560 
BULLETIN OF THE BUREAU OF FISHERIES 
years. These constants have been compared with the geographical position as 
represented by the distance in statute miles along the coast from Pismo. 
Table 7. — Growth constants of Siliqua patula for the localities considered 
Pismo 
Crescent 
City 
Channel 
Sink 
Copalis 
Massett 
Controller 
Bay 
Karls 
Bar 
Swickshak 
Hallo 
Bay 
Latitude 
Distance from Pismo 
35° 11' 
41° 45' 
46° 58' 
46° 58' 
46° 58' 
53° 20' 
60° 
60° 27' 
58° 5' 
to 
00 
to 
miles.. 
5 per cent survival age 1 
0 
500 
860 
860 
860 
1,380 
2,040 
2, 105 
2, 405 
2,425 
years.. 
5 per cent survival 
4. 40 
7. 90 
7. 00 
7. 00 
8. 85 
9. 55 
11. 00 
12. 05 
13. 40 
15. 65 
length centimeters . 
Average growth 
12. 05 
13.40 
11.40 
12. 00 
14. 40 
13. 70 
13. 00 
15. 95 
16. 00 
15. 70 
centimeters. 
Initial relative growth 
2.74 
1. 69 
1. 63 
1. 72 
1. 63 
1. 43 
1. 18 
1. 32 
1.19 
1. 00 
rate 
Relative growth rate, 2 
5.05 
4. 67 
4. 59 
4.69 
5. 21 
4. 14 
3. 43 
3. 53 
3. 53 
3. 39 
years 
0.25 
0.43 
0. 49 
0.23 
0. 23 
0.56 
0.68 
0.90 
0. 85 
0.88 
1 Given as ring number. To calculate actual age subtract one-half year. 
It is obvious that a satisfactory analysis is impossible at present. The physico- 
chemical factors represented by the environment are imperfectly known for even the 
most studied points on the Pacific coast; and for manj^ of our localities we have no 
information whatever as to tem- 
perature, salinity, hydrogen-ion 
concentration, plankton, or any 
other of the agencies known to in- 
fluence physiological processes. We 
may safely infer that the tem- 
peratures on the southern beds are 
higher and the season of higher 
temperatures is longer than in the 
north, but we can not put this 
into quantitative form. 
The striking fact that many 
features of growth show such high 
correlation with the group of environmental features indicates that a satisfactory 
knowledge would reveal important laws of growth. For the present we can only 
record the suggestive observed relations which can not yet be analyzed. 
The correlations obtained are given in Figure 11. For biological data these 
correlations are strikingly high, ranging from 0.71 to 0.95. The highest of these is 
between age and geographical positions in the sense that clams from the northern 
beds show the longest life or the lowest mortality. The next highest is the negative 
correlation between the initial growth rate and that at two years. Since these con- 
stants are two measures of the same thing, a close relation would be expected and the 
figure indicates that a high relative growth rate in early life is followed by a low growth 
rate in later life and vice versa. 
In consequence, the correlations of the early and late growth rates with other 
constants show similar values but have opposite signs. The highest correlation of 
relative growth rate is with geographical location. The highest initial and lowest 
final values are found at Pismo, the southernmost locality. The next highest correla- 
tions are between relative growth rate and age. A low initial rate and high later rate 
are associated with long life. 
Figure 11 .— Diagram of the five constants derived from growth curves 
with coefficients of correlation for each pair 
