then read for age, v;ithout knowledge of the size of fish, and v/ith fre- 

 quent changes in magnification to avoid being influenced by the size 

 of the scales. It was found that 20 percent of the scales were illegible, 

 and 5I4 percent of the read'ings questionable. In a subsequent examina- 

 tion, with reference to the size of the fish, 61 percent of the readings 

 were questionable, and 25 percent of the scales illegible. A comparison' 

 of the two readings indicated that, what vdth disagreements and illegi- 

 bility, only about 25 percent of the total age determinations were com- 

 pletely acceptable, \fhen the length of the fish at each age was calcu- 

 lated from the scales by Lea's method (Lea, 1913), Thompson found such 

 discrepancies between the actual lengths of fish at the several estimated 

 ages and the lengths at those ages as calculated from older specimens 

 as further to discredit the dependability of reading pilchard scales. 

 He says, then (Thompson, 1925, p. 53), "So important is the analysis 

 by age regarded at present that it is with the greatest regret that it 

 is temporarily omitted. Vfe — the dii-ector and the successive assistants — 

 have vainly attempted to read the age marks on the sca.les and otoliths. 

 This does not mean that the attempt to utilize thera will be abandoned. . 

 ... we may be able to develop a method of accurately reading the scales 

 according to the age their lengths should indicate. This attempt is al- 

 ready in progress." And, on p. 57, 'HVith this simple presentation of 

 results the use of scale readings is concluded for the time being." 



No further studies were carried to completion following Dr. Thompson's 

 preliminary report, however, and no other publications have appeared 

 to date on this subject. Nevertheless, the possibility of determining 

 the age of pilchards from scgles and otoliths was not closed, and the 

 belief was expressed from time to time by those studying the species 

 that the subject must be further studied. 



Accordingly, by agreement vath the California Division of Fish and 

 Game, the staff of the United States Fish and v;ildlife Service engaged 

 on pilchard research took as one phase of its program a study of the 

 problem.!/ This paper, the first report on the resiJ.ts of that study, 

 inquires critically into the utilization of scales and otoliths for de- 

 termining ages of pre-adult sizes of pilchards; that is, those ranging 

 from the smallest taken by bait fishermen up to those around 185 wra. 

 in length, which is approximately the size at which 50 percent of the 

 females become mature (Clark, 193U). In addition, somewhat less critical 

 results are given for fish up to around 220 mm., at which size 100 per- 

 cent of the females are mature. 



i'This study has been made possible only by the cooperation of 

 members of the fis.hing industry, who aided in our collection of material. 

 The authors are grateful to the following fishermen or dealers, who 

 took an active interest in securing samples of the bait fisheries: 

 Messrs. J. L. Sullivan, Eugene Sullivan, Dominic San Phillipo, and 

 Leonard Schipper at San Dlegoj Joe Dixon and George I^son at Newport 

 Beach} S. Carmen and Frank Pugleise at San Pedro; lH. Martinelli at 

 San Francisco} and Thomas A. I^lartin, Jr., at Seattle, Washington. The 



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