350 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



that instinct which impels the adult fish to return, for the purpose of 

 spaw ning, to the place where they were liberated in infancy. In a state 

 of nature the minnows arc released only from spawning beds; and the 

 area of grounds adapted to spawning purposes is quite limited. Bar 

 we are permitted to introduce the young at will, and thus establish 

 new initiatory routes on which they may be intercepted by the devices 

 of man. 



It is not at all probable that the parent fish will deposit their eggs in 

 unsuitable places, though it is where they were first set fiee and they 

 have returned for that purpose. It is far more likely that they will cou 

 tinue on the move tin til appropriate grounds are found. Some of the 

 best whitenshing grounds of Lake Erie are neither spawning nor feed- 

 ing grounds. We refer more particularly to the shore grounds between 

 Sandusky, Ohio, and Monroe, Mich. Thousands of whitefish are taken 

 here every fall from the runs setting toward the spawning beds of the 

 Detroit River. Comparatively few ripe fish, however, are taken below 

 Monroe; at Monroe the percentage of ripe fish is a little better; but The 

 Detroit River is reached before the spawning has become general. The 

 best spawning grounds of the lake are the island shoals between San- 

 dusky and the Canada shore; and the runs thereto set in, apparently, 

 direct from the deep waters lying eastward, and from the Canada shore. 



The statement in reference to the abundance of saugers in the locality 

 referred to by Dr. Sterling is substantially true; but the conclusion that 

 in consequence "no other fish can exist" is manifestly at fault. Some 

 other cause must be given for the scarcity of whitefish in that locality. 

 Thousands of saugers are taken every fall from some of the best white 

 fishing grounds of the lake. From the spawning shoals around the 

 Bass islands they are brought in with every lift during the spawning 

 season of the whitefish, besides herring to the proportion of fifty herring 

 to one whitefish. Again, in the spring, not far from the time the young 

 whitefish are rising from the spawning beds, the saugers are even 

 more numerous, to say nothing of the hundreds of basses and pikes that 

 comprise the best part of the spring catch. It is safe to say that preda- 

 tory fishes abound iu greater numbers near these spawning beds, both 

 at spawning time and soon after the fry are set free, if not continuously, 

 than where the Cleveland plant was made. And yet the young white- 

 fish are always set lice, in a state of nature, in the very midst of these 

 apparent dangers without diminution of the species. 



It might be argued that the great fecundity oi the specie-* would more 

 than offset these manifold dangers; but this, in turn, is more than offset 

 by the fact that by far the greatest losses of all occur during the em- 

 bryonic stage of development. Conferva, against which artificial ma- 

 nipulation alone is able to cope, is the fell destroyer — the octopus wit bin 

 whose grasp countless thousands of embryos annually perish. Only 

 the comparatively few that are completely isolated can escape destruc- 



