PERCENTILE PROPORTIONS OF lAKE AND ATLANTIC SALMONS. 



125 



learned what dimensions, if any, do not change their proportions under the aforesaid 

 conditions. The second alternative is impracticable in the present situation since so 

 few specimens have been available and those have lacked uniformity of size and condi- 

 tion. The best that could be done with the material in hand has been to assemble the 

 measurements in groups in such a way as to, as nearly as possible, represent classes of 

 each sex in a number of stages of growth, from parrs to adult breeding salmon. 



In tables 21 and 22, the salmon are represented by 78 lake salmon from the Presump- 

 scot River, Grand Lake, and Sebago Lake, Maine, and 65 Atlantic salmon. 



It is unfortunate that the purity of the Sebago stock is not positive. Many young 

 Atlantic salmon have been introduced from time to time but the result of the introduc- 

 tions is unknown. It is also possible that some of the Presumpscot fish were affected 

 by sea salmon adulteration. However, the Grand Lake salmon can be depended upon 

 for they were all taken before introduction of sea salmon in those waters. But the Grand 

 Lake fish were all taken in the breeding season, therefore, unfortunately, no summer fish 

 are represented. In table 21 eight length classes are denoted as la, 2b, 3c, 4d, 5e, 6f, 

 7g, and 8h, which represent the average lengths of fish not in the breeding season: 

 la, male, Atlantic salmon in parr stage, 214 millimeters (8.4 in.); 2b, Presumpscot male 

 324 millimeters (12.8 in.); 3c, Presumpscot female 337 millimeters (13.2 in.); 4d, Atlantic 

 salmon male 353 millimeters (13.9 in.); 5e, Atlantic salmon female 413 milUmeters 

 (16.3 in.); 6f, Sebago Lake female 416 millimeters (16.5 in.); 7g Atlantic salmon male 

 533 millimeters (21.0 in.); 8h, Sebago Lake male 556 millimeters (21.9 in.). 



While the average proportions of classes of the same length and sex of lake and 

 Atlantic salmon may differ, those of the same sex of different lengths may be alike. In 

 other words there are but few averages of percentile proportions of any length class of 

 the one, which maj' not be found in a different length class of the other. Again classes 

 of the same length may differ in some proportions and not in others. It is not so much 

 the amount of difference in proportions as it is the way they differ that is the most 

 significant. 



f lotal Length \ 



\f dfandard Length 



i Heed- 



'v-- Snout to 

 \5nouftohd^ 

 ^nout^ 



V----^--^ f-Q/f 



Fig. 1. Key drawing explanatory of proportional and comparative measurements used in discussion of variability and 



percentile proportions of lake and Atlantic salmons. 



