GREAT LAKES COREGONIDS 



405 



in 20 to 35 fathoms, by D. H. Smith & Sons (record 13), was found on examination to 

 be chiefly reighardi. 



In the l^-inch bait nets, lifts made from 28 to 40 fathoms on September 28, 

 1920, 5 miles SE. by E. of Sheboygan, Wis.; on June 23, 1920, off Northport Point; 

 and on July 18, 1923, in West Traverse Bay, from 20 to 30 per cent of the small 

 fish gilled were reighardi (records 9, 33, and 35). They were rare in similar lifts 

 made off Port Washington, Wis., on September 25, 1920, and on March 2, 1921, 

 off Michigan City, Ind., in 26 to 30 fathoms (records 12 and 23). The special 

 13^-inch nets set in Platte Bay on the Michigan shore, in West Traverse Bay, and 

 off the South Manitou Island in July, 1923, in 4 to 25 fathoms (see Table 68) took 

 few or no specimens of this species (records 31 and 36). 



It appears from these data that for unknown reasons few reighardi were taken 

 in the chub nets during the summer and fall of 1920. On several occasions in later 

 years it has been found common in the chub hauls. The records of maximum abun- 

 dance are from lifts made between 30 and 60 fathoms. Inasmuch as juvenile speci- 

 mens have been taken commonly in the bait nets, and occasional specimens have 

 been found ensnarled in the trout nets, both of which are set regularly at less than 

 40 fathoms, it seems probable that the species prefers the shallower waters and that, 

 therefore, the above-mentioned limits indicate more or less closely the zone of maxi- 

 mum density for the species. 



BREEDING HABITS 



The time and places of spawning are not definitely known. There are, however, 

 data bearing on both, which are worthy of consideration. Of the fish examined at 

 Michigan City, Ind., on March 2, 1921, at Grand Haven, Mich., on March 20, 

 1919, and Milwaukee, Wis., on March 24, 1919, most of the males showed pearl 

 organs and emitted milt on pressure and the females exhibited ova nearly fully 

 developed. The specimens received from Michigan City on April 1, 1921, had sex 

 organs in about the same stage of development, except that 2 of the 26 females were 

 spent. Of 39 females received from Charlevoix, Mich., taken on May 3, 1924, 7 

 were spent, 1 was spawning, and most of the rest had eggs nearly ripe. Males 

 received from Port Washington, Wis., on May 26, 1921, had no pearls (these structures 

 are very frail and are removed easily by friction), but milt was exuded, and the 

 females had ova nearly mature. It should be pointed out, in this connection, that 

 if the nets were not actually set on the spawning grounds only spent or unripe fish 

 would be taken, and the data just reviewed do not indicate more than that the speci- 

 mens were taken at a period not remote from the spawning season. At Northport, 

 Mich., on June 22, 1920, and at Charlevoix on June 29, 1920, females were collected 

 that were spent or still had some eggs in the body cavity. Female specimens taken 

 thereafter exhibited ovaries in which the eggs of a new season were appearing, but 

 an occasional pearled male or a female with retained ripe eggs was taken at Wash- 

 ington Harbor, Wis., on August 18, 1920 ; at Sturgeon Bay, Wis., on August 23, 1920; at 

 Algoma, Wis., on August 24, 1920; at Michigan City, Ind., on September 3, 1920; and 

 at Port Washington, Wis., on September 25, 1920. Whether these abnormal individ- 

 uals matured their sex products with the rest and were not relieved of them normally 

 or whether the germ cells ripened at abnormal periods is uncertain. The examina- 

 tion of the sexual condition of collected specimens thus indicates that spawning must 

 occur sometime between the last of March or first of April and the last of June. 



