REPORT OF THE COMMISSIONER OF FISHERIES. 19 



OYSTER INVESTIGATIONS. 



Oyster investigations in Long Island Sound and Great South Bay 

 "were continued during the year, the field work lasting from early 

 in June until September 20. 



The special purpose of the work in Great South Bay is to discover 

 the cause of the great mortality which frequently occurs after an 

 abundant ''set'* has apparently established the basis for a good 

 crop. The jjresumption has been established that this is due to con- 

 ditions i^eculiar to the bottom or the stratum of water near the bot- 

 tom. Well-grown oysters of the set of 1921 were found in compact 

 groups in various situations a few feet above the bottom, while all 

 those that had set so abundantly on or near the bottom had died 

 shortly after becoming attached. The work planned for the summer 

 was the testing of various types of cultcli that would permit a set 

 above the danger zone, but this purpose was defeated by the exceed- 

 ingly poor set of 1922, possibly due to unstable water conditions. 



The investigations in Cunueclicut revealed that a much better 

 than ordinary set followed a reasonably early spawning in harbor 

 and inshore waters, lending some confirmation to the j^revious indi- 

 cations that failures of recent years have been due to the depletion 

 of the inshore beds from overfishing and the results of pollutions. 

 Oyster larvae were found in Housatonic River, recently devoid of 

 oysters, where some had been planted in the spring. 



In cooperation with the Bureau of Chemistry a study was made of 

 conditions in Housatonic River and New Haven Harbor in respect 

 to trade pollutions from heavy metals, oxygen content, and alka- 

 linity. One of the difficulties encountered in all of these investiga- 

 tions has been the lack of precise information regarding the pris- 

 tine and present hydrographic and planktonic conditions. To fur- 

 nish such data of the existing state of the Avaters, the Fish Haivk, 

 under the direction of the naturalist of the Albatross, was detailed 

 to make a survey of conditions that might bear on the mortality 

 obtaining among the oyster fry and the spat after a brief period 

 of survival. The field work was practically complete at the close 

 of the fiscal year, with the exception of a few weeks' special study 

 of inshore polluted areas. 



IN\TESTIGATIONS RELATING TO FISH CULTURE. 



The biological station at Fairport, Iowa, has continued its experi- 

 ments in the culture of various of the important commercial fishes 

 of the Mississippi Valley. The hatching and rearing of buffalo 

 fish in ponds as an adjunct to the farm-food supply appears feasi- 

 ble, but it is doubtful if the species can be so produced on a com- 

 mercial scale, owing to the large pond area required for attainment 

 of maximum growth in large numbers. 



The results of experiments with the channel cat have been suffi- 

 ciently promising to warrant setting aside several ponds for the 

 work, and at the close of the year the indications were that there 

 would be justification for undertaking the work on a basis of prac- 

 tical magnitude next season. 



The spawning habits of the paddlefish, a disappearing species par- 

 ticularly valuable for the production of caviar, are entirely un- 



