Weight Tables - How Heavy Was That Bowfin?

Using empirical data we obtained and MS Excel Regression analysis, the best formula we have for estimating the weight of a bowfin is G^2*L/780 +0.75 = W, where G is the girth (circumference) in inches, L is the length in inches, and W is the weight in pounds. The prediction factor is 0.96, with 0 meaning the formula doesn't predict the data at all and 1 is a perfect prediction, so we are very close with this formula.The values in Table 1 were calculated with this. The girths we found in our dataset, expressed as a fraction of the length ranged from a low of .42*L to a high of .57*L so I restricted my table to these limits.

Table 1 Length/Girth/Weight Lookup

  Girth (in.) 6.0 7.0 8.0 9.0 10.0 11.0 12.0 13.0 14.0 15.0 16.0 17.0 18.0 19.0 20.0 21.0 22.0 23.0 24.0
Length (in.)                                        
14   1.4 1.6 1.9 2.2                              
14.5   1.4 1.7 1.9 2.3                              
15   1.4 1.7 2.0 2.3                              
15.5   1.5 1.7 2.0 2.4                              
16   1.5 1.8 2.1 2.4                              
16.5   1.5 1.8 2.1 2.5                              
17     1.8 2.1 2.5 2.9                            
17.5     1.8 2.2 2.6 3.0                            
18     1.9 2.2 2.6 3.1                            
18.5     1.9 2.3 2.7 3.1 3.6 4.2                        
19       2.3 2.7 3.2 3.7 4.3                        
19.5       2.3 2.8 3.2 3.8 4.3                        
20       2.4 2.8 3.3 3.8 4.4                        
20.5       2.4 2.9 3.4 3.9 4.5                        
21         2.9 3.4 4.0 4.6                        
21.5         3.0 3.5 4.1 4.7 5.4                      
22         3.1 3.6 4.2 4.8 5.5                      
22.5         3.1 3.6 4.2 4.9 5.6                      
23         3.1 3.7 4.3 5.0 5.7                      
23.5           3.8 4.4 5.1 5.8                      
24           3.8 4.5 5.2 5.9                      
24.5           3.9 4.5 5.3 6.1                      
25           4.0 4.6 5.4 6.2 7.0                    
25.5           4.0 4.7 5.5 6.3 7.1                    
26             4.8 5.5 6.4 7.3 8.2                  
26.5             4.9 5.6 6.5 7.4 8.4                  
27             4.9 5.7 6.6 7.5 8.5                  
27.5             5.0 5.8 6.7 7.7 8.7 9.8 10.9              
28             5.1 5.9 6.8 7.8 8.8 9.9 11.1              
28.5               6.0 6.9 7.9 9.0 10.1 11.3              
29               6.1 7.0 8.0 9.1 10.3 11.5              
29.5               6.2 7.1 8.2 9.2 10.4 11.7              
30               6.3 7.2 8.3 9.4 10.6 11.9              
30.5                 7.3 8.4 9.5 10.7 12.0              
31                 7.5 8.5 9.7 10.9 12.2 13.6            
31.5                 7.6 8.7 9.8 11.1 12.4 13.8            
32                 7.7 8.8 10.0 11.2 12.6 14.0            
32.5                 7.8 8.9 10.1 11.4 12.8 14.2            
33                   9.0 10.3 11.6 13.0 14.4 16.0          
33.5                   9.2 10.4 11.7 13.1 14.6 16.2          
34                   9.3 10.5 11.9 13.3 14.9 16.5          
34.5                   9.4 10.7 12.1 13.5 15.1 16.7 18.4        
35                   9.5 10.8 12.2 13.7 15.3 16.9 18.7        
35.5                     11.0 12.4 13.9 15.5 17.2 18.9        
36                     11.1 12.6 14.1 15.7 17.4 19.2        
36.5                     11.3 12.7 14.3 15.9 17.6 19.4 21.4      
37                     11.4 12.9 14.4 16.1 17.9 19.7 21.6      
37.5                     11.6 13.0 14.6 16.3 18.1 20.0 21.9      
38                       13.2 14.8 16.5 18.3 20.2 22.2 24.3    
38.5                       13.4 15.0 16.7 18.5 20.5 22.5 24.6    
39                       13.5 15.2 16.9 18.8 20.7 22.8 24.9    
39.5                       13.7 15.4 17.1 19.0 21.0 23.1 25.2    
40                         15.6 17.3 19.2 21.2 23.3 25.5 27.8  
40.5                         15.7 17.6 19.5 21.5 23.6 25.8 28.2  
41                         15.9 17.8 19.7 21.7 23.9 26.2 28.5  
41.5                         16.1 18.0 19.9 22.0 24.2 26.5 28.9  
42                           18.2 20.2 22.3 24.5 26.8 29.2 31.7


Table 2 Length/Weight Lookup

A Michigan DNR publication shows this formula for bowfin weight, in pounds and inches: log w = -3.39775 + 2.96004 log L
The table below shows these numbers.
Length (in.) Weight (lb.)
20 2.8
213.3
22 3.8
23 4.3
244.9
25 5.5
266.2
27 6.9
287.7
29 8.5
309.4
31 10.4
3211.4
33 12.5
3413.7
35 14.9
3616.2
37 17.5
3819.0
39 20.5
4022.1
41 23.8
4225.5



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