THIRTY-SEVENTH BIENNIAL REPORT 49 



Tagging of sardines was continued. Recovered tags have indicated 

 that the sardine populations intermingle freely along the coast from 

 California to British Columbia. These returns have also given a measure 

 of the rate the sardines are caught by the fishery. Although the total 

 catch has remained stable at about 550,000 tons since 1935, investigation 

 of the catch indicates that there has been a decrease in the returns 

 obtained by each boat. A decrease has also been noted in the size of fish 

 composing the commercial catch. For example, in 1936-37 the average 

 number of sardines in a ton was 6,056, while in 1941-42 it was 9,145, 

 representing approximately a 50 per cent increase. Thus it took 50 

 per cent more fish to make up a ton of fish in 1941-42 than it did in 

 1936-37. 



Although there is no reason to be concerned over the possibility of 

 the extermination of the sardine by the fishermen, there is a possibility 

 that if the fisherj^ is carried on too intensively, the population will decline 

 to the point where the success of a fishing season will depend upon the 

 chance occurrence of an abundant year-class. It is expected that investi- 

 gations now underway will, when completed, assist in the determination 

 of the point at which the sardine fishery should be stabilized. Progress so 

 far has served to emphasize the importance of a more thorough investi- 

 gation of the rate of recruitment, since preliminary results obtained so 

 far have indicated that the survival of young fish may not yet have been 

 adversely affected by the fishery. Further investigation of this problem 

 is now impossible due to the war. However, as soon as opportunity offers, 

 the variation in numbers of young sardines that are produced each year 

 must be studied intensively with the associated factors that cause such 

 variation. When regulation is finally undertaken, it must be in the form 

 of control of the total catch. The total catch is not controlled by present 

 restrictions, which curtail only the number of tons of sardines taken for 

 straight reduction and are insufficient for proper management. 



TUNA 



During 1940 a total of 199,556,603 pounds of the five species of tuna 

 was landed in California ports, with a resulting pack of 3,799,912 cases. 

 The 1941 tuna season was not as successful as that of the previous year, 

 and only 124,729,913 pounds were taken and 2,400,862 cases packed. 

 The decrease in the landings of 1941 was due to factors that are at present 

 unknown ; and the investigations by this bureau have not been sufficiently 

 widespread to ascertain the causes. However, there is no reason at present 

 to feel that this decrease is due to overfishing. 



Immediately after December 7, 1941, tuna boats were prohibited from 

 operating farther south than 10° N. latitude, which eliminated the very 

 productive grounds in the vicinity of the Galapagos Islands and along 

 the Central American coast. A number of the large tuna boats had 

 already been acquired by the Navy, and before the end of the biennium 

 most of the boats above 90 feet in length had been taken. 



The investigation of the tuna fishery so far has been confined to an 

 examination of the different species upon which the fishery is based. 

 The studies therefore have been largely systematic in nature. Additional 

 work has also been started to determine if the fishery is exploiting more 

 than one population of each of the species concerned. Assistance has 



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