392 



BULLETIN OF THE BUREAU OF FISHERIES 



Grand Haven. However, no satisfactory investigations have been made in the 

 latter area, and it is not unlikely that zenithicus occurs there also. It may be stated, 

 then, that zenithicus may be found in suitable conditions throughout Lake Michigan. 



BATHYMETRIC DISTRIBUTION 



The records in Table 28 are made chiefly from the 2% to 2% inch chub nets, 

 which were set during the fishing season in between 12 and 90 fathoms. All the 

 lifts of these nets took at least a few short-jawed chubs, except three lifts in Green 

 Bay (two on August 16, 1920, off Little Sturgeon and 8 miles south of Green Island 

 in 11 and 16 fathoms, respectively, and the other on August 18, 1920, 4 miles west of 

 Bo3^er Bluff in 18 to 24 fathoms), the lift made 5 miles northwest of Cathead Light, 

 Mich., on June 22, 1920, in 40 to 60 fathoms, and the three lifts made off Charlevoix, 

 Mich., on August 10, 11, and 21, 1923, in 35 to 60 fathoms. It is to be noted that 

 the observations out of Milwaukee, Wis., and Michigan City, Ind., which show the 

 fish in the shallowest water, were made on or near the spawning grounds of the 

 species and during the breeding season. 



No specimens have been seen among the small fish casually taken by the 4 to 

 43^2 inch trout and whitefish nets; and in the catches of the l^-inch bait nets set in 

 26 to 40 fathoms, examined at seven ports (see p. 354), only a few individuals 

 were seen at Sheboygan, Wis., on September 28, 1920, and at Port Washington, Wis., 

 on September 25, 1920. 



The data at hand from the commercial chub nets warrant the conclusion that 

 zenithicus in Lake Michigan during the year ranges between the depths of 12 and 

 90 fathoms. It probably does not come into shallower water, at least not during 

 the summer, as none ever have been reported from the herring pound nets that are 

 set out of several ports at depths of less than 10 fathoms. The juvenile individuals, 

 it appears, are not common during the summer at 26 to 40 fathoms, as they were 

 seen seldom in the 13^-inch bait nets. 



RELATIVE ABUNDANCE 



Only the seven lifts of the commercial small-meshed nets mentioned in the 

 preceding paragraph took no zenithicus. Lifts of the chub nets in which only an 

 occasional specimen occurred were made out of Washington Harbor, Wis., on August 

 19, 1920, 20 miles E. y 2 N. of Rock Island, in 71 to 90 fathoms (record 1); off Sturgeon 

 Bay, Wis., on August 23, 1920, 12 miles E. by S. of the ship-channel mouth, in 60 to 

 70 fathoms (record 2); on September 25, 1920, 18 miles E. x / 2 S. of Port Washington, 

 Wis., in 65 to 48 fathoms (record 6); on March 2 and 4, 1921, 21 miles NNW. and 

 15 miles NW. by N. Yz N. of Michigan City, Ind., in 28 to 30 fathoms (records 20 

 and 21); on October 4, 1920, 9 miles north of Point Betsie, Mich., in 60 to 70 fathoms 

 (record 24) ; on July 31, 1923, 5 miles northwest of Cathead Light in 40 to 60 fathoms 

 (record 25); and on June 29, 1920, 5 miles N. by E. of Charlevoix, Mich., in 40 to 55 

 fathoms (record 26). All these lifts were made outside the spawning season of the 

 species. Only four other lifts were examined previous to October 11, and in these 

 the percentage of zenithicus ranged from 20 to 40. A lift of 310 pounds, made on 

 August 24, 1920, 10 miles E. by N. of Algoma, Wis., in 35 to 50 fathoms (record 3), 

 had 20 per cent zenithicus; a lift of 250 pounds, made on September 23, 1920, 27 



