130 FISH AND GAME COMMISSION 



This work is dependent on the detailed information recorded on the 

 fisli buj'ers' receipt book tickets. The perfectin*? of our statistical 

 system and the orderly filing of the receipt tickets were necessary 

 preliminaries which have now been accomplished to such an extent 

 that we are able to go forward with the studies for determining deple- 

 tion by means of boat catch analysis. Such determinations have 

 recently been made in four important California fisheries and similar 

 studies will be made in other fisheries as rapidly as possible. The 

 catches of striped bass, white sea bass, bluefin tuna and California hali- 

 but have been analyzed, and in two of the four fisheries the supply was 

 found to be diminishing with alarming rapidity. In the case of bluefin 

 tuna the available supply seems in no immediate danger. The striped 

 bass fishery of the San Francisco Bay and Sacramento River region 

 was found to be in a healthy condition due chiefly to increasingly 

 stringent protective legislation during past years. 



SARDINES 



The major problem of our research program is to gain an understand- 

 ing O'f the available sardine supply and to learn the effects of our 

 present utilization of this most important species. We early found 

 that the study of the sardine supply off the California coast oft'ered 

 unforeseen difficulties in that the success of spawning was extremely 

 variable from year to year, resulting in dominant and comparatively 

 lacking age classes. We found extreme seasonal variation in the sizes 

 appearing in the commercial catch and discovered baffling spawning or 

 feeding movements in and out of the fishing areas. The determination 

 of age, rate of growth and size at maturity were found to be unexpect- 

 edly difficult because of the complex nature of this fishery. 



During the last bienniura we have made gratifying progress toward 

 the solution of the more important problems connected with this diffi- 

 cult study. Our work at San Diego has furnished an understanding 

 of the rate of growth and age of the .small sardines taken at that port. 

 Through cooperation with Stanford University in the hydrographic 

 survey of Monterey Bay, we have learned much of the spawning 

 localities, eggs, and larval stages of the sardine. Our sampling of the 

 commercial catch at San Pedro and jMonterey has given us a better 

 understanding of the rate of growth of the larger fish, the appearance 

 and recurrence of dominant size classes in the catch and has suggested 

 criteria that may be used in determining the presence or absence of 

 over-fishing. Studies of egg samples are giving us the determination 

 of the spawning season, the size of fish at sexual maturity, the propor- 

 tion of the fish population maturing at any given size and the normal 

 number of spawnings to be expected from individuals. 



Detailed examination of the variations in the yield from various 

 fishing localities has given us significant though not conclusive evidence 

 of the strain upon the fish population suffered under present utiliza- 

 tion of our supply. Close watch has been kept upon changes in the 

 amount and character of the fishing effort expended and the results 

 have been published. Field work has been extended to include obser- 

 vations at monthly intervals of the sizes of fish and state of sexual 

 maturity of sardines at Pittsburg. 



