Breeding success of four male life history types of spring Chinook Salmon spawning in an artificial stream Steve L. Schroder & Curtis M. Knudsen & Todd N. Pearsons & Todd W. Kassler & Edward P. Beall & Sewall F. Young & David E. Fast Received: 30 July 2010 / Accepted: 14 March 2011 / Published online: 12 April 2011 # The Author(s) 2011. This article is published with open access at Springerlink.com Abstract In 1997 the Cle Elum Supplementation Research Facility was established to enhance spring Chinook salmon returning to the upper Yakima River, Washington State. This effort increased spring Chinook abundance, yet conditions at the hatchery also signifi- cantly elevated the occurrence of jacks and yearling precocious males. The potential genetic effect that a large influx of early maturing males might have on the upper Yakima River spring Chinook population was examined in an artificial stream. Seven independent groups of fish were placed into the stream from 2001 through 2005. Males with four different life history strategies, large anadromous, jacks, yearling precocious, and sub-yearling precocious were used. Their breeding success or ability to produce offspring was estimated by performing DNA-based pedigree assessments. Large anadromous males spawned with the most females and produced the greatest number of offspring per mate. Jacks and yearling precocious males spawned with more females than sub-yearling precocious males. However, jacks, yearling and sub-yearling precocious males obtained similar numbers of fry per mate. In the test groups, large anadromous males produced 89%, jacks 3%, yearling precocious 7%, and sub-yearling preco- cious 1% of the fry. These percentages remained stable even though the proportion of large anadromous males in the test groups ranged from 48% to 88% and tertiary sex ratios varied from 1.4 to 2.4 males per female. Our data suggest that large anadromous males generate most of the fry in natural settings when half or more of the males present on a spawning ground use this life history strategy. Keywords Spring Chinook salmon . Jacks . Precocious males . Breeding success . Relative breeding success Introduction Life history strategies in fishes are defined by rates of juvenile development, age of sexual maturation, offspring production, levels of parental investment, Environ Biol Fish (2012) 94:231–248 DOI 10.1007/s10641-011-9789-z S. L. Schroder (*) : T. W. Kassler : S. F. Young Washington Department of Fish and Wildlife, 600 Capitol Way North, Olympia, WA 98501–1091, USA e-mail: schrosls@dfw.wa.gov C. M. Knudsen Oncorh Consulting, 2623 Galloway SE, Olympia, WA 98501, USA T. N. Pearsons Grant County Public Utility District, P.O. Box 878, Ephrata, WA 98823, USA E. P. Beall Institut National de la Recherche Agronomique, 64 310 Saint Pée Sur Nivelle, France D. E. Fast Yakama Nation, P.O. Box 151, Toppenish, WA 98948, USA