GREAT LAKES COREGONIDS 



393 



miles ESE. of Milwaukee, Wis., in 60 fathoms (record 10), had 35 per cent; a lift of 

 unknown size, made on September 3, 1920, 22 miles NW. by N. H N. of Michigan 

 City, Ind., in 30 to 40 fathoms, had 29 per cent (record 14); and a lift of 200 pounds, 

 made on August 12, 1920, 15 miles SE. by S. Yi S. of Manistique, Mich., in 60 to 70 

 fathoms, had 40 per cent (record 27). 



The remaining records were made out of Milwaukee, Wis., and Michigan City, 

 Ind., during October and November, either near or on the spawning grounds of the 

 species and in or approximately in the breeding season. On November 15, 1920, 

 a lift of 700 pounds, made 20 miles ESE. of Milwaukee, Wis., in 28 to 35 fathoms, 

 was composed almost exclusively of zenithicus (record 12). Off Michigan City, 

 Ind., a lift of 535 pounds, made on October 11, 1920, 20 miles N. by W. % W., in 30 

 to 40 fathoms, had 44 per cent zenithicus; a lift of 1,000 pounds, made on November 

 8, 1920, 18 miles NNW., in 30 to 38 fathoms, had 54 per cent; a lift of 700 pounds, 

 made on November 19, 1920, 17 miles NNW., in 28 to 32 fathoms, had 15 per cent; a 

 lift of undetermined size, made on November 19, 1920, 10 miles NNW., in 18 fathoms, 

 had 93 per cent; and a lift made on November 19, 1920, 173^ miles NW. by N. % N., 

 in 32 fathoms, had 70 per cent (records 15 to 19). 



The records show nothing clearly about the zone of maximum density for the 

 species. Previous to the spawning season it has been found rare in three lifts at 

 60 fathoms and deeper (records 1, 2, and 24) and to comprise 35 and 40 per cent of 

 two lifts at similar depths (records 10 and 27). In seven lifts at 40 to 65 fathoms 

 it was rare or absent (records 6, 25, and 26, Northport and Charlevoix), and in two 

 others at 30 to 50 fathoms made up 20 and 29 per cent of the lifts (records 3 and 14). 

 (Green Bay records that show chiefly or exclusively artedi and records 20 and 21, 

 made on March 2 and 4, 1921, in 28 to 30 fathoms on the spawning grounds of hoyi, 

 are excepted.) In this connection, it should be pointed out that the records of few 

 short-jawed chubs were made (excepting record 6) in the northern part of the lake, 

 and it is possible that the species is not widely distributed in that section. In the 

 breeding season lifts made between 18 and 40 fathoms in the southern part of the 

 lake had 15 to 99 per cent of zenithicus, the density varying, it is supposed, with 

 the proximity of the nets to the spawning grounds (records 12, 15 to 19.) As the 

 fishermen have learned from experience to conduct their fishing operations for deep- 

 water Leucichthys largely in 60 fathoms or less, it is probable that zenithicus finds 

 its maximum density when not spawning outside the 60-fathom contour. 



BREEDING HABITS 



Fish have been taken on their spawning grounds off Milwaukee, Wis., and Mich- 

 igan City, Ind. Fishermen report a chub spawning off Port Washington, Wis., and 

 Grand Haven, Mich., which from their description appears to be of this species. 

 Doubtless there are breeding grounds in the entire area between Port Washington and 

 Grand Haven and possibly off other ports on the lake. A chub of some sort is said to 

 spawn out of Algoma and Sheboygan, Wis., and Ludington, Mich., but it is not cer- 

 tain from the description of these fish that they are zenithicus. On all grounds spawn- 

 ing takes place on sand and clay at depths of 10 to 30 fathoms, according to the fisher- 

 men, the depth varying with the weather. When the lake is calm the fish come shal- 



