FLUCTUATIONS IN THE SUPPLY OF HERRING 
21 
In gaging the changes in efficiency of the individual boats of the fleet, it is 
extremely difficult to translate changes in size, speed, seaworthiness, age, etc., into 
terms of relative ability to deliver quantities of fish at the plant. In addition there 
is no assurance in comparing two types of vessels in 1929, for example, that precisely 
the same conditions held in 1922. 
In a year when fishing was con- 
ducted at a distance, speed and 
size might be the paramount fac- 
tors; in outside waters seaworthi- 
ness would play a part; in years 
of scarcity, when each haul netted 
but few fish, the larger vessels 
might conceivably catch less than 
the smaller, because of greater 
difficulty in maneuvering. 
In order to discover whether 
the efficiency of the vessel depends 
upon size, the total monthly 
catches have been correlated with 
the net tonnage of the vessel, the 
coefficient of correlation being cal- 
culated from ungrouped data. 
(Table 2.) An inspection of the 
table shows a great variation in the 
value of the coefficient of corre- 
lation. In only 6 out of 23 co- 
efficients is the correlation significant. Of these 6, the significance of the negative 
coefficient based on only 9 pairs of items must be regarded as very doubtful. 
Table 2. — Correlation between net tonnage and total monthly catch of purse seine boats 
60 
SO 
40 
k 
b- 
/o 
/ 
/ 
/ 
N 
/ 
/ 
/ / 
/ 
/ 
— A 
/ 
/ 
/ 
— / 
/ 
/ 
/ 
kv 
rv 
/ X 
/ 
/ 
✓ 
l / 
/ 
Z'92'3 
/S2S~ 
/32P r 
/323 
Figure 4.— Showing the percentages of the fleet included in different 
size categories from 1923 to 1929. Solid line with circles, less than 25 
net tons; solid line without circles, 25 to 29 net tons, inclusive; dotted 
line without circles, 30 to 34 net tons, inclusive; dotted line with circles, 
over 34 net tons 
Month and year 
Number 
of pairs of 
related 
items 
Mean 
catch in 
barrels 
Mean net 
tonnage 
Pearso- 
nian coef- 
ficient of 
correla- 
tion 
Probable 
error of 
coeffi- 
cient of 
correla- 
tion 
Regres- 
sion of 
catch on 
tonnage 
NORTH 1 
June, 1927- 
26 
1, 598 
30.4 
0.803 
2 0.05 
195.7 
June, 1928 
28 
2,597 
33.4 
.427 
2 . 10 
49.2 
June, 1929 . 
18 
3,112 
35.2 
—.218 
.15 
July, 1927 
23 
2,120 
30.7 
.211 
.13 
44] 1 
July, 1928 — 
26 
1, 647 
-.228 
.13 
21.0 
July, 1929 
18 
1, 674 
35.2 
-. 157 
.15 
36.0 
August, 1927 
9 
1, 671 
30. 4 
-.065 
.22 
10.0 
August, 1928 . __ 
23 
1, 398 
35.0 
-. 355 
.18 
40.5 
August, 1929 
12 
*rei5 
36.0 
— . 202 
.19 
64.2 
September, 1928, 
9 
2,022 
38.4 
-. 615 
2 . 14 
71.8 
September, 1929 
5 
4,894 
35.4 
-.626 
.18 
1,003.9 
SOUTH 2 
June, 1927 
23 
1,940 
31.4 
.193 
.14 
33.6 
June, 1928 
30 
3,018 
33.3 
-.191 
.12 
36.5 
June, 1929 ... 
July, 1927 — 
30 
2,672 
33.3 
-. 075 
.12 
15.8 
27 
2, 143 
31.3 
.059 
.13 
12.0 
July, 1928 
29 
2,088 
33.1 
-.246 
.12 
32.8 
July, 1929 
29 
1,440 
33.4 
-.178 
.12 
31.8 
August, 1927 
19 
2,637 
31.3 
.412 
.13 
66.1 
August, 1928 _ 
29 
2,005 
33.4 
-.204 
.12 
32.4 
August, 1929 
34 
3,710 
33.1 
.569 
2 08 
September, 1927 
12 
3,195 
33.0 
.469 
.15 
76! 6 
September, 1928 
16 
3,513 
33. 8 
. 688 
2 . 09 
134.6 
September, 1929. _ _ 
34 
5,344 
33.1 
.532 
2 .08 
160.2 
1 Boats delivering to plants north of Point Ellis (Group n and III) . 
2 Coefficient of correlation of probable statistical significance. 
2 Boats delivering to plants south of Point Ellis (Group I). 
