Spatial and interannual variability of juvenile coho salmon growth in the Strait of Georgia (2012-2015)

2020 ◽  
Vol 646 ◽  
pp. 145-160
Author(s):  
ML Journey ◽  
C Neville ◽  
G Young ◽  
M Trudel ◽  
BR Beckman
Keyword(s):  
Growth Factor ◽  
Regional Variation ◽  
Positive Relationship ◽  
Coho Salmon ◽  
Regional Growth ◽  
Oncorhynchus Kisutch ◽  
Fork Length ◽  
Small Scale ◽  
Short Term ◽  
Strait Of Georgia

We conducted a 4 yr (2012-2015) study of regional growth of juvenile coho salmon Oncorhynchus kisutch in the Strait of Georgia (British Columbia, Canada). Size (fork length) and growth (insulin-like growth factor-1 [IGF-1] concentration) varied both regionally and inter-annually. Additionally, we found a positive relationship between IGF-1 concentration and fork length that varied between years, with slopes and y-intercepts higher in 2012 and 2014, respectively, as compared to 2013 and 2015. An ordinal increase of IGF-1 concentration from the south to north in 2012 and 2014 was coupled with an increase in the prevalence of both juvenile herring and juveniles of other fish species in the diet. Across all years, there was a positive relationship between regional mean IGF-1 concentration and regional mean percent of juvenile herring in the diet. Our study demonstrates relatively small-scale spatial heterogeneity in juvenile coho salmon growth that in part, was attributed to regional variation in diet. These findings also demonstrate the utility of short-term growth measures (such as IGF-1) for assessing relatively small-scale spatial and temporal differences in growth.

Changes in Territorial, Gill-flaring, and Feeding Behavior in Juvenile Coho Salmon (Oncorhynchus kisutch) following Short-term Pulses of Suspended Sediment

1985 ◽  
Vol 42 (8) ◽  
pp. 1410-1417 ◽  
Author(s):  
L. Berg ◽  
T. G. Northcote
Keyword(s):  
Feeding Behavior ◽  
Suspended Sediment ◽  
Brine Shrimp ◽  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
Turbid Water ◽  
Short Term ◽  
Dominance Hierarchies ◽  
Short Term Exposure ◽  
Laboratory Stream

The territorial, gill-flaring, and feeding behavior of juvenile coho salmon (Oncorhynchus kisutch) in a laboratory stream was disrupted by short-term exposure to suspended sediment pulses. At the higher turbidities tested (30 and 60 nephelometric turbidity units (NTU)), dominance hierarchies broke down, territories were not defended, and gill flaring occurred more frequently. Only after return to lower turbidities (0–20 NTU) was social organization reestablished. The reaction distance of the fish to adult brine shrimp decreased significantly in turbid water (30 and 60 NTU) as did capture success per strike and the percentage of prey ingested. Implications of these behavioral modifications suggest that the fitness of salmonid populations exposed to short-term pulses of suspended sediment may be impaired.

Natural Mortality Rate in Last Winter of Life of Coho Salmon (Oncorhynchus kisutch) Resident in Puget Sound

1974 ◽  
Vol 31 (6) ◽  
pp. 1158-1160 ◽  
Author(s):  
Stephen B. Mathews ◽  
Raymond Buckley
Keyword(s):  
Mortality Rate ◽  
Coho Salmon ◽  
Puget Sound ◽  
Oncorhynchus Kisutch ◽  
Fork Length ◽  
Natural Mortality

The natural mortality rate during a 3.5-mo period of the last year of life of coho salmon (Oncorhynchus kisutch) resident in Puget Sound was estimated to be 48% of the population at the beginning of this period. This estimate was based on recaptures of 29 fish out of 169, averaging 32 cm in fork length, tagged in January and early February, and 20 out of 61 averaging 41 cm tagged in May and early June, 1970.

