MIGRATIONS OP COD 
89 
also the catches of cod larvae 14 made by the Albatross II along the outer coast of 
Cape Cod. These included a catch on May 28, 1927, off Race Point, of 148 larvae 
3 y 2 to 6 y 2 millimeters long, taken in one haul, and another off Cape Cod Light on the 
same date of 194 larvae which measured 3% to 9% millimeters. It is apparent from the 
size of these larvae that they would be carried beyond the Nantucket region by the 
time they reached the bottom stage. 
It is safe to assume that most of the eggs spawned north of Cape Cod hatch in 15 
to 30 days, depending on the season and, therefore, the temperature. If approxi- 
mately 50 days are allowed for the development of the larvae and fry, it can be seen 
that spawning grounds located 65 to 80 “drift days” away and in line with the south- 
erly drift are well situated for supplying southern Massachusetts with fry. Excep- 
tions, of course, would occur, for the velocity of drift might be greater some months 
than others; eggs spawned early in the season might hatch in as little as 10 days; 
and delays en route, such as might be caused by eddies, would enhance or retard 
the chances of fry reaching the shoals, depending upon how far they had to drift. 
Along the course of the southerly drift there are various important spawning 
grounds. Farthest north and east, between Cape Elizabeth and the Bay of Fundy 15 
the grounds are scattering and small, but in the aggregate a large number of cod eggs 
are probably produced there. More important spawning grounds are located between 
Cape Ann and Cape Elizabeth (chiefly in Ipswich Bay), and others between Cape 
Ann and Cape Cod. (Fig. 27.) 
Although cod spawn throughout the winter in most localities, the time when the 
height of egg production occurs may vary even on two grounds close together. Thus 
Bigelow (1924, p*. 422) shows that on the north side of Cape Ann ripe fish are not 
common until January or February and much of the spawning occurs from February 
to April, while off Plymouth, only 50 miles distant, the important part of the season 
usually is in January and February. Fish (1928, p. 290) found considerable spawning 
taking place off Plymouth as early as November 12, in 1924. Between Cape Eliza- 
beth and the Mount Desert region most of the spawning takes place from March 
to May. 
Variation in the incubation period of the eggs (see Table 33), according to tem- 
perature, makes it pertinent to consider the approximate conditions which exist 
over the spawning grounds which lie in the path of the drift toward Nantucket 
Shoals at the time of spawning. 
Table 33 .-—Period, of incubation for cod eggs ° 
Water temper- 
ature 
Days 
Water temper- 
ature 
Days 
Water temper- 
ature 
Days 
Water temper- 
ature 
Dajs 
° F. 
° C. 
° F. 
° C. 
° F. 
° C. 
° F. 
0 C. 
31 
-0.6 
50 
36 
2.2 
25 
41 
5.0 
16 
46 
7.8 
11 
32 
0.0 
40 
37 
2.8 
23 
42 
5. 5 
15 
47 
8.3 
10-11 
33 
+0.6 
35 
38 
3.3 
21 
43 
6. 1 
14 
34 
1. 1 
31 
39 
3.9 
19 
44 
6. 7 
13 
35 
1.7 
28 
40 
4.4 
17 
45 
7. 2 
12 
« From A Manual of Fish Culture, p. 206, in Report U. S. Commissioner of Fisheries, Pt. XXIII, for 1897. 
“These larvae were discovered among plankton hauls made by O. E. Sette during mackerel investigations. 
■^Because of the unusual physical conditions of the water in the Bay of Fundy, larvae from pelagic eggs are rare there. (See 
Huntsman, 1918c, p. 65.) 
