20 KEPORT or THE COMMISSIONER OF FISHERIES. 



SHELLFISH INVESTIGATIONS, 



Oysters. — The problems of the oyster industry in some sections 

 are critical and have received the fullest possible measure of atten- 

 tion. The problem of first importance is the failure of set during a 

 period of years in Long Island Sound, and this has been attacked 

 by methods of both biology and chemistry (in cooperation with the 

 Bureau of Chemistry.) A foundation of facts is steadil}^ being con- 

 structed, and some tentative conclusions as to the causes of trouble 

 and the methods of alleviation are now possible. No claim can, 

 however, be laid to a complete solution of the problem until further 

 observations and experiments have been made. The inquiries have 

 centered principally about Milforcl, Conn., and Sayville, N. Y. 



It seems fairly clear that one of the disturbing factors, and pos- 

 sibly the chief cause of the failure of set, is the extensive pollution of 

 inshore waters by sewage or industrial wastes, and proper attention 

 is therefore being focused upon this aspect of the question. 



Oyster studies have also been made in the Chesapeake Bay and in 

 some waters of the State of Virginia. In the vicinity of Norfolk 

 attention has been given to the damages to oysters resulting from the 

 unlawful discharge of oil upon the waters of Hampton Roads. In 

 the York River, Va., the investigation of conditions affecting un- 

 favorably the growth of oysters has been brought to a close. 



Fresh-water mussels. — In the propagation of fresh-water mussels 

 the number of glochidia infected upon fish and liberated in the 

 public waters was conspicuously greater than in the preceding year, 

 and the unit cost was correspondingly lower. The results of arti- 

 ficial propagation are detailed elsewhere. In the experiments di- 

 rected at the rearing of young mussels until they have attained a 

 size (say half an inch in length) permitting of their being handled 

 with convenience and planted deliberately upon suitable bottoms, 

 notable results have been secured during the year. Before the past 

 year a measurable degree of success had been . attained with one 

 species of mussel (the Lake Pepin mucket), but during the summer 

 of 1919 two additional species (yellow sand-shell and river mucket) 

 were reared in considerable quantities in small troughs. 



At a conference in La Crosse, Wis., in January, 1920, participated 

 in by representatives of the States of Wisconsin and Minnesota and 

 by other interested persons as well as by assistants of the Bureau, 

 consideration was given to the protection of mussel resources, and, 

 acting upon authority provided by recent concurrent legislation in 

 several States, it was determined to close against commercial shell- 

 ing for a period of five years certain sections of the Mississippi River 

 bordering the two States represented in the conference. The pur- 

 pose is to allow opportunity for natural recuperation of the beds and 

 to create favorable conditions for the artificial propagation of mus- 

 sels. The proposed action, when taken, will represent the culmina- 

 tion of several years of earnest effort by various persons and agencies, 

 in which the Bureau of Fisheries has played a leading part, to bring 

 about the effective protection of the valuable mussel resources of the 

 Mississippi Basin. Up to the present time, only four States w'lich 

 control the principal mussel-producing portions of the Mississippi 

 River have enacted appropriate legislation. It is greatly to be de- 

 sired that other States having jurisdiction over important shell-pro- 



