Graduate Thesis Or Dissertation
 

Geographic variation in timing of fry emergence and smolt migration of coho salmon (Oncorhynchus kisutch)

Public Deposited

Downloadable Content

Download PDF
https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/x059c931f

Descriptions

Attribute NameValues
Creator
Abstract
  • The timing of two events in the early life history of coho salmon--emergence from the gravel and entry into the ocean--is presumed to have evolved to ensure maximum survival during these transition periods. Anthropogenic disturbances may disrupt the timing of these events to the detriment of salmon populations. Multivariate analyses were used to examine regional patterns in downstream migration in relation to environmental variation for 50 smolt populations located between central California and southern Alaska. Significant latitudinal gradients were observed in the timing of the peak of migration, duration of migration, and degree of interannual variation in the peak of migration. Smolt migrations of northern populations generally occurred later in the spring, were shorter in duration, and exhibited lower interannual variability in their timing than did those of southern populations. Some variability in these patterns was associated with watershed characteristics (e.g., elevation, distance from ocean); however, latitudinal patterns transcended this variability and may reflect adaptation to differences in temporal "windows of opportunity" in the ocean environments into which smolts enter. Logistic regression models were used to model within- and between-year variation in probability of smolts migrating during 2-d intervals from four streams in Alaska, British Columbia, and Oregon as a function of time interval, lunar periodicity, temperature (absolute, change, cumulative degree days), and streamflow (absolute, change). Migration probability was positively associated with time, temperature, and change in flow, and negatively associated with absolute flow for at least four of the five data sets examined (P <0.05). Significant, but contradictory, relationships between lunar phase and migration probability were also found. Temperature-based models of embryo and alevin development were coupled with information on stream temperatures to examine regional differences in sensitivity of these life stages to climate warming. Modest stream warming (0.5 to 2.0°C) would substantially accelerate embryo and alevin development, reducing the time between spawning and emergence by two months or more. Changes in development time were predicted to be greatest at higher latitudes and elevations (e.g., Alaska and interior British Columbia), where average incubation temperatures are presently the coldest.
Resource Type
Date Available
Date Issued
Degree Level
Degree Name
Degree Field
Degree Grantor
Commencement Year
Advisor
Committee Member
Academic Affiliation
Non-Academic Affiliation
Subject
Rights Statement
Publisher
Peer Reviewed
Language
Digitization Specifications
  • PDF derivative scanned at 300 ppi (256 B&W, 256 Grayscale, 24-bit Color), using Capture Perfect 3.0.82, on a Canon DR-9080C. CVista PdfCompressor 4.0 was used for pdf compression and textual OCR.
Replaces

Relationships

Parents:

This work has no parents.

In Collection:

Items

Thumbnail Title Date Uploaded Visibility Actions
file details SpenceBrianC1995.pdf 2017-08-01 Public Download