Collection of I^terlal 



So as to determine the characteristics of an age mark and to observe 

 the time Vichen it forms, scales of young fish of known age, tl^at is to 

 say, young of the year, were studied during an l8-raonth period beginning 

 with March, 1938. l.fe.terial v^ras obtained by sampling bait fisheries in 

 southern California, which is the center of this industry, and which is 

 probably the region of raaxijTial spavming (Scofield, 193U). '.'eekly samples 

 at San Diego, Newport Beach, and San Pedro vrere taken wherever they were 

 available, i.e., in the fresh fish markets, from fishermen with whom 

 special arrangements to save young pilchards had been made, from can- 

 neries, from bait receivers, or from the live-bait tanks of commercial 

 pleasure boats v Enough fish v;ere taken to total, for all localities, 

 about 1500 specimens each week, and to average about !?00 from each lo- 

 cality. This vfork was carried on regularly from Ivlarch, 1938, to May, 

 1939. Lleanwhile, to have a representation from other parts of the pil- 

 chard range, fish were obtained elsev/here by various means. 



Beginning November, 1938, and extending thi^ough October, 1939, 

 weekly samples vrere taken of the bait fisheries at San Francisco and 

 Monterey. In addition, several samples from Mexico were supplied by 

 tuna boat captains j and in July, 1938, Captain C. W. Thomas of the coast- 

 giiard cutter, Hermes , invited the senior author to accompany the Hermes 

 on a voyage to Magdalena Bay, Lovrer California, Virhere, for one week, 

 daily samples were taken, totaling altogether 1500 specimens. 



Kerckhoff Marine Laboratory of the California Institute of Technology 

 provided laboratory facilities for the southern California station. All 

 the staff members of the United States Fish and > midlife Service (formerly 

 Burea.u of Fisheries) engaged on pilchard research have contributed some- 

 thing toward the progress of this study. Mr. Robert Luckhardt was en- 

 gaged in sampling the bait fisheries in southern California and San Fran- 

 ciscoj Ltr. Ralph Silliraan canvassed the possibilities of obtaining young 

 pilchards in Washington and Oregon. ISr. 0. E. Sette, in charge of the 

 pilchard investigation, gave advice and criticism throughout the entire 

 course of the study, 



IJr. \\'illiara, Bowen, microscopic technician of Stanford UniveiTsity, 

 supervised sectioning and staining of the scales. Preparation of the 

 scales and otoliths for microscopic examination, subsequent clerical work 

 on the statistical processes, and the preparation of graphs were done 

 by !/«■. P. A. Projects 702-3-1 and 10917, respectively, Microtechnical 

 and clerical work was done by N. Y. A. assistants, furnished through 

 the Stanford Student Employment Office,* and Stanford University has gen- 

 erously provided the working quarters of the South Pacific Investigation, 

 giving the staff free access to its libraries and, other useful facilities. 



Finally, we acknowledge with gratitude thQ critical reading of the 

 manuscript by Dr. 1". F. Thompson of the International Pacific Salmon 

 Fisheries Commission, and Dr. Frances N. Clark of the California State 

 Fisheries Laboratory, 



S4 



