62 REPORT OF THE FISH AND GAME COMMISSION. 



needs of the fishery. To quote California Fish and Game, Vol. 6. 

 No. 4 : 



The propfram under wliieh the work has been done contemplates (1) the dis- 

 covery of depletion if it should occur, (2) the discovery of Kvoat natural fluctua- 

 tions in abundance or quality other than those due to over-fishing, (3) the fore- 

 telling of these fluctuations, which in other fisheries have at times caused great 

 damage, (4) the deci])hering of those habits of the species which are of importance 

 to the canner and fisherman, such as migrations, and (7>) 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 very 

 near future, enabling us to make at least provisional answei-s, a thing impossible now. 

 Among these we may list the age and rate of growth, the breeding season, and the 

 interdependence of the sardines in different regions. That the fore-telling of fluctu- 

 ations is not necessary may be seen from the work of the Norwegian fishery authori- 

 ties on the herring. The other elements of the outline given are dependent entirely 

 upon the records we obtain — and we are acquiring the very best possible. 



The most valuable results to be expected from these investigations 

 will be the ability to detect the earliest evidence of depletion so that 

 we can permit the industry to expand without fear of greatly overrun- 

 ning the limit of safety for the future of the iudustry, to detect natural 

 fluctuations in abundance from depletion and to be able to foretell the 

 abundance of the different canning sizes in the next or subsequent 

 years. 



Clam Investigation. 



Since April, 1919, F. W. Weymouth has been devoting a portion of 

 his time to the completion of a survey of the shellfish of the California 

 coast commenced several years previously by AVill F. Thompson. A 

 report is now in the hands of the printer (Fish Bulletin No. 4) embody- 

 ing all the collected data. The primary purpose of the survey has been 

 to put on record the number and abundance of the species of commercial 

 importance and the location and condition of the beds at present being 

 utilized. The scope of the report has been extended by the inclusion 

 of descriptions and figures together with a key for ready identification 

 of some forty species of present or possible commercial value. Hereto- 

 fore no such key has been available, and it is hoped that by this publi- 

 cation campers and amateur clam diggers can be made acquainted with 

 the edible bivalves of the coast. Beside the description and range of 

 each species an account of its habits has been included. Though many 

 collections of attractive and interesting "shells" have been made there 

 are few observations on the varied habits of these mollusks and it is 

 hoped that those recorded in this report may lead to more study of the 

 remarkable ways in which the bivalves are adapted to the diverse con- 

 ditions of life under which they are found. 



In connection with this survey certain important points have de- 

 veloped. One is the need for a more detailed study of the life history 

 of at least some of the more representative and important species. At 



