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1861 stocking, even though 500,000 larvae were stocked. Reductions in larvae nwnbers, from the stocking site to Lake Powell, suggested that some may have been retained in the river; however, no YOY were found, suggesting that either survival was low or sufficient larvae were not provided for the experiment. It must be remembered that 10 adult female Colorado pikeminnow or razorback sucker can produce 1 million larvae. When the San Juan River has 100 adult females producing 10 times that nwnber of larvae, a reasonable experiment may be conducted. As populations increase and expand upstream to near Fannington, New Mexico, other factors such as diversion dams, temperature, and predation by nonnative species may also become more evident. As nwnbers and range are expanded, more endangered fishes may use habitats where contaminants are a concern. Therefore, just because some factors were not found to be limiting during the 7-year research period does not mean that they will not be limiting at some time in the future. The Monitoring Plan (Propst 2000) developed by the Biology Committee recognizes these concerns and includes continuing assessment of factors that may become future concerns. The only factor that has been eliminated for review during monitoring is fish health. But abnonnalities will continue to be part of the adult fish monitoring protocol, and fish health experts will be added to the monitoring effort if warranted in the future. All biological organisms are limited from infinite population expansion by their environment. Environments have a finite canying capacity that restricts organisma1 population expansion through mechanisrns such as food availability, habitat availability, predation, and competition. Very little infonnation is available regarding the historical abundance of fish species in the San Juan River, but what is available indicates that 3-103 Draft Program Evaluation Report March 2000 .~