The Common Whitefish 



small scale in September, during which month a few individuals 

 are sometimes captured in the poundnets on the platform. It 

 does not become pronounced, however, until in October and, in- 

 cluding the up and down runs, continues through November 

 and more or less into December, although very few fish are 

 taken during the last mentioned month; that is to say the 

 poundnet catch seems to be obtained chiefly, if not almost en- 

 tirely, from the up run, making it possible that the bulk of the 

 down run keeps farther offshore. 



The fall run strikes in along both shores the same as the 

 spring, but at the western end of the lake the fish now become 

 widely distributed over the platform, and a large number pass 

 through the Detroit River into Lake St. Clair. There is consider- 

 able difference in the dates of the appearance of the fish at 

 different places, especially on the platform, but this diversity is of 

 only local significance. It is not improbable that during the 

 western movement a certain proportion of the fish also proceed 

 through the deeper waters until they reach the platform, but 

 nothing positive has been learned regarding this matter, as the 

 schools are never followed by the gillnetters as in the case of 

 the herring. 



After the whitefish reach their spawning grounds on the 

 western platform, they give rise to an extensive local gillnet 

 fishery of very limited duration. During their passage up the 

 Detroit River, mainly in the latter part of October and the early 

 part of November, they are caught by means of seines, and in 

 Lake St. Clair a few are taken in the pound nets. 



It is interesting to note that during the spawning period a 

 large body of fish still remains in the deeper water, where the 

 gillnetters continue to take them, though in smaller quantities 

 than in the summer and in the early fall. 



The entire distribution of the spawning grounds of the white- 

 fish in Lake Erie is not known. During the spawning season 

 a part of the fish remain in their normal deep-water habitat, but 

 it is not probable that they spawn there. The regular fall move- 

 ment carries a very large body to the western platform, where 

 many well-defined spawning grounds occur. These are chiefly 

 rocky reefs and shoals, characterized in part by the water-worn 

 surfaces of the common limestone of the region, the so-called 

 honeycombed rock. Hard gravelly and sandy bottoms in some 



125 



