370 



BULLETIN OF THE BUREAU OF FISHERIES 



H/S: 



Michigan, (3.3) 3.4-3.6 (4). 

 Huron, (3.1) 3.3-3.6 (3.8). 

 Pv/P: 



Michigan, (1.6) 1.9-2.2 (2.5). 

 Huron, (1.6) 1.8-2.1 (2.3). 

 Av/V: 



Michigan, (1.2) 1.4-1.7 (1.9). 

 Huron, (1.3) 1.4-1.7 (1.9). 



Leucichthys alpenae of Lake Huron 



The Lake Huron longjaw closely resembles that of Lake Michigan in appearance. 

 A comparison of the principal systematic characters is given below : 



Gill rakers on the first branchial arch: 



Michigan, (33) 36-43 (46) 



Huron, (31) 34-40 (44) ™ 

 Lateral -line scales: 



Michigan, (71) 78-85 (96). 



Huron, (70) 76-83 (91). 

 L/H: 



Michigan, (3.8) 4.1-4.4 (4.6). 

 Huron, (3.6) 4-4.3 (4.4). 

 H/E: 



Michigan, (3.8) 4.2-4.6 (5.2). 

 Huron, (4) 4.5-4.9 (5.2). 



It appears that Huron specimens have somewhat fewer gill rakers on the first 

 branchial arch, fewer lateral-line scales, a somewhat larger head, and a smaller eye. 

 The L/H ratio is the more significant that the Huron specimens average decidedly 

 larger, and it is usual that the head is proportionally smaller on larger fish. The eye 

 changes so markedly in comparative size with the growth of the individual that the 

 specimens from the two lakes can not be compared satisfactorily for this character. 



The color in life is as in the Lake Michigan form. Pigmentation is about as in 

 the form of northern Lake Michigan. 



Males taken on the spawning grounds in Colpoy Bay on December 3, 1919, 

 show pearl organs. The degree of development of these pearls varies with the indi- 

 vidual, and in the individual the development on the two sides is often unequal. 

 In general, however, the development of the breeding adornment is about like that 

 of joliannx described on page 350. 



VARIATIONS 



Racial variations. — The longjaw is generally distributed throughout Lake Huron 

 and Georgian Bay, and there are probably several distinct schools in these areas. 

 A comparison of fish from the commercial takes of Lake Huron with those of Georgian 

 Bay, and of small fish from Lake Huron taken in less than 60 fathoms with those 

 taken from 60 fathoms or deeper, indicates that on the basis of my material it is 

 not possible to established any definite characteristics for any of these races. 



Size variations. — Small specimens differ from large ones chiefly in proportions. 

 Counts of gill rakers, however, show fewer rakers on the first branchial arch in small 

 specimens. They number (31) 33-37 (41) as compared with (31) 37-40 (44) in 

 larger specimens. The head in specimens less than 210 millimeters in length is 

 slightly larger, contained (3.4) 3.8-4.1 (4.2) times in the total length, as compared 

 with (3.6) 4-4.3 (4.4) for large fish. The eye is conspicuously larger in the first 

 class. The ratios for the head divided by the eye are (3.6) 3.8-4.1 (4.4) and (4) 



27 These figures for Lake Michigan are based on an examination of 383 specimens, those for scales on 329, those for H/S on 73; 

 all others are based on an examination of 289 specimens, ranging in length from 205 to 386 millimeters. 



> 8 These and succeeding figures for Lake Huron, except those for gill rakers and lateral-line scales, are given for 177 specimens, 

 ranging in length from 210 to 368 millimeters. The figures for gill rakers are based on 417 specimens of all sizes, those for scales on 

 323 specimens. 



