Table G-7 : Formulas to calculate (a) live weight and (b) dry shell weight from shell length and height 

 (mm) for commercial mussel species collected in Reach 15 of the Upper Mississippi River, 

 1994-95. The relationship between weight and shell size was best described by a power 

 regression (y = ax'^b). Equation parameters are as follows: y = dependent variable; x = 

 independent variable; a = y-intercept, b = regression coefficient (slope), r- = coefficient of 

 determination; and n = number of individuals plotted. 



Example : Calculate the live weight and drv' shell weight for fwc Amblema plicata ha\-mg measured shell heights of: 75.10, 

 85.01, 72.52, 76.15, and 91 23 What is the present commercial value of these mussels ($0 86/lb dry shell)? 



Calculations: y = ax^b 



Live weight (g) = (O.OO 13 -75.10^2. 8266)+{0,0013- 85.01 "2. 8266)+(0.0013 ■72.52-2. 8266)*(0 0013- 76.15^2. 8266)+(0,0013- 91, 23"2, 8266) 

 = 260.39 + 369.64 + 235.89 + 270.81 + 451.30 

 = 1588.03 g - 454 g'pound = 3.50 pounds 

 Drj' shell weight (g) =(0.0O13-75.10-2.7444)+C0.0O13-85.0r2.7444)+(0.OO13-72.52-2 7444)*(0.OO13-76.15-2.7444)+(0,0O13-91.23'2 7444) 

 = 182.58 + 256.56+ 165.88+ 189.67 + 311.42 

 = 1106.10 g + 454 g'pound = 2.44 pounds @ S0.86/pound =$2.10 



Page G-8 



Whitney et al., Unionid Sur\ey - Reach 15 UMR 



