GREAT LAKES COREGONIDS 



367 



Av/V: 



alpenx, (1.2) 1.4-1.7 (1.9), witn 27 per cent more than 1.6. 

 artedi, (1.4) 1.6-1.8 (2.3), with 76 per cent more than 1.6. 

 L/R: 



alpense, (3.8) 4.1-4.4 (4.6), with 20 per cent more than 4.3. 

 artedi, (4.1) 4.3-4.5 (5), with 71 per cent more than 4.3 

 H/M: 



alpense, (2.4) 2.5-2.6 (2.7), with 14 per cent more than 2.6. 

 artedi, (2.5) 2.7-3 (3.3), with 91 per cent more than 2.6. 



H/S: 



alpense, (3.3) 3.4-3.6 (4), with 13 per cent more than 3.6. 

 artedi, (3.3) 3.7-4 (4.4), with 84 per cent more than 3.6. 



Alpense is further separable from artedi by its less elongate body, less pigmentation 

 ■on the body, especially the back and abdominal fins, its usually unpigmented maxil- 

 lary, and by the well-developed and relatively long mandible. Artedi is a much 

 darker fish, with much more pigmented premaxillaries, maxillary, and mandible, and 

 & moderately developed and relatively short mandible. Both species spawn at about 

 the same time, so the state of development of the sex organs is of no assistance in 

 separating the species. 



GEOGRAPHICAL DISTRIBUTION 



My records on the occurrence of this species in Lake Michigan are given in Table 

 20 and are shown platted on the chart in Figure 4. There are 39 records, all but 5 

 of them from specimens personally recorded. From these observations it may be 

 •concluded that the longjaw is generally distributed over the lake where suitable 

 conditions obtain. It is interesting to note that a long-jawed chub is said to have 

 occurred in commercial quantities in the years 1892 to 1894 on the reef in the center of 

 the lake between Port Washington and Muskegon (record 8). While it is probable 

 that this chub was a longjaw, it can not be asserted positively. 



BATHYMETRIC DISTRIBUTION 



Data on the depth range of the longjaw have been collected, for the most part, 

 from the 2% to 2% inch nets that are set in the main lake for chubs, as a rule from 

 30 to 60 or even 90 fathoms, and for herring in Green Bay, where the maximum depth 

 is 24 fathoms. However, longjaws have been taken in every kind of gill net in use 

 and even in pounds. They have been seen from virtually all the examined chub 

 lifts from the lake, the only exceptions being the lifts made on March 24, 1919, in 

 50 fathoms, and on September 24, 1920, in 22 to 25 fathoms, off Milwaukee, Wis. 

 The former lift was made on the spawning grounds of the bloater, and it is not sur- 

 prising that no longjaws were taken. The last obviously was made on poor grounds, 

 as the total lift of all Leucichthys was but 25 pounds. In Green Bay herring alone 

 are taken, except near the mouth of the bay, where the water is deepest; and even 

 bere herring constituted the bulk of the catches made on August 18, 1920. An 

 occasional longjaw was taken in the lift made off Boyer Bluff on Washington Island, 

 Wis., in 18 to 24 fathoms on that date (record 1). 



In the 4 ^2-inch nets that are set for trout in waters of 10 fathoms and deeper, 

 longjaws were seen only on one occasion, namely, on August 11, 1920, 13 miles 

 SE. E. of Manistique, Mich., in 20 fathoms (record 38), though fishermen from 

 94995—29- — -6 



