THE AMERICAN LOBSTER. 
25 
to swing the other way, and the lobsters move into deeper water or to a rocky 
bottom. This outbound movement is continued during the months of September and 
October, but, as already pointed out, it is by no means general and is probably more 
pronounced in cold than in mild seasons. 
Table 2. — Showing the monthly mean temperature of the ocean at Woods Hole, Massachusetts. 
Computed from daily observations of temperature of bottom, taken at high water, ^ 
at United States Fish Commission Station, by Yinal N. Edwards. 5 
Time. 
1889. 
1890. 
1891. 
1892. 
1893. 
Means 
1889-93. 
of. 
36. 9 
o F . 
38. 8 
of. 
33. 0 
°F. 
36.8 
°F. 
29. 5 
OF. 
35. 0 
32.1 
39.9 
34.7 
31.2 
29. 7 
33.5 
March 
35. 6 
36. 6 
35. 3 
33.2 
32.5 
34.6 
42.7 
43. 2 
44. 3 
42. 6 
40. 0 
42.5 
53.2 
52.4 
51. 0 
51.2 
52. 7 
63. 3 
62. 0 
61. 1 
62. 1 
61. 2 
62. 1 
68. 7 
69. 3 
64.8 
68.0 
69. 5 
68. 1 
70. 6 
71. 1 
70. 9 
73. 3 
70.9 
71.4 
67. 1 
68. 5 
61. 1 
66.9 
67. 5 
66.6 
55. 3 
59.0 
59. 6 
58.6 
60.5 
58. 6 
49.9 
48.0 
47.4 
48.3 
52.4 
49.2 
43.0 
36.7 
43.5 
37.2 
40. 9 
40.2 
51.7 
52. 2 
50.6 
50. 8 
50.5 
The mean temperature of the water at Woods Hole, Massachusetts, was 52.68° F. 
for May, from 1889 to 1893 (v. table 2), the extremes of monthly averages varying from 
51° in May, 1892, to 55.6° in May, 1889, and the range was similar for the latter part of 
October during the same period. The greatest heat is reached in August (70.6°, 1889, 
to 73.3°, 1892), while the temperature of the water in September is but little lower 
than that of July. In the latter part of October the water becomes cooled to 
about the same degree it had reached during the latter half of May. We may 
therefore conclude that the optimum temperature for the lobster lies between 50° and 
60° F. When the temperature of the sea water marks 50° to 55° in spring large 
numbers of these animals have already begun to creep nearer the shores into 
shallower and warmer places, and again in the fall, when the temperature has fallen 
to this point, many have already been impelled to recede to greater depths. Many 
lobsters, however, remain in the relatively shallow water of harbors all winter, a fact 
which has already been emphasized; so it is certain that temperature is not the only 
influence at work in directing these semiannual movements. The question of food 
may be of equal or even greater importance. 
The winter catch of lobsters in relatively shallow water is often considerable. 
Thus, on December 13, 1888, Mr. Edwards set two lobster pots 1 in the harbor of Woods 
Hole, in about 25 feet of water, and hauled them fifteen times during the month, 
taking an at^erage of 15 lobsters to a haul, or 223 in all. In December, 1889, 54 
lobsters were taken in a fyke net at the head of the harbor, 36 were captured in 
January, while none were caught in February. 
In December, 1893, Mr. Edwards began to collect more systematically facts relat- 
ing to the winter habits of the lobster, the results of which are discussed in another 
place (see pp. 30, 31, 44, 45, 79, 80). Five traps were set in the harbor of Woods Hole 
in 25 to 29 feet of water on rocky bottom (it being impossible to get any lobsters on the 
mud); 224 were taken in December, 501 in January, 246 in February, and 318 in 
In these and all other traps used, the space between the laths varied from 1 to 1|- inches. 
