

40 





38 





36 





34 





32 



:•' 



30 



n 



28 



# 



26 







o 



24 



to 



Z 



22 







20 







d 



18 



> 





z 



lb 





14 



T 





u 



IV 







< 



10 





8 





b 





4 





2 









- 



1- 



(A) 



-7997353 627*43955 b4894 X -.0000048900 x" 

 p =-88747 



1965 



1970 



G 

 1968 

 



1975 







1971 1973 



- 





p 2 = 78780 





1963 

 O 

 O 

 1966 



O 1964 



--"1969 





3 ° 



- 





1948 

 O 





»6I 1962 X 



I960 °X 

 O / 











- 





' 



949 



C 



/ o 1959 











- 





1950 





1958 

 O 











- 





1951 /l952 

 / ; 



1953 







1955 



1954 

 OO 

 195? 











- 







C 

 1956 

















1 1 ! 









1 







100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 

 NUMBERS OF LICENSED DIGGERS 



38 



36 



34 



32 



30 



<g 28 



O 26 



? 24 



O 22 



K> 20 



o 



IS 











i 



16 



z 



14 





17 



T 





y 



11 



< 





u 



8 





6 





4 





2 









Y = 



(B) 



-27133642.52 • 89325 35742 X -3365237215 X 2 







IP 





p = 92617 



p ; = 85780 "*% 



1966 



1964 

 O 



1965 ' 



"©JO 19*5 



1971 "**" 

 O 





1961 / 

 / 195 



/o 



1967 



,91968 



t968 



1972 

 O 





ra56/,954 1957 



vbwo ,958 









- 



/ 1955 

 „. 1952/ O 



"o* y 











/S43 



«"/ ° so 



r O 









100 200 300 400 500 bOO 700 800 900 1000 1100 1200 1300 1400 1500 1600 

 NUMBERS OF LICENCED DIGGERS 



76 

 72 











(0 









1973 

 O 



68 



_ Y = -24287545 98 



•9518444915 X -000011018 



x 4 





: ■' 





64 

 ./> 60 

 2 56 



P = 



93854 









1963 



O 



O 



1966 



/1967 



igis ,9 ° 75 



1969 



1971 t^Nfc. 



1974 ^* 



O 



(?-- 



88085 















1972 



5 52 











,*■»„« 



















1960 / 











u. 48 



- 









o / 











o 





















44 



- 



















Z 40 



_ 









/ 1959 

 / ° 











o 





















- 36 



- 







































5 32 



- 









1948 / 











Z 28 



- 









□ / 





















/ 1958 











^ 24 











/ ° 











X 











/1953 oot957 











£20 











/O 1954°° 

 / O 01956 











u 16 



- 





': 51 

 3 



950 

 o 



/i949 



^952 1955 











12 



- 



















8 





















4 



- 

















i 



100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 

 NUMBERS OF LICENSED DIGGERS 



Figure 16.— Yield-eiTort curves: (A) bloodworms, (8) sandworms, (C) 

 combined. 



50 



