Graduate Thesis Or Dissertation
 

Distribution and survival of coho salmon fry after emigration from natal streams

Public Deposited

Downloadable Content

Download PDF
https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/p8418r605

Descriptions

Attribute NameValues
Creator
Abstract
  • Large numbers of coho salmon (Oncorhynehus kisutch) fry move downstream shortly after emergence from the gravel in many spawning tributaries. In three small coastal streams of Oregon about eight times more juveniles leave the tributaries as newly emerged fry than as smolts one year later. Because these early emigrants comprise such a large proportion of the total out-migration of juvenile coho from these streams, a study was initiated to determine their distribution and survival and to evaluate their contribution, if any, to the spawning escapements. In spring 1972, all emigrating coho fry were marked with ventral finclips as they entered fish traps located near the mouths of the three natal streams. Coho fry were later examined for ventral marks in July and September at 19 sampling stations in downstream areas. Emigrants generally dispersed downstream after being marked, although some upstream movement occurred once they entered-larger tributaries. A few moved as far as 9.7 km downstream from the fish traps. Few, if any, migrated directly to saltwater. The proportion of emigrants in samples of coho fry was highest directly below the fish traps and decreased farther downstream. Emigrant fry were not evenly distributed-in downstream areas. About 7% of the emigrants survived to September. Survival rates of emigrant fry and of fry In downstream areas that had not emigrated from the study streams (residents)were similar from July to September, being 43% and 46%, respectively. The survival of coho that remained above the traps was 78% for the same time period. The evidence suggests emigrants were as competitive as residents in downstream areas, but that environments downstream were more adverse than those farther upstream. Eight adult and jack coho salmon that had been marked as emigrating fry in spring 1969, returned to spawn in the natal streams in 1970-71 and 1971-72. They represented a known return of about 0.1% of the emigrants. Emigrant fry probably contributed to spawning escapements in downstream areas as well, but contributions to these areas could not be directly evaluated.
Resource Type
Date Available
Date Issued
Degree Level
Degree Name
Degree Field
Degree Grantor
Commencement Year
Advisor
Academic Affiliation
Non-Academic Affiliation
Subject
Rights Statement
Publisher
Peer Reviewed
Language
Digitization Specifications
  • File scanned at 300 ppi (Monochrome) using Capture Perfect 3.0.82 on a Canon DR-9080C in PDF format. 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 LindsayRobertBryan1974.pdf 2017-08-19 Public Download