224 
BULLETIN OF THE BUREAU OF FISHERIES 
There are only two records of C. ty pious in the gulf in July — one off Cape Elizabeth 
on the 29th (station 10019) and the other in Casco Bay on the 31st (station 10020) — 
both in 1912. The records point to a notable increase in August, when it occurred at 
23 per cent of the stations (7 out of 31) in 1912, 40 per cent (8 out of 20) in 1913, 
and at 2 out of 11 in 1914. It is most regularly distributed in the gulf during autumn 
and early winter, occurring at 60 per cent of the September stations and 66 per cent 
of the October stations in 1915 and at about 60 per cent of the stations for December, 
1920, and January, 1921. The local abundance of the species, as well as the generality 
of its distribution, likewise increases during late summer and autumn, mounting 
to an average of about 1,000 per square meter for August, 1913 (counting only the 
stations where it is actually recorded east and north of Nantucket), about 5,300 for 
September, 1915 (maximum 18,200 in Massachusetts Bay on the 29th), and to about 
8,637 during that October (maximum 24,450 in Massachusetts Bay on the 27th). 
Off Marthas Vineyard on October 22, 1915, the numbers per square meter ranged 
from about 58,400 near shore (station 10331) to slightly more than 12,000 on the 
outer part of the continental shelf (station 10333). Even at its season of maxi- 
mum abundance, C. typicus is usually a minor element in the plankton of the gulf, 
averaging only 7 to 9 per cent of the total copepod population at the stations where it 
occurred in September and October, 1915 (table, p. 298). Occasionally, however, it 
may dominate locally near shore — witness 40 per cent of this species in Massachusetts 
Bay on September 21 of that year (station 10321) — but probably this never happens 
out at sea in the gulf. 
C. typicus constituted so small a percentage (1 to 8 per cent) of the scanty 
catches of copepods made during the December and January cruise of 1920 and 1921 
as to suggest a shrinkage in its numbers during the late autumn. 
The numbers of C. typicus present per square meter are further interesting as 
proving the Massachusetts Bay region generally and the waters off Cape Cod its 
chief centers of abundance in the gulf during the late summer and autumn. In late 
winter and spring the largest catches have been made in the western and eastern sides 
of the basin — 2,600 per square meter at the former locality on February 23, 1920 
(station 20049), and 41,100 per square meter near German Bank on May 6, 1915 
(station 10270). It is also worth noting that this last was the richest catch of C. 
typicus that has ever been recorded east of Nantucket, though at a time of year when 
the species occurs only irregularly in the gulf and usually in very small numbers. 
Breeding. — No observations have been made on the breeding of this species in the 
gulf, but the fact that its chief center of local abundance lies off Massachusetts Bay, 
whereas summer immigrants, whether of northern or of Tropic origin, enter chiefly 
via the eastern side, is strong evidence that the stock is maintained by local reproduc- 
tion, aided little, if at all, by immigration. The presence of this species within the 
gulf throughout the year tends to corroborate this. Seasonal fluctuations point to 
summer as the chief breeding season, as does the fact that in 1915 the autumnal 
multiplication of C. typicus and C. hamatus was preceded by an abundance of larval 
copepods of some sort (see table, p. 298). With only one period of abundance 
annually, and that well-marked in contrast to the scarcity of the species during the 
other months, it is safe to assume one chief breeding period for it yearly. 
