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1 1 -7 L 1 1 1 Monitoring; Habitat and In stream flow conditions Estimating population size and relative abundance from year to year will indicate progress towards achieving population size goals. However, other factors must be monitored as well so that population response can be correlated with basin wide management activities and an adaptive and effective approach to management can be implemented. Population viability requires a stable agestructure and recruitment of all life stages. This condition is most easily attained by ensuring that all life history requirements are met. Therefore, the geographic area occupied by the population should be strictly monitored and managed to maintain appropriate habitat and in-stream flow conditions as determined through research. These conditions for the four endangered Colorado River fishes would -include: 1) providing flow regimes necessary to maintain spawning, nursery and adult habitat, such as recommended timing, duration and magnitude of peak flows and designated summer/fall and winter base flows to the extent possible; 2) providing sediment transport and temperature regimes to maintain spawning, nursery and adult habitat to the extent possible; 3) maintaining or improving connectivity among existing populations; 4) maintaining or improving tributary input (both biotic and abiotic); and 5) biotic and abiotic threats, -such as -predation, competition, productivity, pollution, that detrimentally effect population persistence. Although easily defined, maintaining the necessary conditions for population persistence is more difficult. Currently, some information is available to assess these conditions based on basin-wide research; however any newly acquired information-should be incorporated into management objectives as conclusions are determined. The ISW could be the mechanism of acquiring and determining progress and achievement of-population size as well as habitat and in-stream flow conditions if modified to include specific measurements of these important factors. Although habitat and in-stream flow information will not directly provide information on achievement of targeted population sizes, this data must be collected to enable assessment of system response to management activities so strategy effectiveness can be evaluated and modified if necessary. Although it would be most convenient to provide specific values for these habitat conditions at this time, such a designation would be premature in light of ongoing research. Condition values should be specifically designated as they are determined effective through population and system response as measured by ISMP. Population persistence monitoring It is crucial to note that a viable population is not determine singly by numbers of individuals in the population but likewise by persistence (Shaffer 1981; Soule' 1987). After a number of individuals is achieved, the population can only be considered viable if it naturally persists over a period of time. This temporal element of population viability, like the spatial element, can vary depending on life history characteristics of the species and physical attributes of its habitat. One important reason for the necessity of persistence is variability. Populations naturally fluctuate depending on the above mentioned biotic and abiotic variables, hence upon achievement of number of individuals, we can assume numbers will naturally rise and decline. Only over a substantial period of time can the direction of these natural, annual fluctuations be interpreted as a trend. Researchers have offered numbers from 10 to 1000 years as necessary to determine persistence for other species (Shaffer 1981). 27