XVI REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



continued and are aifording interesting information which will be of 

 value in the propagation of these fishes; and investigations in Lake 

 Superior, which were begun in April, 1897, having for their object the 

 determining of the food supply of the fishes of that lake, will, when fin- 

 ished, yield information of value in the planting of fish fry. Large 

 collections of minute animal life have been made from Lake Superior, 

 the study of which has not as yet been completed. 



On account of the survey of the fur-seal rookeries made by the 

 United States Coast and Geodetic Survey in the summer of 1897, and the 

 second visit to the seal islands of the special commissioners who were 

 appointed the previous year to report on the conditions of seal life, it 

 was not deemed necessary by the Secretary of the Treasury for this 

 Commission to send an agent to the islands to make the usual investiga- 

 tions. Arrangements were made through the courtesy of the special 

 commissioners to obtain for this ofQce photographs of the rookeries 

 and the requisite data to continue its series of maps showing the 

 changes in condition of the fur-seal rookeries from year to year. 



The subject of the i^ollution of rivers and streams by mill and factory 

 refuse, and the discharge of sewage from the towns and cities on their 

 banks, is receiving much attention from those interested both in main- 

 taining proper sanitary conditions and in the preservation of fish life. 

 A memorial prepared by the Game and Fish Protective Association of 

 the District of Columbia, urging the importance of action in this matter, 

 was presented to Congress March 17, 1898, and published as Senate 

 Document 194, Fifty-fifth Congress, second session. At the request of 

 the chairman of its committee, a letter containing extracts from publi- 

 cations of this Commission, showing the evil effects produced upon fish 

 life by the contamination of streams, was submitted by this office to 

 the association for incorporation in the memorial. As stated in this 

 letter, "the data are sufficient to clearly establish the point that river 

 pollution is both directly and indirectly most injurious to fish and 

 the fisheries by destroying fish and fish eggs, by driving fish away, by 

 interfering with the fishing apparatus, and by killing or impairing the 

 supply of minute animals and plants which are the basis of fish life." 

 Eemedial legislation is greatly to be desired in many localities. 



During the summer of 1897 the Woods Hole laboratory was occu- 

 pied by a small number of investigators, the attendance having been 

 restricted to representatives of those institutions which had furnished 

 financial aid in the establishment of the laboratory. The continued 

 scarcity of mackerel rendered it important to continue the study of 

 these fislies with a view to the satisfactory solution of the problem of 

 their artificial propagation on a large scale, and among the inquiries 

 carried on at Woods Hole was an investigation by Dr. J. Percy Moore 

 relative to the embryology, natural history, and artificial propagation 

 of the mackerel. The report of Dr. Moore is published as an appendix 

 to this report (pages 1-22). 



In the spring of 1898 steps were taken to increase the opportunities 

 for scientific t^tudy at Woods Hole and to keep the laboratory open 



