216 
BULLETIN OF THE BUKEAU OE EISHEBIES 
number. On December 4 there was an average of 494 per square foot. On that date 
a heavy storm strikingly changed the topography of the beach. An extraordinarily 
heavy surf dragged the sand from tlie high beach out into deep water. Certain 
sections of the beach were lowered 4 or 5 feet. Wliile it is natural to assume that a 
great number of the small clams perished, undoubtedly many were carried out into 
deep water where their survival is uncertain. 
A census of the beach immediately after the storm showed very few clams. 
Some places were entirely barren, but an examination of the entire beach gave an 
average of 18 per square foot. During the winter there was a lighter mortality, 
leaving about 16 per square foot when examined the following February. Of these 
survivers very few, if anj', were left the following summer. Thus we see that the 
number of small clams resulting from one spawning is no criterion of the extent 
to which that year class will affect the commercial catch. The records given above 
show the total loss of a very hea^-y set; therefore, a successful spawning does not 
necessarily indicate that the population of the beds will be increased by it. 
The fate of clams removed to tlie area below low tide is questionable. Small 
clams are not found in water deeper than 12 feet, and probably only stragglers 
among the mature clams are found far from the intertidal zone. In the instance 
cited above a great many may have been removed to the area exposed at the lowest 
tides only or bordering these areas. They would then supplement the number al- 
ready there, and might even spread out and return to the higher levels, where they 
might be taken by the diggers. 
The State of California is attempting by a yearlj' census to find the abundance 
of the annual set and to follow the survival of the young of the Pismo clam from 
year to year. This is done by taking all clams from a trench crossing the entire 
beach. The process is repeated at several places in order to obtain a reliable 
average. The clams are then sorted as to age. and the number of each class for 
each meter of trench is recorded. The result of the last census is given by Her- 
rington in a paper which will appear in an early number of the California Fish 
and Game Bulletin (1925). A similar system of annual surveys of the Washington 
beach, supplemented with the examination of the cannery shell piles, would give 
an index of the beach population. The census of the set each year, with an analysis 
of its subsequent effect upon the commercial catch, would make it possible to 
determine the result of fishing, protective measures, and to foretell with some 
degree of accuracy the amount of the commercial catch. 
GROWTH OF THE ADULT 
RING METHOD OF AGE DETERMINATION 
The size at various ages is a matter of very great practical importance in 
various questions, such as the determination of age at sexual maturity and the 
efficiency of protective legislation. Since the absence of direct observation which 
can fix the age has made is necessary to use extensiA^ely the indirect determination 
by " annual rings," a short statement of this method will be desirable. 
