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<br />002795 <br /> <br />in river reaches where stocks have been extirpated. For example, stocking will be required to <br />reestablish the bonytail in the Upper Basin in unoccupied river reaches within their historic range. <br />Propagation and stocking should be considered only as an interim tool in recovery programs since <br />recovery, by definition, implies that the populations or stocks will be self-sufficient (Wydoski 1994a) <br /> <br />The needs associated with large-scale, restoration stocking of hatchery-reared endangered fish to <br />augment wild stocks have not been defined. Some of the unknown factors include the numbers of <br />captive-reared fish to be stocked, the size of the fish at release, location(s) ofreleases, frequency of <br />releases, and habitat requirements of early life stages (Wydoski 1994a). Another factor inherent to <br />the number and size of the captive-reared fish is the amount of hatcherylrearing facilities necessary <br />to rear those fish. <br /> <br />This section presents estimates of the hatcherv/rearing facilities that would be required to support <br />large-scale stocking efforts for each Upper Basin endangered fish species based on varying population <br />densities of adult fish per river mile. These estimates do not account for existing fish populations. <br />The river miles to which the various population densities will be applied reflect the critical habitat <br />reaches designated for each species. For these estimates, razorback sucker survival rates (Wydoski <br />I 996c ) were used for all species in detennining the number of I-year old fish required to produce the <br />various adult fish population densities. <br /> <br />Methodology: <br />In order to gain a better understanding of the facility requirements associated with production of <br />endangered fish for large-scale, restoration stocking, estimates were made beginning with the <br />assumption that recovery would be necessary in all of the designated critical habitat in the upper <br />basin. From this assumption, the number of river miles that would need to be stocked were <br />determined for each species to achieve various population densities of adult fish per river mile. <br />Additional intensive culture facilities may be needed to produce the necessary larvae for each of the <br />species. Using razorback sucker survival estimates published by Wydoski (1996c), the number of 1- <br />year old fish that would be required to produce the various adult population densities was determined. <br />From this number, using estimates found in the Coordinated Hatchery Facility Plan (Wydoski 1994a) <br />ofthe number ofl-year old fish per pound, an estimate could be made of the total weight of the 1- <br />year old fish. An estimate of the required pond space was then found using the assumption that 500 <br />pounds offish can be reared per surface acre during the first growing season (Wydoski 1994a). The <br />results of this process when applied to the Colorado squawfish, bonytail chub, humpback chub, and <br />razorback sucker are described in the following sections. <br /> <br />7.1 Colorado Squawfish <br /> <br />The designated critical habitat for the Colorado squawfish includes portions of the Yampa, Green, <br />White, Gunnison, and Colorado Rivers. As shown in Table 7.1-1, the total required pond area varies <br />from a low of 0.6 acres for an adult population density of 10 fish per mile to 2.2 acres for a density <br />of 40 fish per mile. The table also shows the number oflarvae that would be required to produce the <br />various number of I-year fish. The supporting tables for bonytail chub, humpback chub, and <br />razorback sucker are similar to Table 7.1-1 and are included in Appendix C. <br /> <br />35 <br />