THK AMKIMCAN LOBSTEK. 



25 



to s\vin»- 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. 



Tablk 2. — Showing the monthly mean temperature of tin- ocvun at ll'oixls Hole, Massachusetts. 



\ i Computed from daily observations of tomporatnro of bottom, I a ken at liigli water, I 

 I al United Stairs Fisli Commission Station, by Vina) N. Edwards. 5 



Time. 



January 



February 



March 



April 



May 



June 



July 



August 



September 



October 



November 



December 



learly mean 



1889. 



1890. 



1891. 



1S92. 



1893. 

 °F. 



Means 

 1889 93. 



'/■'. 



°F. 



F. 



F. 



°F. 



30. n 



38. S 



3::. o 



36.8 



29.5 



35.0 



32. 1 



39.!) 



34. 7 



31.2 



29. 7 



33. 5 



35.0 



3(1. 



35. 3 



33. 2 



32.5 



34. 



42.7 



43.2 



14.3 



42.0 



40.0 



42. 5 



55. G 



53.2 



52. 1 



51.0 



51.2 



52.7 



<;:s. 3 



02.0 



01.1 



62.1 



61.2 



62. 1 



68.7 



09.3 



04.8 



08.0 



69.5 



08.1 



70.0 



71.1 



711.9 



73.3 



70.9 



71.4 



07.1 



08. 5 



01. 1 



00.9 



07. 5 



00.6 



55. :i 



59.0 



59.0 



58.0 



60.5 



58. 



40.9 



48.0 



47. 4 



48.3 



52.4 



49.2 



43.0 



30.7 



43.5 



37.2 



40.9 



40.2 



51.7 



52. 2 



50.0 



50.8 



50.5 







The mean temperature of the water at Woods Hole, Massachusetts, was 52.08° F. 

 for May, from 1889 to 1S93 (v. table 2), the extremes of monthly averages varying from 

 51° in May, 1892, to 55.0° 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 (70.0°, 18S9, 

 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 

 00° 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 ' in the harbor of Woods 

 Hole, in about 25 feet of water, and hauled them fifteen times during the month, 

 taking an average of 15 lobsters to a haul, or 223 in all. In December, 1S8!>. 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 Dole 

 in 25 to 29 feet of water on rocky bottom (it being impossible to get any lobsters on the 

 mud); 221 were taken in December, 501 in January, 240 in February, and 34S in 



In these and all other traps used, the space between tho laths varied from 1 to 1, inches. 



