TVVKNTY-SKVKN'l'll HIKNNIAI. ItKI'OKT. 75 



froni this procedure confirmed tlie determination of aj^c and rate f)f 

 gr-owth as determined from the seak'S. A Rreat amount of woi'k had to 

 be done in devcdoping new princi])h's, for the science of fisheries consei'- 

 vation is a yonn^- one as yet and this work, as well as much of the work 

 done in the sardine investigation, will be distinct contributions to the 

 metliods employed in this science. After developing methods of finding 

 the ag(> of the fish it is an easy step to working out the comparative 

 abundance of the year classes, which will enable one to say quite posi- 

 tively which is a natural variation in abundance as distinguished from 

 actual depletion from over-fishing. 



This question of depletion is the all-important one but it is necessary 

 to observe the relation of the several year classes through several sea- 

 sons before depletion is positively proven. 



The average j^early catch of a boat fishing for albacore has decreased 

 rather steadily over a period of years. This does not necessarily mean 

 depletion but it is enough to cause anxiety. Last season there was a fall- 

 ing off in the proportion of older fish which, if it continues in subse- 

 quent seasons, is the best of evidence that depletion is occurring. The 

 ])roblem is more difficult than it appears at first sight for the methods of 

 the fisheries are undergoing change. During the past two seasons one- 

 man or "jig" boats, which catch the albacore by trolling, have increased 

 rapidly in number and the hook and line boats, which catch the albacore 

 l)y short lines on poles or by hand after they are attracted around the 

 boat by live sardine bait, complain that these 'Mig" boats scatter the 

 schools and are the cause of the reduced catches of the boats fishing with 

 the old Japanese method. These are questions which we are now confi- 

 dent are subject of solution with the methods being pursued in the 

 investigation. 



SARDINE INVESTIGATIONS. 



The sardine investigation has continued along the line of the pro- 

 gram laid down in 1920 and published in this Commission's cpiarterly 

 magazine, (Vol. 6, No. 1, pp. 10-12.) 



The objects of the investigation are stated by Mr. Thompson in an 

 article on the progress of the work, in California Fish and Game, 

 Vol. 6, No. 4, page 180, as follows : 



"The program under which the work has been done contemplates 

 (1) the discovery of depletion if it should occur; (2) the discovery of 

 any great natural fiuctuations in abundance or quality other than 

 those due to over-fishing; (3) the foretelling of these fluctuations, which 

 in other fisheries have at times caused great damage; (4) the decipher- 

 ing of those habits of the species which are of importance to the canner 

 and fisherman, such as migration, and (5) a knowledge of such facts as 

 will aid the legislator. The absolute completion of this program is 

 without doubt well removed, but contributions to it of great value 

 will be made in the verj' near future, enabling us to make at least 

 provisional answers, a thing impossible now. Among these we may list 

 the age and rate of growth, the breeding season, and the degree of inde- 

 pendence of the sardines in different regions. That the foretelling 

 of fluctuations is not visionary may be seen from the work of the 

 Norwegian fishery authorities on the herring. The other elements of 



