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<br />-23- <br /> <br />Length and weight data from individual trout can be used to calculate a body <br />condition factor (K) which is a relative measure of robustness, plumpness, or <br />fatness in trout. When the length units are in centimeters (cm) and the <br />weight in grams (g) the formula for "K" is given by the following equation: <br /> <br />K - W(g) x 100/L('m)3 <br /> <br />where W - weight and L - length. Condition factors can be calculated for <br />individual trout species for different stations and years (Lagler 1952). <br />Multiplying the weight by 100 standardizes the K value at 1. A "K" value of <br />one is average, less than one is below average, greater than one above <br />average. K factors provide additional information on changes in the body <br />condition of the trout in the Dolores River over the past 5-6 years. Average <br />condition factors for species and stations between years is presented in Table <br />11. <br /> <br />The body condition factor data indicates (with rare exception) that the <br />average K factors for all three species of trout were higher at all three <br />study sites in 1987 and 1988 than they have been since that time. The only <br />exception is the Metaska site which registered a large increase in 1991. The K <br />factor decreased for all species at all sites in 1989 over 1988. This may <br />indicate food and habitat conditions were less than optimum at that time, <br />given the trout density and biomass in the river (see Tables 2 through 7). <br /> <br />In contrast, K factors were either generally constant or increased slightly <br />after 1989 through 1990 and 1991. However, this fact does not indicate trout <br />habitat conditions have dramatically improved in 1991 compared to 1990. At <br />the two downstream sites, 1991 K factors are as low or lower than they were in <br />1987-1988, despite the fact trout density and biomass are 50%-80% or more <br />below the levels of October 1988 (Tables 2-7). In reality, it is not <br />surprising K factors have increased somewhat in light of the dramatic decrease <br />in density and biomass since October 1989. <br /> <br />Length and weight data collected in April, August, and October 1991 permitted <br />calculation of K factors for the three species of trout at the three sites for <br />the early spring, mid-summer, and early fall 1991 (Table 12). <br />