t'\.\t:nty-eighth biennlm, report. 



59 



*0OOU>i 



iOOCUbi 



IOCX>Ux. 



60° 



S0° 





-j^>,- 



Ai/^i/ir - 



CaKh of o/boco^e >/u/vi4 ta Ocfbbff/2,/S/S comporctf wirh daily mm imom temperature at Santa 



Sarbara for the some p«r>oef 



^•^^^^ timoeroture ^"—— Catttt 



Fig. 12. The catch of albacore varies with the temperature. In this 

 graph, temperature data have been set back three days so that that 

 for July 27, for instance, appears on tlie same ordinate as does 

 the catcli recorded for July 24. 



tuations occur, whether in abundance or in quality; (3) the foretelling 

 of these fluctuations; (4) the analysis of whatever migrations occur, in 

 order that the interdependence of fish of diflierent regions may be 

 known, and (5) the foundation of measures for protection in case 

 depletion should occur. 



Of these purposes, the second, although naturally not of greater 

 importance, must precede all the others. It would be impossible to 

 detect depletion, were the natural changes unknown ; and, as is made 

 very clear in the law under which we work and in our published papers, 

 the conservation of our fisheries must be set above all else. The 

 thorough understanding of the natural changes leads to their foretelling 

 and to the assignment of the proper causes for instances of decline in 

 abundance. The analysis of the migrations is necessary primarily in 



-^^/7i.fart 



Fig. 



13. Comparison of the amount of barracuda, white sea bass, and yellow- 

 tail caught by purse seiners and that taken by other boats. Black : 

 W'efkly landings by purse seiners at San Pedro, 1922. White: Weekly 

 landings by other boats at San Pedro, 1922. 



order that the extent of tlie effect of overfishing or of natural over- 



al)undance in a given locality upon other localities, may be determined. 



It is nevertheless true that the discovery and correct definition of the 



great natural fluctuations in abundance is an end in itself. Thev must 



