Downstream movements and angler catches of 2 strains of planted yearling rainbow trout (Salmo gairdneri) were monitored for 2 years in a small Oregon stream, Mill Creek. The Roaring River strain showed a tendency for rapid downstream movement, while the Cape Cod strain tended to remain in the planted area for a longer period and were also caught in higher numbers. As many as 37.2 percent of the Roaring River trout moved out of the stream, compared to a maximum of 18.2 percent of the Cape Cod trout. J. WILDL. MANAGE. 42(2):329-333 Downstream movements of rainbow trout following stocking, have been reported widely in the literature. Migration tendencies have been attributed to condition of fish, streamflow, water temperature, physical features of streams, and available food. Although comparative studies relating to genetic differences in stocks have been undertaken (Butler and Borgeson 1965, Ratledge and Cornell 1953, Hansen and Stauffer 1971), only limited studies (e.g., Cordone and Nicola 1970) have indicated downstream movements were due to genetic characteristics of hatchery stocks. But, Needham and Behnke (1962) speculated that many modern hatchery brood stocks were primarily derived from a mixing of resident rainbow x resident cutthroat, together with anadromous steelhead trout. Behnke now believes (pers. comm., 14 March 1977) that the original McCloud River hatchery rainbow trout brood stock was derived from crossing native redband rainbow trout with anadromous steelhead trout. Due to steelhead outbreeding, a downstream movement tendency may be inherent in a portion of long established hatchery brood fish. A primary objective of stocking catchable trout is to provide recreational fishing in heavily used areas, where natural production cannot meet demand. Fish that move out of these areas soon after planting can be considered to be an economic loss to this objective. Preliminary data by the Oregon Department of Fish and Wildlife, in 1974, led to the testing of the hypothesis that there were behavioral differences between 2 strains of hatchery-reared rainbow trout, Roaring River (widely used in Oregon) and Cape Cod (widely used in Washington). The general hypotheses tested in 1975 and 1976 were: H1--that downstream movements of Roaring River trout were significantly different from Cape Cod trout following stocking; and H2-that angler catches of Roaring River trout were significantly different from Cape Cod trout in the planted area. We wish to acknowledge the cooperation of William Wingfield and his assistants at Roaring River Hatchery, Oregon Department of Fish and Wildlife. Partial funding of this research came from Federal Aid in Fish Restoration Act (DingellJohnson) funds through the U.S. Fish and Wildlife Service, Project F-94-R. We thank Dr. R. Behnke for historical information and theories on rainbow trout brood stocks. Thanks are due K. A. Moring J. Wildl. Manage. 42(2):1978 329 This content downloaded from 207.46.13.149 on Mon, 03 Oct 2016 05:45:10 UTC All use subject to http://about.jstor.org/terms 330 DOWNSTREAM MOVEMENT OF STOCKED TROUT *Moring and Buchanan and J. Ehmke for editorial assistance, and Drs. H. H. Wagner and J. Watson for critically reviewing the manuscript.