GREAT LAKES COREGONIDS 



383 



lifted on September 14, 1921, after seven nights out, about 2,000 fish were taken, 

 or 81 fish per night per 1,000 feet (record 18), of which all but a few were zenithicus. 

 Zenithicus was rare in the 23^-inch nets set on September 15, 1923, between Silver 

 Island and the mainland in 14 fathoms (record 20). There was a single fish among 

 the 32 Leucichthys taken in one net (500 feet) set one night. In Thunder Bay a 

 net lifted on September 15, 1923, off Thunder Cape in 31 fathoms, after having 

 been set two nights, took 70 Leucichthys, or 70 fish per night per 1,000 feet of net, 

 of which half were zenithicus (record 21). A net lifted north of the Welcome 

 Islands on September 17, 1923, in 11 fathoms, after having been set two nights, 

 took a single zenithicus among the 16 Leucichthys (record 22). Two nets lifted 

 on September 17, 1923, south of the Welcome Islands in 23 fathoms, after having 

 been set two nights, took 121 fish, or 60 fish per night per 1,000 feet of net, of which 

 but 6 per cent were zenithicus (record 23). Two nets lifted on September 19, 

 1923, off Sawyer Bay, from 49 fathoms, two nights out, had 50 fish, or 25 fish per 

 1,000 feet of net per night, 62 per cent of which were zenithicus (record 24). On 

 September 25, 1923, two 23^-inch nets (1,000 feet of netting) set for one night in 

 Simpson Channel in 74 fathoms took only 4 fish, all of them zenithicus (record 

 26). On September 29, 1923, two nets lifted after four nights from 42 fathoms off 

 Salter Island took 25 fish, or 6 fish per night per 1,000 feet of net, of which 92 per 

 cent were zenithicus (record 27). One thousand feet of net set out of Rossport, 

 Ontario, off Bread Rock in 80 to 90 fathoms, and lifted on October 4, 1921, after 

 having been set for four nights, took about 210 fish, or 52 fish per night per 1,000 

 feet (record 25). All but 11 per cent of these were zenithicus. Two thousand 

 five hundred feet of netting lifted on June 22, 1922, 3 miles SE. 3^ E. of the Quebec 

 Harbor Light on Michipicoten Island in 80 fathoms, three nights out, took 75 fish, 

 or 10 fish per night per 1,000 feet (record 30), of which 60, or 79 per cent, were 

 zenithicus. One thousand eight hundred feet of netting lifted off Alona Bay on 

 the east shore of the lake on June 26, 1922, in 60 fathoms, after having been set 

 for five nights, took about 200 fish, or 22 fish per night per 1,000 feet (record 32), 

 of which 87 per cent were zenithicus. The fish taken in the 4^-inch nets in 

 Michigan waters, out of Grand Marais (record 2), Marquette (records 3 and 6), 

 and Ontonagon (record 10); in Wisconsin waters off South Twin Island (records 

 14, 15, and 16); in Minnesota waters off Grand Marais (record 19); and in Ontario 

 waters off Port Coldwell (record 28), Michipicoten Island (record 29), and Copper- 

 mine Point (records 31 and 32), were only casual inclusions and can show little 

 concerning the abundance of these fish. 



These data indicate that zenithicus occurs more or less abundantly at depths of 

 11 to 100 fathoms, but they do not mark the zone of maximum abundance for the 

 species because the various observations have been made at different seasons and at 

 different places and make no allowance for seasonal migrations nor for differences of 

 habit induced by different physical conditions. It is clear, however, that the gangs 

 set exclusively in depths of 60 to 100 fathoms average only 17 zenithicus per night per 

 1,000 feet (records 5, 25, 26, 30, and 32), while those set wholly or in part at depths of 

 15 to 45 fathoms average 41 zenithicus (records 1,4, 11, 12, 13, 18, 21, 23, 24, and 27). 

 In shallower water the species has been found rare. The data indicate further that 



