GREAT LAKES COREGONIDS 



397 



a maximum depth of 28 fathoms for the channel, and as this species has been taken 

 in water as shallow it is possible that it may be present here. 



Georgian Bay. — From Georgian Bay a gilled specimen was found among the 

 chubs taken on November 6, 1917, off Wiarton, Ontario, in 45 to 60 fathoms; and 

 on July 30, 1919, out of Lions Head, Ontario, in 60 fathoms two small individuals 

 were found ensnarled in the netting. Though no specimens have been seen among 

 the samples taken from five other lifts, not including those made on the spawning 

 grounds of the longjaw, it is possible, nevertheless, that zenithicus occurs throughout 

 the bay and that the nets are not set in the proper locations or possibly are of too 

 large mesh to capture it. 



From these data it appears that zenithicus probably is found throughout Lake 

 Huron proper and possibly throughout Georgian Bay at depths of 14 to 100 fathoms, 

 but that it has not yet been recorded from the North Channel. 



BATHYMETRIC DISTRIBUTION 



The table shows zenithicus to have been taken in the 2% and 3 inch chub nets 

 at depths of 35 to 100 fathoms. In less than 35 fathoms its occurrence has been 

 established only by means of the 4^-inch trout nets, the 2%-inch chub nets that 

 were set under my direction with the trout gangs, and the l^-inch bait nets. The 

 43^-inch nets brought in specimens in 1917 on September 7, 10 (two boats), 12, 

 14, and 22, and on July 10, 1923 (records 9, 11, 12, 13, 14, 22, and 35). The box 

 of 224-inch nets set with the 43^-inch gangs off Alpena, Mich., on September 17, 

 1917, 133^ miles SE. by S. of the can buoy in 15 fathoms (record 16); on September 

 19, 1917, 23 miles SE. by E. y 2 E. of the can buoy in 30 fathoms (record 19); and on 

 September 26, 1917, 13 miles SE. by S. of the city in 17 fathoms (record 23) brought 

 in zenithicus. However, none were caught in the box of nets lifted on November 

 2, 1917, 7 miles ENE. of the can buoy in 15 fathoms. The 1 ^2-inch bait nets in 

 about 30 fathoms took specimens at Cheboygan, Mich., on October 15, 1919 (record 

 4), at Alpena, Mich., on September 8, 1917, and September 16, 1919 (records 10 and 

 29), and at Harbor Beach, Mich., on March 15, 1919 (record 37). From these data 

 it appears that at least during late summer and early fall zenithicus ranges at depths 

 of 14 to 100 fathoms in Lake Huron. 



RELATIVE ABUNDANCE 



The short-jawed chub has been seen in large quantities in the chub nets only 

 on its spawning grounds in 35 to 50 fathoms northward from Forty Mile Point from 

 the middle of September to the middle of October (records 2, 3, and 6). On or 

 near the same grounds it occurs in some numbers outside the spawning season 

 (records 1 and 5), but how abundant it is then is not known. 



Out of Alpena, Mich., zenithicus always has been rare or absent in the 11 lifts 

 examined, made in September and October, 1917, in the center of the lake northeast 

 or east of the city in 60 to 80 fathoms (records 7, 8, 15, 17, 24, and 25), and in the 

 five examined lifts made nearer shore in 60 to 100 fathoms on August 7, 1920, 19 

 miles NE. N. of Thunder Bay Island, June 28, 1923, 19 miles northeast of Thunder 

 Bay Island, June 30, 1923, 17 miles NE. by N. % N. of Thunder Bay Island, July 



