Skip to main content

Iteroparity in complex mating systems of steelhead Oncorhynchus mykiss (Walbaum)

Buy Article:

$51.00 plus tax (Refund Policy)


This study investigated diverse reproductive types in complex mating systems of steelhead Oncorhynchus mykiss. Postspawned steelhead (kelts) were sampled during attempted downstream migration over Lower Granite Dam on the Snake River, U.S.A. Multilocus microsatellite genotypes (14 loci) were used to assign unknown origin, kelt individuals to upstream populations of origin. Results indicated that iteroparity is a life-history trait that remains in several tributaries of the Snake River basin despite strong selection against downstream adult passage because of hydroelectric dams. The largest populations of steelhead in the Snake River, however, were only weakly represented (Clearwater River = 7·5% and Salmon River = 9·4%, respectively) in the kelt steelhead mixture relative to the Grande Ronde River (18·2%), Imnaha River (17·4%), Pahsimeroi Hatchery (25·2%) and Asotin Creek (22·2%). A lack of correlation between population escapement size and kelt proportions (P > 0·05) suggests that iteroparity was not uniformly expressed across populations, but was significantly negatively correlated with body size (P < 0·05). Iteroparity may be a valuable source of genetic variability and a conservation priority, especially in years with poor recruitment or in recently bottlenecked populations.

Keywords: Oncorhynchus mykiss; iteroparity; mating systems; semelparity; sex ratio

Document Type: Regular Paper


Affiliations: 1: Columbia River Inter-Tribal Fish Commission, 729 NE Oregon Suite 200, Portland, OR 97232, U.S.A. 2: NOAA Fisheries, NWFSC Montlake Laboratory, Seattle, WA 98112, U.S.A. 3: University of Idaho, Center for Salmonid and Freshwater Species at Risk, 3059-F National Fish Hatchery Road, Hagerman, ID 83332, U.S.A.

Publication date: January 1, 2008


Access Key

Free Content
Free content
New Content
New content
Open Access Content
Open access content
Subscribed Content
Subscribed content
Free Trial Content
Free trial content
Cookie Policy
Cookie Policy
ingentaconnect website makes use of cookies so as to keep track of data that you have filled in. I am Happy with this Find out more