PROPOSED REVISION OF THE STANDARD-WEIGHT EQUATION FOR RAINBOW-TROUT

We developed standard-weight equations for rainbow trout by applying t he regression-line-percentile (RLP) technique to samples from 81 lotic and 50 lentic populations from across North America. Because the leng th-weight relationship differed between lotic and lentic fish populati ons, we developed separate equations for those populations. They are l og(10)W(s) = -5.023 + 3.024log(10)TL (lotic) and log(10)W(s) = -4.898 + 2.990log(10)TL (lentic), where W, is the standard weight in grams an d TL is the total length in millimeters. The equivalent English-unit l otic and lentic RLP equations are log(10)W(s) = -3.432 + 3.024log(10)T L and log(10)W(s) = -3.354 + 2.990log(10)TL, respectively, where W-x i s the standard weight in pounds and TL is the total length in inches. Computed W-r values using the RLP equations did not systematically cha nge with increasing fish length. Significant differences in W-r were n ot observed between samples from lotic and lentic populations or among length categories when our RLP equations were used.