RESEARCH PAPER Long-term captive breeding does not necessarily prevent reestablishment: lessons learned from Eagle Lake rainbow trout Gerard Carmona-Catot • Peter B. Moyle • Rachel E. Simmons Received: 7 March 2011 / Accepted: 18 July 2011 / Published online: 28 July 2011 Ó Springer Science+Business Media B.V. 2011 Abstract Captive breeding of animals is often cited as an important tool in conservation, especially for fishes, but there are few reports of long-term ( \ 50 years) success of captive breeding programs, even in salmonid fishes. Here we describe the captive breeding program for Eagle Lake rainbow trout, Oncorhynchus mykiss aquilarum, which is endemic to the Eagle Lake watershed of northeastern Califor- nia. The population in Eagle Lake has been dependent on captive breeding for more than 60 years and supports a trophy fishery in the lake. Nevertheless, the basic life history, ecological, and genetic traits of the subspecies still seem to be mostly intact. Although management has apparently minimized negative effects of hatchery rearing, reestablishing a wild population would ensure maintenance of its distinctive life history and its value for future use as a hatchery fish. An important factor that makes reestablishment possible is that the habitat in Eagle Lake is still intact and that Pine Creek, its major spawning stream, is recovering as habitat. With the exception of an abundant alien brook trout (Salvelinus fontinalis) population in Pine Creek, the habitat factors that led to the presumed near-extinction of Eagle Lake rainbow trout in the early twentieth century have been amelio- rated, although the final stages of reestablishment (eradication of brook trout, unequivocal demonstration of successful spawning migration) have still not been completed. The Eagle Lake rainbow trout story shows that long-term captive breeding of migratory salmonid fishes does not necessarily prevent reestablishment of wild populations, provided effort is made to counter the effects of hatchery selection and that natural habitats are restored for reintroduction. Long-term success, however, ultimately depends upon eliminat- ing hatchery influences on wild-spawning populations. Extinction of Eagle Lake rainbow trout as a wild species becomes increasingly likely if we fail to act boldly to protect it and the Eagle Lake watershed. Keywords Salmonidae Á Captive breeding Á Hatchery effects Á Species invasions Á Endangered species Á Conservation Á Eagle Lake Introduction Captive breeding of animals is often cited as an important tool in conservation (Soule ´ et al. 1986), especially for fish (Phillippart 1995). In some cases, it G. Carmona-Catot (&) Á P. B. Moyle Department of Wildlife, Fish and Conservation Biology, University of California, Davis, Davis 95616, CA, USA e-mail: carmona.catot@gmail.com G. Carmona-Catot Institute of Aquatic Ecology, University of Girona, 17071 Girona, Catalonia, Spain R. E. Simmons Department of Animal Science, Genomic Variation Lab, University of California, Davis, Davis 95616, CA, USA 123 Rev Fish Biol Fisheries (2012) 22:325–342 DOI 10.1007/s11160-011-9230-x