194 
BULLETIN OE THE BUREAU OF FISHERIES 
of the vertical hauls, and three-fold on Browns, but decreased by about that same 
proportion in the eastern channel, a change probably too small to be significant. 
In the western basin the average number of C. Jinmarchicus at all the stations was 
practically the same in April (about 13,000 per square meter) as in February and 
March (about 12,000), but an equalization of the species had taken place. 
The augmentation of the stock of C. Jinmarchicus that takes place during the 
later spring is the most notable event in the seasonal history of the animal plankton 
of the gulf. In 1920 this multiplication of Calanus began in the Massachusetts 
Bay-Cape Cod region by the middle of April, as I have just pointed out (p. 41), 
and by the first week in May it had progressed sufficiently to raise the numbers per 
square meter to an average of 19,000 for all the stations from near Cape Ann out 
across the western end of Georges Bank. 
In 1913 no notable increase of Calanus was observed in Massachusetts Bay 
until the first week in May; this was first evidenced in Gloucester Harbor, where on 
the 3d Welsh found the water "reddened for areas of about a square yard, several 
yards apart, with what proved to be swarms of copepod nauplii and young copepods. 
And on the 17tli, hauls off Magnolia, Mass., yielded great numbers of small copepods, 
chiefly C. jinmarchicus. ” (Bigelow, 1914a, p. 407.) 
In the spring of 1915 the vernal augmentation of Calanus either commenced earlier 
in the season than in 1913 or 1920, or proceeded more rapidly, for on May 4 the 
vertical net took it at the rate of 459,900 per square meter off Gloucester (station 
10266), this being the greatest number ever counted in the gulf. It was only slightly 
less numerous in the eastern basin off German Bank on the 6th, and the average 
number per square meter for a belt right across from the Massachusetts Bay region 
in the west to German Bank and Lurcher Shoal in the east was about 150,000. It 
is probable that the multiplication of Calanus does not proceed so rapidly in the 
northern parts of the gulf, though it may commence there as early as mid-April (p. 
41), the June counts off Penobscot Bay and eastward 98 ranging from only 7,500 to 
21,000 per square meter for 1915. Probably a fairer concept of the late spring status 
of the species, both numerically and regionally, would result from the union of the 
May with the June counts despite the disparity in date, which gives an average of 
about 96,000 per square meter for the whole gulf north of a line Cape Cod- Cape 
Sable, or about 63,000 if the vertical hauls for May, 1920, be included. Although 
this calculation may very well be 100 per cent out of the way, due to faults inherent 
in the process of estimation and to the paucity of stations, at least it shows that the 
stock is many times as great in late spring and early summer as it is in winter or 
during March and April. 
It is not possible to follow the seasonal fluctuations of C. jinmarchicus at close 
intervals through the summer for want of sufficient data for late June and July, nor 
have the percentages in which the species occurred been determined for the vertical 
hauls for August, 1912 or 1914. This was done for the vertical hauls for August, 
1913 (Bigelow, 1915, p. 286), and for most of the horizontal hauls at various depths 
for stations for 1912 and 1914, when the total numbers of copepods were calculated 
from verticals. With Calanus so greatly preponderating over all other copepods 
88 No vertical hauls were made in this part of the gulf in May. 
