Laserfiche WebLink
<br />Introduction <br /> <br />State and federal wildlife management agencies have been rearing razorback <br /> <br />suckers in captivity since the 1970's (Toney 1974, Hamman 1985) to augment declining <br /> <br />natural populations. Both wild-caught larvae and captive-bred fish are reared at fish <br /> <br />hatcheries and grow-out ponds throughout the southwestern United States (reviewed in <br /> <br />Mueller 2006). Each facility has unique environmental conditions and different rearing <br /> <br />methods which yield different growth rates. Unlike commercial fish species, which have <br /> <br />been cultured and studied extensively, little published information is available on the <br /> <br />effects of various rearing methods on growth of razorback sucker. <br /> <br />Low survival rates of stocked razorback suckers (Brooks 1986, Marsh and Brooks <br /> <br />1989, Marsh and Pacey 2005) have caused target sizes for stocking to steadily increase in <br /> <br />efforts to reduce predation mortality (Marsh et al. 2005, Schooley and Marsh 2007). <br /> <br />Rearing fish to larger sizes comes with increased costs and creates the need to know <br /> <br />. which factors have the greatest impact on growth rate, and how these factors can be <br /> <br />controlled to maximize growth. This document compiles and summarizes information on <br /> <br />current captive rearing practices and associated growth rates for razorback sucker. <br /> <br />We reviewed relevant published literature and agency reports on razorback sucker <br /> <br />to compile background information regarding the effects of environmental factors and <br /> <br />rearing methods on growth. A questionnaire was developed (Appendix 1) and sent to <br /> <br />hatchery managers who rear razorback suckers, Follow up surveys were also conducted <br /> <br />by telephone (Appendix 2). Information on rearing densities, water quality, diseases, and <br /> <br />management practices at each facility were recorded, Site visits to Bubbling Ponds State <br /> <br />Fish Hatchery in Arizona, Dexter National Fish Hatchery in New Mexico, Grand Valley <br /> <br />Endangered Fish Facility in Colorado, Ouray National Fish Hatchery in Utah, and the <br /> <br />5 <br />