Variation in Body Morphology Among British Columbia Populations of Coho Salmon, Oncorhynchus kisutch

1985 ◽  
Vol 42 (12) ◽  
pp. 2020-2028 ◽  
Author(s):  
Eric B. Taylor ◽  
J. D. McPhail
Keyword(s):  
British Columbia ◽  
Coho Salmon ◽  
Function Analysis ◽  
Oncorhynchus Kisutch ◽  
Fraser River ◽  
Strait Of Georgia ◽  
Coastal Streams ◽  
Morphological Differences ◽  
Median Fins ◽  
Coastal British Columbia

Ten populations of juvenile coho salmon, Oncorhynchus kisutch, from streams tributary to the upper Fraser River, the lower Fraser River, and the Strait of Georgia region were morphologically compared. Juveniles from coastal streams (Fraser River below Hell's Gate and the Strait of Georgia) were more robust (deeper bodies and caudal peduncles, shorter heads, and larger median fins) than interior Juveniles. Discriminant function analysis indicated that juvenile coho could be identified as to river of origin with 71% accuracy. Juvenile coho from coastal streams were less successfully classified as to stream of origin; however, juveniles could be successfully identified as either coastal or interior with 93% accuracy. Juvenile coho from north coastal British Columbia, Alaska, and the upper Columbia system also fitted this coastal and interior grouping. This suggests that a coastwide coastal–interior dichotomy in juvenile body form exists. Three populations (one interior and two coastal) were studied in more detail. In these populations the coastal versus interior morphology was consistent over successive years, and was also displayed in individuals reared from eggs in the laboratory. Adult coho salmon also showed some of the coastal–interior morphological differences exhibited by juveniles. We concluded that the morphological differences between coastal and interior coho salmon are at least partially inherited.

Mirror-Elicited Agonistic Behaviour and Body Morphology as Predictors of Dominance Status in Juvenile Coho Salmon (Oncorhynchus kisutch)

1993 ◽  
Vol 50 (3) ◽  
pp. 676-684 ◽  
Author(s):  
L. Blair Holtby ◽  
Douglas P. Swain ◽  
G. Michael Allan
Keyword(s):  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
Fork Length ◽  
Mirror Image ◽  
Large Fish ◽  
Agonistic Interactions ◽  
Dominance Status ◽  
Body Depth ◽  
Body Morphology ◽  
Eventual Dominance

We tested whether body morphology and aggressive behaviour, measured through mirror image stimulation (MIS), could predict the eventual dominance status of juvenile coho salmon (Oncorhynchus kisutch) tested in paired contests and in stream tank interactions with several individuals. Dominance in paired contests was predicted by MIS behaviour on the fifth observation day using newly emerged juveniles and by MSS behaviour on the first observation day using 7-wk-old juveniles. In both.w420020 dstrials, deeper bodied fish tended to be dominant. In the stream tank tests, the MIS behaviour SAM (swim-against-mirror) and fork length were the best predictors of dominance. Large fish with high levels of SAM tended to be dominant. After removing the effects of fish size, neither body depth nor fin size consistently predicted dominance ability. SAM was positively correlated with overt aggressive behaviours in stream tanks but not with lateral displays, juvenile coho salmon appeared to react to conspecifics and to their own mirror images in a quantitatively similar way, and both MIS behaviour and body morphology were significant predictors of the outcome of agonistic interactions among individuals.

Effects of Logging on Size and Age Composition of Juvenile Coho Salmon (Oncorhynchus kisutch) and Density of Presmolts in Southeast Alaska Streams

1989 ◽  
Vol 46 (8) ◽  
pp. 1383-1391 ◽  
Author(s):  
John F. Thedinga ◽  
Michael L. Murphy ◽  
Jonathan Heifetz ◽  
K V. Koski ◽  
Scott W. Johnson
Keyword(s):  
Coho Salmon ◽  
Condition Factor ◽  
Oncorhynchus Kisutch ◽  
Buffer Strips ◽  
Short Term ◽  
Old Growth ◽  
Age Composition ◽  
Southeast Alaska ◽  
Clear Cut ◽  
Northern Regions

Short-term effects of logging on age composition and size of juvenile coho salmon (Oncorhynchus kisutch) were studied in 18 streams in Southeast Alaska in 1982 and 1983; studies were in old-growth and clear-cut reaches with or without buffer strips. The number of fry (age 0) in summer and winter was proportionately higher in buffered and clear-cut reaches than in old-growth reaches, and all treatments averaged a 20% decrease in fry from summer to winter. Fry length and condition factor were greater for buffered and clear-cut reaches than for old-growth reaches, whereas parr (age 1 and older) size did not differ among treatments. Fry and parr were larger in the southern than in the northern regions and their length and weight were directly related to peripbyton biomass and benthos density. A higher percentage of large [Formula: see text] fry remained in buffered reaches than in clear-cut and old-growth reaches; therefore, the density of fry that were potentially large enough to become smolts the next spring (presmolts) was greater in buffered reaches. The larger fry in buffered and clear-cut reaches compared with old-growth reaches was probably due to earlier fry emergence that resulted from increased water temperature.

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