GREAT LAKES COREGONIDS 



369 



fathoms; August 10, 1923, 8 miles NNW. and on August 21, 1923, from an unknown 

 locality off that port (records 24, 32, 34, and 36). At Michigan City, Ind., a lift 

 made on September 3, 1920, 22 miles NW. by N. y 2 N. in 30 to 40 fathoms, had 10 

 per cent (record 11); on October 11, 1920, 20 miles N. by W. % W., in 30 to 40 

 fathoms, had 20 per cent (record 12); on November 8, 1920, 18 miles NNW. in 30 to 

 38 fathoms, 33 per cent (record 13); on November 19, 1920, 17 miles NNW., in 28 

 to 32 fathoms, 30 per cent (record 14); and 17^ miles NW. by N. % N., 15 per cent 

 longjaws (record 15). (Records 16, 17, and 18 for this port, in which few longjaws 

 were found, were made on or near the spawning grounds of zenithicus and hoyi.) 



The evidence indicates that the longjaw occurs most abundantly at the north- 

 eastern end of the lake between Frankfort, and Manistique, Mich., where the usual 

 depth of the water is less than 70 fathoms. In this area it has been found to com- 

 prise 22 to 98 per cent of the hauls and has been taken in the l^-inch bait nets and in 

 the 43^-inch trout nets. A second area of abundance lies off Michigan City, Ind., 

 at the southern end of the lake, where the water is not over 40 or 50 fathoms deep. 

 It has been found here to comprise 10 to 33 per cent of the lifts of the chub nets. 

 Chub lifts made at other places on the lake at depths of 18 to 90 fathoms took few 

 longjaws, but the data are too inconclusive to determine finally the abundance of the 

 fish there. Longjaws, according to a fisherman, formerly occurred abundantly on 

 the reef in the center of the lake between Port Washington and Muskegon, where the 

 chart shows a minimum depth of 38 fathoms. It appears, then, that the maximum 

 density of the longjaw population when not spawning is between 28 and 70 fathoms 

 only where a depth of 70 fathoms is attained in the vicinity of shallow water. Only 

 stragglers have been found shallower or deeper. 



BREEDING HABITS 



No breeding fish have been seen, and the time and places of spawning are known 

 only from inference and the testimony of fishermen. Female specimens taken on 

 November 19, 1920, 17 miles NNW. and 17^ miles NW. by N. % N. of Michigan 

 City, Ind., showed well-developed but not ripe ova, and the males showed pearl 

 organs. The fish certainly would spawn soon and probably in the vicinity. The 

 fishermen say that at the north end of the lake longjaws come ashore toward the 

 end of October and spawn during November at depths of about 10 to 25 fathoms. 

 Known spawning grounds are situated off the east shore of Beaver Island and in Big 

 and Little Traverse Bays (records 27, 30, 31, and 37). The bottom visited is 

 composed of mud or clay mixed with rock, according to the fishermen. Chubs of 

 some kind spawn off Leeland, Mich., in November at 10 to 25 fathoms, according to 

 Walter Wilson of Northport; off Manistee, Mich., at the same time, but no shallower 

 than 40 fathoms, according to Charles Henrickson, sr., of Charlevoix, Mich.; and 

 off Ludington and Muskegon, Mich., at the same time in 20 fathoms, according to 

 Will DeYoung and the Vanderberg brothers, respectively. The fishermen are unable 

 to describe these spawning fish, and as nothing is known of the composition of the 

 chub lifts made out of these ports during other seasons, it can not be stated that these 

 fish are longjaws. Other spawning grounds for the species, aside from those definitely 

 known, probably could be found. 



