during the year and are highest in summer and fall and lowest in late 

 fall and spring. The age structure of the clam population at Monterey 

 Bay Academy is comprised of five classes, four of which appear to 

 represent year classes. 



VII. SUMMARY 



1. Pismo clams in Monterey Bay are distributed between the Salinas 

 River mouth and Santa Cruz. There are no clam beds south of the Salinas 

 River. 



2. The highest densities of clams occur in the intertidal zone or 

 in the shallow subtidal zone. There were no extensive subtidal clam 

 beds. 



3. Intertidal Pismo clams appear as high as +2.6 feet above MLLW and 

 the different size classes do not show a vertical separation. 



4. The dispersion pattern of most intertidal clams is random. 



5. The presence and absence of clams on beaches are statistically 

 correlated with the slope of the beach and the grain size. Clams are 

 found in beaches with slight slopes and smaller grain sizes. 



6. Pismo clams have a 1:1 sex ratio and mature in their second year 

 at about 20 millimeters in length. 



7. The principal spawning period for Pismo clams in Monterey Bay is 

 September and October. Some spawning also occurs during the summer 

 months . 



8. Juvenile Pismo clams grow more rapidly than adults at all times 

 of the year. 



9. The growth rate of clams varies at different times of the year. 

 Growth is more rapid in late summer and early fall than in spring and 

 late fall. 



10. The growth rate is slower in Monterey Bay than southern 

 California. 



54 



