to the usually ventral attachment of other species of lampreys that parasitize salmonids. Up to 1.9% of young salmon showed evidence of lamprey marks, and marked fish were generally restricted to a narrow size-range. Some of the fish exhibited severe wounds. Evidence from healing wounds on fingerlings and scars on adults indicates that some juvenile salmon survive the attacks of the river lamprey.

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

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 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.

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

Temperature-Dependent Maximum Daily Consumption of Juvenile Salmonids by Northern Squawfish (Ptychocheilus oregonensis) from the Columbia River

1991 ◽  
Vol 48 (12) ◽  
pp. 2491-2498 ◽  
Author(s):  
Steven Vigg ◽  
Craig C. Burley
Keyword(s):  
Simulation Modeling ◽  
Pacific Salmon ◽  
Columbia River ◽  
Temperature Dependent ◽  
Daily Consumption ◽  
Preferred Temperature ◽  
Temperature Range ◽  
Juvenile Pacific Salmon ◽  
The Mean ◽  
Ad Libitum Feeding

Maximum daily consumption rate (Cmax as ration or number) of northern squawfish (Ptychocheilus oregonensis) from the Columbia River increased exponentially as a function of temperature. Predator weight did not explain a significant independent proportion of variation in Cmax. The mean maximum daily ration, determined from replicate ad libitum feeding on juvenile Pacific salmon (Oncorhynchus spp.), was 0.47, 0.70, 3.39, and 4.50 cg∙g−1 at 8.0, 12.5, 17.0, and 21.5 °C, respectively. The corresponding mean daily number eaten was 0.50, 1.17, 4.25, and 7.01 prey per predator at the four increasing temperatures. To quantify the temperature-dependent consumption relation, replicate Cmax data within the preferred temperature range were fitted to exponential and exponential sigmoid models. On the basis of a knowledge of thermal relations of northern squawfish, we combined hypothetical Cmax data at temperature extremes with our mean experimental results to fit an algorithm suitable for use in simulation modeling. Both the generalized gamma and biological-rate (Thornton and Lessem. 1978. Trans. Am. Fish. Soc. 107: 284–287) algorithms were suitable to describe a hypothetical temperature–Cmax model over the entire environmental temperature range of 0–27 °C observed in the Columbia River.

Sign in / Sign up

Export Citation Format

Share Document