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, '1')016[/9 CHAPTER 3: RESULTS OF THE 7 -YEAR RESEARCH PROGRAM INTRODUCTION The research projects undertaken by the SJRIP were aimed, in one way or another, at either determining factors limiting recovery of the two endangered fish species or developing strategies to reduce or eliminate limiting factors. Factors limiting recovery are those environmental conditions that prevent a population from increasing to a level where it is genetically viable, self- sustaining, and threats to its existence are removed. A population is self-sustaining when it can maintain itself indefinitely through natural reproduction. This chapter discusses how the SJRIP addressed each of the potential limiting factors, the findings regarding the importance of these limiting factors, and proposals to reduce or alleviate important limiting factors. Emphasis is placed on the two endangered fish species, although other components of the native fish community are discussed where appropriate. Final research reports, as noted in Table 2.1, are cited extensively, as are portions of the Flow Report, which synthesized results of the 7-year research plan as they relate to flow recommendations. While flow recommendations were primarily developed to address the limiting factor of habitat, they may also be important in addressing other limiting factors. In addition to research on the San Juan River, results and conclusions from relevant research in other portions of the Colorado River Basin are included. The SJRIP studies addressed five broad categories oflimiting factors. Initially, habitat limitation, including flow issues and reductions in range, was one of the major factors addressed. Reduced amounts of suitable habitat, presumably resulting from unnatural flow regimes, was a major reason why reoperation of Navajo Dam was part of the recovery program. Other limiting factors that received initial attention included interactions among endangered species and nonnative fishes, and chemical (contaminant) issues. As studies progressed, fish health was identified as a potential concern, and studies were added to address that issue. It was later recognized that populations of both endangered species in the San Juan River were too small to respond to improvements in their habitat within the time frame of the 7 -year research period, and population size was recognized as a limiting factor. Detailed methods used in SJRIP studies are not presented in this document, unless that information is pertinent to the discussion. Detailed methods can be found in each ofthe final research reports that are cited throughout this document' and available from the SJRIP (http://southwest.fws.gov/sjrip). Summary reports (Holden and Masslich 1995, I 997a, I 997b) also detail the general methods and results of ongoing research efforts. September 2000 3-1 Program Evaluation Report