TROGRESS IN BIOLOGICAL INQUIRIES, 193 3 367 



favorable coiulition.s for oxi)erinuMital ^vork. One stroam, Scott 

 Creek, has been closed for years by an inii)assable dam near its 

 mouth Avhere all aseendinj^ steelhead are tra])ped and spawned. 

 During the past summer a dam was constructed on Waddell Creek 

 whicli will automatically trap all adult fish mifi:ratin<j: upstream 

 and will also capture a portion of the downstream mijjjrants. In 

 this stream the adult fish, after bein<i^ measured and tagjj^ed, will be 

 allowed to pr(x:eed upstream and spawn naturally. It is hoped in 

 this way to obtain, anion*:: other thin<;s, accurate', data on the com- 

 parative eUiciency of natural and artificial ])roi)a<i;ation. 



Duriufi; the period January to May 1938, 82 adult steelhead trout 

 of the G14 ta<r<ied the previous year returned to the station on Scott 

 Creek. These fish had been tag<j:ed on the gill cover with a no. S 

 strap tasr. Of these 82 fish Gl percent returned carrying the tag, 

 and the balance were recognized by the hole in the abraded area 

 where the lost tag had been attached. During the same period 368 

 fish were tagged after spawning, including the fish previously 

 tagged. On these fish the celluloid disk tag attached by a nickel 

 wire just ])elow the base of the adipose fin was used. In addition 

 to the work on the adults, 11,000 yearling fish were marked and 

 planted in the lagoon. 



Some field work was done on the Klamath River during the sum- 

 mer, and arrangements were made to hold fish in the Fall Creek 

 hatchery for marking experiments during the coming spring. It is 

 planned to expand the work on the Klamath considerably during the 

 coming j'ear. 



FISH DISEASES 



Studies of the bass tapeworm at the Fairport (Iowa) station, 

 started in the summer of 1932 by Dr. Frederic F. Fish, were continued 

 during the spring of 1933. These investigations show that this tape- 

 worm has not caused serious injury to the bass at Fairport. 



A detailed study of the causes underlying the heavy loss of bass 

 fry in the nursery ponds indicated that protozoan parasites, particu* 

 larlj^ Cyclochaetea, are largely instrumental in causing such losses, 

 and it was concluded that as a routine practice all fish should be 

 dipped in a salt solution before they are placed in ponds. It was also 

 found that smaller quantities of fry should be handled during the 

 process of counting and weighing than has been the practice in the 

 past. 



Later in the season Dr. Fish made an investigation of a trout 

 disease at the Cortland (N.Y.) station which caused a heavy loss 

 among the fingerling trout. The disease is characterized by exter- 

 nal lesions not unlike those of furunculosis and consequently has 

 apparently been confused with it. However, detailed studies of the 

 pathology of the disease show very clearly that it is quite distinct 

 from furunculosis. Like furunculosis, it is highly pathogenic to many 

 species of trout and has apparently caused serious losses at several 

 hatcheries in New York State. The disease is evidently of bacterial 

 origin, and several species of these organisms were isolated from the 

 tissues. Although one of the organisms isolated from diseased fish 

 is pathogenic to trout, it has not yet been demonstrated that it is the 

 primary cause of the disease. 



