VIII REPORT OF THE COMMISSIONER OF FISHERIES 



FISHES OF INLAND WATERS 



The wliitcfisli and cisco fisheries represent the most iuipoitant 

 fislieries of the Great Lakes. In 1922 the catch exceeded 40,000,000 

 j)ounds, or 40 per cent of the entire catch, and more than $2,000,000, 

 or 31 per cent, in value. These fislieries have shown marked deple- 

 tion in recent years. It is therefore highly important that adequate 

 information he provided as a basis for proper conservation measures. 



Impoitant advances have been made in the investioation of the 

 wliitefislies of the Great Lakes, and a report dealing with these fish- 

 eries, Avliich are supported largely by the whitefishes and related 

 species, has been sul)mitted for publication. Detailed studies of the 

 systematic relationships and the natural history of the whitefishes 

 and ciscces are being conducted. One fact of importance that has 

 been disclosed in this investigation is that the herring of Saginaw 

 Bay suddenly increased their rate of growth in 1919, and that this 

 increased growth has been maintained since that date. This sudden 

 acceleration in growth is apparently correlated with improvements 

 in the environmental conditions in SaginaAv Bay due to decreased 

 pollution. 



Investigations of the natural food of certain fresh-water fishes 

 and of their ecological relationships have been carried on with the 

 efficient cooperation of the faculty of the department of zoology of 

 the University of Wisconsin. Other important studies relating to 

 the nutrition and physiology of fishes and other cold-blooded aquatic 

 animals have been carried on. Work of this character has a direct 

 bearing on fish-cultural methods. 



OYSTERS 



The oyster industry of the Atlantic coast, with an annual yield of 

 about 20,000,000 bushels, is one of the most valuable of our aquatic 

 resources. At one time our most valuable fishery, it has sutfei-ed 

 serious depletion in recent years. Production has been reduced by 

 as much as 50 per cent in some important areas. During tlie past 

 fiscal year investigations have been conducted into the causes for this 

 depletion and means whereby it might be remedied. 



A hydrographic and biological survey of Long Island Sound, 

 where the situation as regards the oyster industry is especially acute, 

 has been completed, and a report *is nearly ready for publication. 

 This survey was undertaken in order to supply data regarding con- 

 ditions having an immediate bearing on the problems of oyster 

 culture. Tlie results indicate that the difficulties of oyster culture in 

 Long Island Sound are due primarily to (1) the pollution of the 

 best spawning beds by sewage and trade wastes, (2) the overfishing 

 of such spawning beds as remain unpolluted, and (3) the exposure 

 of these unpolluted spawning beds to the attacks of starfish and 

 oyster drills. 



"^The oyster studies that have been in progress for some years in 

 Long Island Sound and in Great South Bay were continued. In 

 (Trej7t South Bay attention was directed to the discovery of the 

 cause of the heavy mortality among young oysters, and to the de- 

 velopment of additional knowledge of the early life history of the 



