40 FISH AND GAME COMMISSION 



The salmon run reaching the vicinity of the Shasta Dam after Novem- 

 ber, 1942, was forced to spawn in the river below this point. The entire 

 fall run in 1943 spawned in the river below Keswick and the spring runs 

 of 1943 and 1944 were transferred into Deer Creek and Battle Creek. 

 It is too early as yet to determine how successful the salmon maintenance 

 program below Shasta is. This will only become evident when fish that 

 have been produced by the runs blocked by Shasta Dam and have been 

 handled by the salmon maintenance program operated by the U. S. Fish 

 and Wildlife Service for the Bureau of Reclamation, return again to the 

 fishery and to the river areas in which they were produced. The first 

 effects of the salvage operation should become evident in the fall of 1946 ; 

 and the full effect of the salvage operations on the fall run will be felt 

 in 1947. 



SOUPFIN SHARK 



The decrease in the production of soupfin shark, noted in the previous 

 biennium. continued during the present. biennium. Total landings for 

 1942 and 1943 were 3,468,290 and 3,722,729 respectively. This decline 

 in landings occurred in spite of an increased fishing effort and the greater 

 efficiency of the various types of nets used. The effort required to catch 

 one shark has increased 27 times from 1942 to 1944. 



An investigation of the Vitamin A potency of the soupfin shark and 

 its relationship to the biology of the species was continued. From July 

 1, 1942, to July 1, 1944, samples of 461 livers were collected and analyzed 

 at Stanford University. During 1943 the fishery was observed ; and 

 samples of the catch were obtained along the entire coast of California. 

 Data obtained is being analyzed, and a report is being prepared for pub- 

 lication. 



The observations of the catch have indicated that in Southern Cali- 

 fornia the fisherman's catch is composed almost entirely of female soup- 

 fin. In contrast to this, male soupfin appear to be concentrated in the 

 northern waters of the State. It has been established that the vitamin 

 potency of the soupfin shark increased with size, and in the female 

 definite relationship of Vitamin A potency to the state of sexual maturity, 

 as well as the sexual development of the individual, has been found. 

 In both males and females immature individuals exhibit very low vitamin 

 potencies and their total value in terms of Vitamin A is small. On 

 attaining maturity, however, the vitamin potency increased rapidly with 

 size. This change from low potency to high potency livers begins in 

 males at a total length of about 155 centimeters, and in females at a 

 total length of about 165 centimeters. , 



OYSTERS 



After some years of trying to cultivate native oysters (Ostrea 

 lurida), in Humboldt Bay, it has been finally demonstrated that it is 

 impractical. Following the closure of the last company attempting this, 

 the commission rescinded its previous regulations closing the bay to the 

 introduction of Pacific oysters {Ostrea gigas). The bureau is planning 

 to make some experimental plants of this large Pacific oyster to deter- 

 mine the possibility of inducing it to reproduce in this area. 



Oyster cultivation was carried on successfully, especially at Morro 

 Bay; but within the last year operations of the Army Engineers in 



