128 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



that the number caught in 1890 was less than the number caught in 1880. This may 

 have been due to a diminution in the number of fish, but it may also have been due 

 to storms during the fishing season of 1890. Statistics, to be conclusive, should enable 

 us to compare the average yield for the ten years 1870 to 1880 with the average yield 

 for the years 1880 to 1890. 



No such continuous series of statistics is in existence for the United States, so 

 that the assertions concerning a diminishing yield of whitefish rest either on a com- 

 parison of the statistics of isolated years or on the statements of fishermen concern- 

 ing certain localities. 



If we inquire into the facts concerning the sufficiency of the present methods of 

 artificial propagation we find that, so far as concerns the whitefish, there is no ques- 

 tion as to the success of the earlier stages of the process. Several hundred million 

 ova are taken annually and placed in the hatcheries, and of these usually from 80 to 

 90 per cent are hatched and placed in the waters of the Great Lakes, 165,000,000 in 

 Lake Erie alone in 1888.* 



This is very nearly all that is known about these young whitefish. About tbeir 

 food habits we know only thatf in captivity they eat certain species of crustacea.t 

 Whether in their natural habitat they eat other animals in addition to these Crustacea 

 or in preference to them we do not know. It is uncertain at what age they begin to 

 take food, or how much they require. We do not know their natural enemies. We do 

 not know whether they thrive best in running water or in standing water; in shallow 

 water or in deep water ; whether at the surface or near the bottom. What changes of 

 habitat or of food habits the fish undergo as they grow older is a still deeper mystery. 



Our problem is to place young whitefish in the Great Lakes under such conditions 

 that as large a number as possible of them shall grow into adult fish. It is clear that 

 of one of the elements in this problem, namely, the whitefish, we know but little. 



What, then, do we know of the other element of the problem, the Great Lakes 

 themselves? Individual naturalists have made efforts from time to time to study one 

 or another of the groups of animals living in the lakes. These efforts have been 

 always circumscribed by the facilities at hand, by the time that could be devoted to 

 the subject, by the small area examined, or by the small number of animals taken 

 into account. Although much excellent work has resulted from these efforts, it 

 remains true that there has been thus far no attempt to secure an accurate knowledge 

 of all the conditions existing in any one locality, and no attempt to study exhaust- 

 ively a single group of the animals and plants of the lakes. We are still at the 

 beginning, so far as concerns a knowledge of life conditions in these lakes — the con- 

 ditions with which we surround our young whitefish. If we could assume that the 

 conditions are uniform over the whole area of the Great Lakes, then, since the youug 

 whitefish are native to these lakes, it might be a safe conclusion that they will find 

 the conditions in one locality as well for them as in another. But there are no facts 

 which support the view that the conditions are uniform over the lakes. 



We are thus in the position of bringing together under unknown conditions two 

 things, both of unknown character, and we expect as a result to get a third thing, 



 This appears by adding the number of fry planted in 1888 by the U. S. Commission and by the 

 commissions of Canada, Michigan, New York, Ohio, and Pennsylvania, as shown in the reports of those 

 commissions. f 



t Forbes, S. A., The First Food of the Common Whitefish. Bulletin No. 6, Illinois State Labor- 

 atory of Natural History, May, 1882. 







