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Potential benefits of the Chute Falls translocation The speculated potential gains in establishing fish above Chute Falls would be to: 1) achieve a demographic boost in the main LCR population, 2) expand the range of the species, and 3) contribute to a self-sustaining wild population. The potential demographic gain can be roughly estimated by considering that since 2001 there has been an average of 740 humpback chub ~ 200 mm residing in the lower 14.2 km of the LCR during the fall (Van Haverbeke 2004). Assuming that these fall abundance estimates are representative of year round residence, this translates into an average of 52 humpback chub> 200 mm per km of river. Considering that there may be an additional 6 km of potential habitat above Chute Falls, this translates into a potential demographic gain of 312 fish> 200 mm (i.e., 4+ year old fish of presumed breeding age). This represents a potential increase to the presumed resident adult portion of the LCR population of -30%. Alternatively, using the average estimate since 2001 for the abundance of humpback chub ~ 200 mm (1,631 fish; Van Haverbeke 2004), this translates into a 16% demographic boost, more representative of the LCR population as a whole. Thus, the potential demographic increase resulting from the translocation could be viewed as a positive conservation measure from a demographics standpoint. On the other hand, it also suggests that the founder population may have some power to influence the genetics of the LCR population. Regardless, the above illustrates that should a group of reproductively isolated humpback chub establish above Chute Falls, it is probably destined to remain small (i.e., Ne < < 500). In addition to a demographic gain, the proposed action offers the potential to expand the current range of the species in the LCR by - 5 km. Speckled dace are sampled up to about one km below Blue Springs (Mattes 1993), suggesting that km 20 may be the uppermost reach that humpback chub would be expected to survive. Nevertheless, a 5 km expansion would represent a 25% increase in available LCR habitat for humpback chub. Unfortunately, expansion into this rangeshould not be expected to function as a refuge from catastrophic loss in the LCR (e.g., toxic spill into the LCR from upstream). Finally, a successful translocation has potential to further promote a humpback chub population that is self-sustaining, as required in the current Recovery Goals for the species (USFWS 2002a). Therefore, it may be advisable to continue with this action prior to enacting other potential options. Recommendations for the translocated fish above Chute Falls The translocation effort above Chute Falls should be accompanied by long-term commitments to manage and monitor these fish. Such commitments may include mark- recapture efforts, maintaining an appropriate level of bi-directional gene flow, monitoring genetic aspects of the fish both above and below Chute Falls (particularly changes in heterozygosity), and monitoring the algal and invertebrate communities above and below Chute Falls. 40