Seaward Movement of Coho Salmon (Oncorhynchus kisutch) Fry in Carnation Creek, an Unstable Coastal Stream in British Colombia

1982 ◽  
Vol 39 (4) ◽  
pp. 588-597 ◽  
Author(s):  
G. F. Hartman ◽  
B. C. Andersen ◽  
J. C. Scrivener
Keyword(s):  
Social Behavior ◽  
Coho Salmon ◽  
Rapid Development ◽  
Oncorhynchus Kisutch ◽  
Air Temperatures ◽  
Time Period ◽  
Main Period ◽  
British Colombia ◽  
Downstream Movement

The seaward movement of coho (Oncorhynchus kisutch) fry was monitored over a 10-yr period as a part of a major watershed study. The time period over which downstream movement took place varied widely during different years of study. Coho fry moved seaward earlier, and terminated the main period of movement earlier, following winters in which stream temperatures were warmer. It is presumed that they underwent more rapid development during winters in which stream temperatures were relatively high. Winter stream temperatures were primarily dependent on air temperatures. During seaward movement daily numbers fluctuated widely. Peaks of movement were coincident with or slightly before freshet peaks. In 94 of 122 cases (77%) the number of fry moving seaward during the night of peak discharge, or during the night before, was higher than in any of the three preceding nights. Movement in these cases may have been initiated by rainfall or falling water temperature or a combination of both. Aggressive behavior among coho fry is considered to be an underlying cause of seaward movement. In Carnation Creek, particularly in the early part of the period of seaward movement, the effects of such social behavior on movement patterns may be masked by the effect of freshets and related conditions. By autumn the number of fry remaining in the stream ranged from 9000 to 13 000 over the 10-yr study. Much of the downward adjustment to this resident fry population size occurred after the most active period of seaward movement.Key words: coho fry, social behavior, seaward movement, stream ecology, coho management

Environmental factors influencing freshwater survival and smolt production in Pacific Northwest coho salmon (Oncorhynchus kisutch)

2004 ◽  
Vol 61 (3) ◽  
pp. 360-373 ◽  
Author(s):  
P W Lawson ◽  
E A Logerwell ◽  
N J Mantua ◽  
R C Francis ◽  
V N Agostini
Keyword(s):  
Pacific Northwest ◽  
Air Temperature ◽  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
Stream Flows ◽  
Factors Influencing ◽  
Life Phase ◽  
Air Temperatures ◽  
Queets River ◽  
Marine Survival

Climate variability is well known to affect the marine survival of coho salmon (Oncorhynchus kisutch) in Oregon and Washington. Marine factors have been used to explain up to 83% of the variability in Oregon coastal natural coho salmon recruitment, yet about half the variability in coho salmon recruitment comes from the freshwater life phase of the life cycle. This seeming paradox could be resolved if freshwater variability were linked to climate and climate factors influencing marine survival were correlated with those affecting freshwater survival. Effects of climate on broad-scale fluctuations in freshwater survival or production are not well known. We examined the influence of seasonal stream flows and air temperature on freshwater survival and production of two stock units: Oregon coastal natural coho salmon and Queets River coho salmon from the Washington Coast. Annual air temperatures and second winter flows correlated strongly with smolt production from both stock units. Additional correlates for the Oregon Coast stocks were the date of first fall freshets and flow during smolt outmigration. Air temperature is correlated with sea surface temperature and timing of the spring transition so that good freshwater conditions are typically associated with good marine conditions.

Social interactions of coho salmon (Oncorhynchus kisutch) smolts in seawater

1985 ◽  
Vol 63 (10) ◽  
pp. 2401-2407 ◽  
Author(s):  
Cynthia A. Paszkowski ◽  
Bori L. Olla
Keyword(s):  
Social Behavior ◽  
Social Interactions ◽  
Social System ◽  
Agonistic Behavior ◽  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
Distribution Patterns ◽  
Oregon Coast ◽  
Fish Hatchery ◽  
Free Ranging

The behavior of coho salmon (Oncorhynchus kisutch) smolts was examined under laboratory conditions to determine if the hierarchical–territorial social system characteristic of this species in freshwater persisted in seawater. When held in groups of two to eight fish, hatchery-reared, accelerated underyearling smolts formed hierarchies controlled by a single dominant who was responsible for most of the observed movement, chases, and feeding. Agonistic behavior also occurred within pairs of recently smolted fingerlings from two hatchery stocks with different rearing histories and in groups containing free-ranging fish captured off the Oregon coast. Possible relationships between the observed social behavior and marine distribution patterns of juvenile coho salmon are discussed.

