Age, Growth, and Lief History of Klamath River Basin Steelhead Trout (Oncorhynchus mykiss irideus) as Determined from Scale Analysis

Document Details:

Title: Age, Growth, and Lief History of Klamath River Basin Steelhead Trout (Oncorhynchus mykiss irideus) as Determined from Scale Analysis
Category: Technical Report
File: Hopelain_1998_0350_Age-growth-and-life-history-of-Klamath-basin-steelhead.pdf
Updated Date: 20.06.2017
Author(s)/Source(s): James S. Hopelain─▒
Publication Date: 1998
Focal Topic: Steelhead/Rainbow Trout
Location: Klamath Basin
Watershed Code: 180102
Abstract:

AduIt steeIhead (Oncorhynchus mykiss irideus) scales were analyzed from eight fall-run, two spring-run, and one winter-run stocks within the Klamath-Trinity River system, from 1981 through 1983, to provide basic information on age, growth, and life history. The higher degree of half-pounder occurrence of upper KIamath River steelhead stocks (86.7 to 100%) compared to Trinity River steelhead stocks (32.0 to 80.0%) was the major life history difference noted in scale analysis. Early life history was similar for all areas sampled with most juveniles (86.4%) remaining in freshwater during the first two years of life before migrating to sea. Repeat spawning ranged from 17.6 lo 47.9% for fall-run, 40.0 to 63.6% for spring-run, and 31.1% for winter-run steelhead. Mean length of adults at first spawning was inversely related to percent half-pounder occurrence in each stock. Ages of returning spawners, back calculated lengths at various life stages, and growth information are presented.

Keyword Tags:
Steelhead, Life History, Scale Analysis