TWENTY-SEVENTH BIENNIAL REPORT. 77 



or scarce, as we now will be able to do, will be of benefit to the eanners. 

 It will also be of benefit to them to know that a scarcity is due to 

 natural causes and not to overfishing. 



The sardine, it has been found, grows rather rapidly in lengtli at 

 first. At the end of the first year's growth they average not quite four 

 inches in length ; at the end of two years about six and three quarter 

 inches ; at the end of three years about eight and one-quarter inches ; 

 Avhile at the end of four years they reach a length of about nine 

 inches. From the growth curve established from these known figures 

 the age of the larger sizes can be estimated approximately. The largest 

 sizes may be ten or twelve years old. The growth curve of our sardine 

 is similar to that of the European sardine. Our sardine is also similar 

 in its spawning habits, in that the spawning season extends over 

 several months of the spring and summer and in that the spawning 

 sardines leave the coast and proba])ly spawn well off shore. 



The sardine work had not progressed very far before it became 

 evident that there were several factors which influence the size of the 

 sardines taken by the fishermen. A great deal of work has been done in 

 determining the effect of these factors and this work will be treated 

 fully in the report of the work now about completed. 



The influence of these other factors on the size of the fish in the 

 catch would probably not have been detected had samples of the 

 catch been taken only a few times a month as has been done in Europe 

 in similar work. In fact entirely erroneous conclusions could have 

 been arrived at. This led to an investigation by Mr. Sette to determine 

 the error involved in different methods of sampling. This work is 

 a contribution of considerable value to the methods employed in fislieries 

 investigations and besides casting doubt on some of the conclusions 

 arrived at through insufficient sampling in Europe, it shows how large 

 the samples should be and how freciuently they should be taken. 



Daily samples of the catch have been taken over a period of two 

 years in order to work out and determine the seasonal fluctuatimis in 

 size and also the fluctuations in size within the lunar periods and also 

 to explain the causes of these fluctuations. That these factors are 

 important is shown by the fact that the rate of growth in this instance, 

 and the dominance of year classes could not have been determined 

 without knowledge of the fluctuations in the size of the fish tak(>ti l)y 

 fishermen during different phases of the moon. After this season 

 samples need be taken only at intervals of twice a week at [Monterey 

 as was done the present season at San Pedro, and on that account the 

 work will be simplified and reduced to a large extent and i1 will be 

 necessary only to follow the abundance of the year classes as is now 

 being done in the case of the albacore. We will then be able witli 

 our present force to take up tlie investigati()n of other important 

 fisheries which are in danger of depletion, such n^ the bnrrnendn and 

 white sea bass. 



PURSE SEINE INVESTIGATION. 

 We mentioned in our last report how purse seine fishing had been 

 introduced into Southern California mainly for the purpose of catch- 

 ing blue-fin tuna. It was complained by other fishermen that these 

 boats in using their nets for other kinds of fish ejiused great waste, 



