218 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
problem is involved. We must know tlie state of the fishery and the principal facts 
pertaining to the life and habits of this animal. 1 
Until within a few years the life history of the lobster was very imperfectly known, 
and this ignorance has nowhere been more clearly reflected than in the attempts to 
cure existing evils by legislation. Knowing the general facts of the case, we must 
interpret them in accordance with the principles of science and common sense. The 
principal facts are these 2 : 
(1) The fishery is declining, and this decline is due to the persistence with which 
it has been conducted during the last 25 years. There is no evidence that the animal 
is being driven to the wall by any new or unusual disturbance of the forces of nature. 
(2) The lobster is migratory only to the extent of moving to and from the shore, 
and is, therefore, practically a sedentary animal. Its movements are governed chiefly 
by the abundance of food and the temperature of the water. 
(3) The female may be impregnated or provided with a supply of sperm for future 
use by the male at any time, and the sperm, which is deposited in an external pouch 
or sperm receptacle, has remarkable vitality. Copulation occurs commonly in spring, 
and the eggs are fertilized outside the body. 
(4) Female lobsters become sexually mature when from 8 to 12 inches long. The 
majority of all lobsters 10J inches long are mature. It is rare to find a female less 
than 8 inches long which has spawned, or one over 12 inches in length which has never 
borne eggs. 
(5) The spawning interval is a biennial one, two years elapsing between each 
period of egg-laying. 
(6) The spawning period for the majority of lobsters is July and August. A few 
lay eggs at other seasons of the year — in the fall, winter, and probably in the spring. 
(7) The period of spawning lasts about six weeks, and fluctuates slightly from 
year to year. The individual variation in the time of extrusion of ova is explained 
by the long period during which the eggs attain the limits of growth. Anything 
which affects the vital condition of the female during this period of two years may 
affect the time of spawning. 
(8) The spawning period in the middle and eastern districts of Maine is two weeks 
later than in Vineyard Sound, Massachusetts. In 1893 71 per cent of eggs examined 
from the coast of Maine were extruded in the first half of August. 
(9) The number of eggs laid varies with the size of the animal. The law of produc- 
tion may be arithmetically expressed as follows: The number of eggs produced at each 
reproductive period varies in a geometrical series , ichile the length of lobsters producing 
these eggs varies in an arithmetical series. According to this law an 8-inch lobster 
produces 5,000 eggs, a lobster 10 inches long 10,000, a 12-inch lobster 20,000. This 
high rate of production is not maintained beyond the length of 14 to 10 inches. The 
largest number of eggs recorded for a female is 97,440. A lobster 10£ inches long 
produces, on the average, nearly 13,000 eggs. 
(10) The period of incubation of summer eggs at Woods Hole is about ten months, 
July 15-August 15 to May 15-June 15. The hatching of a single brood lasts about a 
week, owing to the slightly unequal rate of development of individual eggs. 
1 In discussing this subject I have not attempted to discriminate between conditions which may 
exist in the United States and the Maritime Provinces. The questions to he considered have primarily 
a general significance. 
J For further details see The American Lobster, Bull. U. S. F. C. 1895, pp. 1-252. 