Emigration and Production of Hatchery Coho Salmon (Oncorhynchus kisutch) Stocked in Streams Draining an Old-growth and a Clear-cut Watershed

1987 ◽  
Vol 44 (8) ◽  
pp. 1397-1407 ◽  
Author(s):  
Robert E. Bilby ◽  
Peter A. Bisson
Keyword(s):  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
Old Growth ◽  
Trophic Conditions ◽  
Temperature Changes ◽  
Gross Photosynthesis ◽  
Clear Cut ◽  
Salmon Fry ◽  
Streamflow Change ◽  
Downstream Movement

Downstream movement of coho salmon fry (Oncorhynchus kisutch) stocked in old-growth and clear-cut watersheds occurred in three phases: (1) a brief period of heavy emigration immediately after stocking, (2) relatively little movement throughout most of the summer, and (3) intermittent heavy emigration during early autumn freshets. Coho emigrated whenever a streamflow change ≥ 3%∙d−1 occurred, but movement nearly ceased at flows above a certain level. Temperature changes were less important than discharge in triggering movement. When high densities were stocked, emigrant fry were smaller than residents. When low densities were stocked, emigration after the initial pulse of downstream movement was generally lower and there were no size differences between emigrants and residents. Production in the clear-cut was greater than in the old-growth watershed. Proportionately fewer fish emigrated from the old-growth stream, but when population densities were high, mortality in the old-growth exceeded the clear-cut. Greater emigration from the clear-cut site was possibly related to a scarcity of pools. Although the old-growth stream possessed better rearing habitat, less food may have been available, as suggested by gross photosynthesis rates 50% lower than in the clear-cut stream. Coho production therefore appeared to be most strongly influenced by trophic conditions, while volitional residency was most strongly influenced by habitat quality.

Electrophoretic Variation, Regional Differences, and Gene Flow in the Coho Salmon (Oncorhynchus kisutch) of Southern British Colombia

1987 ◽  
Vol 44 (4) ◽  
pp. 822-831 ◽  
Author(s):  
C F. Wehrhahn ◽  
R. Powell
Keyword(s):  
British Columbia ◽  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
Ice Age ◽  
Enzyme Loci ◽  
Large Populations ◽  
Last Ice Age ◽  
The Mean ◽  
British Colombia ◽  
River Fish

Populations of coho salmon (Oncorhynchus kisutch) in southern British Columbia were assayed for genetic variation at 26 enzyme loci. The mean heterozygosity was only 0.25 ± 0.06%. Previously studied wild Oregon cohos had a mean heterozygosity of 1.36 ± 0.37% compared with 0.30 ± 0.09% in Lower Coastal Mainland and 0.13 ± 0.08% in Upper Fraser River fish for the same enzyme loci. A plausible explanation for the very low mean heterozygosity is that British Columbia coho salmon went through an extreme population bottleneck during or after the last ice age. Lower Coastal Mainland salmon are significantly different from the fish of Vancouver Island and can be easily distinguished from Oregon and Capilano Hatchery (Coastal Mainland, B.C.) fish, it should be feasible to determine the relative proportions of different stocks in large oceanic coho salmon samples. The maximum likelihood estimate of the migration rate between spawning populations is 5.8 ± 1.2 breeding adults per generation. This is enough to prevent adaptation to local habitats by small populations of fewer than 100 breeding adults, but it is not high enough to impede selection in large populations of 1000 or more breeding adults.

Geographic variation in environmental factors regulating outmigration timing of coho salmon (Oncorhynchus kisutch) smolts

2014 ◽  
Vol 71 (1) ◽  
pp. 56-69 ◽  
Author(s):  
Brian C. Spence ◽  
E.J. Dick
Keyword(s):  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
Environmental Cues ◽  
Lunar Phase ◽  
Short Term ◽  
Migration Timing ◽  
Selection Processes ◽  
Favorable Conditions ◽  
Migration Probability ◽  
Downstream Movement

The environmental cues that regulate smoltification and trigger downstream movement by salmon should vary across space in response to differences in the predictability of favorable conditions for migration and ocean entry. To examine this, we modeled the short-term outmigration probability of four coho salmon (Oncorhynchus kisutch) populations in three distinct geographic regions in relation to photoperiod, temperature, streamflow, lunar phase, and interactions among these variables. For smolts in Deer and Flynn creeks, Oregon (1960–1972), migration probability was influenced by numerous factors, including photoperiod, temperature (absolute and change), flow (absolute and change), and lunar phase, with certain factors interacting. Smolts from Carnation Creek, British Columbia (1972–1986) responded to a similarly diverse suite of factors (excluding lunar phase), though in somewhat different ways. In contrast, migration timing of smolts in Sashin Creek, Alaska (1959–1969) was best explained by a model that included only photoperiod, temperature, and the interaction between these terms. These population differences suggest fundamental differences across regions in the selection processes operating in both marine and freshwater environments.

Induced ovulation in coho salmon (Oncorhynchus kisutch). I. Further studies on the use of salmon pituitary preparations

Aquaculture ◽  
1981 ◽  
Vol 26 (1-2) ◽  
pp. 117-127 ◽  
Author(s):  
George A. Hunter ◽  
Edward M. Donaldson ◽  
Helen M. Dye
Keyword(s):  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
Induced Ovulation
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