PROGRESS IN BIOLOGICAL INQUIRIES, 1933 359 



tion is extroinely slow, iv(|uiriii<j: many days, while a chaiijiv from 

 a lower to a hiohor salinity juM-mits rocovory within a iVw hours. 

 It is probable that adaptation to snch a low salinity is not so com- 

 j)lete that feedino; may continue as rapidly as in the higher salinity. 

 If placed in water of a salinity of about 10 per mille, feeding 

 api)ears to cease completely, though the shell may remain open 

 and shell growth continue. Specimens have been kept in this low 

 salinity for as long as two weeks without any indication of adapta- 

 tion of the feeding jnechanism, and even after being returned to 

 more favorable water recover only very slowly. It is thought that 

 these results will throw considerable ' light upon the ]M-oblem of 

 locating oyster beds in places where the oysters will fatten properly. 



INVESTIGATIONS ON AQUICULTURE 



The investigations originally undertaken in connection w'ith fish 

 cultural operations at the hatcheries have been expanded recently 

 to include field studies dealing with the many and diverse factors 

 which all'ect fish in their natural environment. This is a logical 

 expansion of the work, since it is obvious that the welfare of the 

 fish after being liberated in natural w^aters is fully as important as 

 the efficient operation of our hatcheries. It is evident that no matter 

 how successful our hatchery operations may be, the success or failure 

 of artificial propagation in terms of catchable fish is determined 

 eventually by conditions in the streams or lakes in which the fish are 

 planted. 



The experimental hatcheries at Leetown, W.Va., and Pittsford, 

 Vt., are fortunately situated to serve as headquarters for field investi- 

 gations, since each is located in a region noted for its excellent 

 fishing. Within a short distance of the Pittsford station in the 

 hjeart of the Green Mountains, there are many famous trout streams, 

 while both trout and bass waters are readily accessible from the 

 Leetown station. Extension of these field studies will be greatly 

 accelerated by an allotment from the Public Works Administration 

 for stream surve3's and stream improvement work during the sunnner 

 of 1934. 



In addition to the field work, investigations dealing with the 

 various fish-cultural problems are being conducted as in the past. 

 This work is conducted under the general direction of Dr. H. S. 

 Davis. 



POND-nSH Cm.TURE 



Owing to drastic reduction in the Bureau's appropriations, all 

 experimental work at the Fairport station was discontinued on July 

 1, 1933. when Dr. A. H. Wiebe, formerly in charge of this station, 

 severed his connection Avith tlie Bureau. Consequently the only 

 investigations during 1933 on the propagation and rearing of 

 bass were carried on the Natchitoches (La.) station. These investi- 

 gations were conducted by O. Lloyd Meehean and were a continuation 

 of those ,(^arried on at the Tishomingo (Okla.) station during the 

 summer of 1932. Tliis transfer was deemed advisable on account of 

 the better facilities for experimental work afforded by the Natchi- 

 toches station. 



69933—34 4 



