94 
BULLETIN OF THE BUREAU OF FISHERIES 
nearly correct picture of the summer state results from the assumption that the 
entire catch of zooplankton in the vertical net at that season was taken below 10 
meters at each station, but that it was only one-third as dense as the ostensible 
volume per cubic meter below 100 meters, and correspondingly concentrated above 
that level. The results of such a calculation for 1914 are given in the following table: 
Volumes of plankton per cubic meter ( in cubic centimeters ) between the depths of 10 and 100 meters, 
July to August, 191 4 l 
Locality 
Date 
Station 
Total 
depth in 
meters 
Volume 
per cubic 
meter if 
calculated 
as above, 
in cubic 
centi- 
meters 
Volume 
per cubic 
meter if 
uniformly 
distrib- 
uted, in 
cubic 
centi- 
meters 
Off Cape Cod __ 
July 19 
do 
10213 
110 
2. 2 
1.90 
Southwest Basin. _ 
10214 
175 
1 
.68 
Georges Bank: 
Northwestern part . 
July 20 
do 
10215 
70 
1 
.85 
Southwestern part 
10216 
70 
. 5 
.43 
July 23 
...do 
10223 
75 
2. 6 
2. 40 
Northeastern part 
10224 
55 
5.3 
4. 30 
Northeastern part 
July 24 
July 23 
July 24 
July 25 
-do.. .. 
10226 
85 
2. 6 
2. 30 
Southeast Deep.. 
10225 
260 
.2 
. 12 
Eastern Channel _ 
10227 
220 
. 4 
. 23 
North Channel-.. 
10229 
100 
1.9 
1. 70 
10230 
50 
3.5 
2. 80 
Do..* 
Aug. 11 
Aug. 12 
do 
10243 
55 
2.2 
1.80 
.30 
1. 
10244 
50 
.4 
Northeast trough 
10246 
190 
1.7 
10247 
30 
. 5 
.33 
Off Mount Desert Rock 
Aug. 13 
10248 
190 
.7 
.52 
Eastern Basin.. 
10249 
220 
.8 
. 48 
Off Penobscot Bay 
Aug. 14 
Aug. 22 
10250 
145 
3. 3 
2. 40 
Off Cape Ann 
10253 
140 
.6 
.42 
10254 
260 
1. 4 
.77 
Center of gulf near Cashes Ledge 
Aug. 23 
10255 
175 
. 6 
.40 
1 For tables of the volume per cubic meter for July and August, 1913, and for May to October, 1915, see Bigelow, 1915, p. 328, 
and 1917, p. 314. 
The most instructive feature of this table is its demonstration that, although 
the total amount of plankton present below any given unit of the sea’s surface rules 
larger in the deeper parts of the gulf than in the shallower water, as a rule it is most 
densely aggregated in the coastal belt within the 150-meter contour and in the 
shallows of Georges Bank, no matter which calculation be employed. This was 
true, also, in the summer of 1913. In fact, the northeastern part of the deep basin, 
where the water has proved very productive on several occasions in summer and 
early autumn, as well as in late spring, has been the only exception to this rule for 
any time of year. 
Enough hauls have now been made to show that the zooplankton (especially 
the Crustacea) is usually most densely congregated, summer after summer, in four 
rather definite areas — (1) over the eastern end of Georges Bank, (2) in the shoal 
water south of Cape Sable, (3) in the deep northeastern basin, and (4) off Massachu- 
setts Bay out to the 100-meter contour (fig. 39). At the other extreme the western 
and southern parts of the deep basin and the coastal belt inside the 100-meter contour 
east of Penobscot Bay have never yielded as much as 2 cubic centimeters of plankton 
to the cubic meter of water at any season by either mode of calculation, nor has the 
water over the coast bank west of Nova Scotia proved productive except for the 
Pleurobrachia swarms so characteristic of that locality (p. 19). 
