90 



Conservation Department 



the latter species was somewhat more advanced in development at 

 the same length. The more elongate body of the herring may be 

 found to be a constant factor when the two species are raised 

 together, subjected to the same temperature and environmental 

 conditions, but only when this is done can we put complete faith 

 in proportional differences, so great is individual variation within 

 the species. As an example may I quote Ada Hall (1925) con- 

 cerning the whitefish: ''Fry hatching at 1, 2, and 4 months after 

 spawning differ in size of body but not in size of yolk; those 

 hatching at 4 months are 4 to 6 mm. longer than those hatching 

 earlier." 



With the large number of hatchery herring promised for next 

 year we hope to sift out of the present possibilities whatever dif- 

 ferences are constant. 



Breeding. — The whitefish spawns in November and early Decem- 

 ber, as does the herring, the eggs hatching the following spring. 

 The period of incubation is dependent upon temperature. 



Famit.y Percidae 

 Pcrca flavescens Mitchill — Perch, yellow perch, ring perch 



Record of Capture. — The youngest specimens were hatched at 

 Put-in-Bay June 6, 1928. The older stage figured was captured by 

 a night haul at Shakespeare Island Lake, Lake Nipigon, Ontario. 

 The only specimens taken in Lake Erie this summer were quanti- 

 ties of young adults averaging 40.0 mm. in length, 631 in a Peter- 

 sen trawl at 8 meters off Seneca Shoals on August 8, and 212 on 

 the same day in a Petersen trawl at 20 meters in midlake, between 

 Point Abino and Sturgeon Point. 



Description. — Egg. Masses spawned at a temperature of 44° 

 to 50° F. in early spring; eggs held together in a single laj^er 

 forming hollow strings several inches wide, folded like the bellows 

 of an accordian, but reaching 3 to 7 feet in lengtli when drawn 

 out; not attached to objects on the bottom. Wide variation in size 

 of eggs (Ryder 1885) ; usually about 3.5 mm. in diameter, with 

 1.75 mm. vitellus, and large oil globule; light colored semi-trans- 

 parent, complex Q^^ membrane. Incubation period c. 27 days at 

 mean temperature of 47° F; Q^<y sac absorl)ed in c. 5 davs (Leach 

 1927). 



Fig. \l.~Perca flavescens iininedialely afler hatching, S.f) niilliiueters 



Newly hatched larva. Fig. 17. Total lengtli 5.5 mm; length to 

 vent 2.7 mm; greatest depth 0.83 mm; diameter of eye 0.36 mm; 



