Although the lobster has been of great value to the New England States
and the British Provinces as a food commodity, but little was known of
its life-history and habits until within the last few years. To this
ignorance has been due quite largely peculiar (and in some instances
useless) laws enacted by some States. The gradual enlightenment of the
public on this subject has borne good fruit, however, and most of the
present State laws are founded on substantial facts instead of
theories. Prof. Francis H. Herrick has been one of the most prominent
of the investigators, and his summary of the present knowledge on this
subject is quoted below from the Fish Commission Bulletin for 1897:
(1) The fishery is declining, and this decline is due to the
persistence with which it has been conducted during the last
twenty-five 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 10-1/2 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 production may be arithmetically expressed as
follows: _The number of eggs produced at each reproductive
period varies in a geometrical series, while 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 16 inches. The largest number of eggs
recorded for a female is 97,440. A lobster 10-1/2 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.
(11) The hatching period varies also with the time of
egg-laying, lobsters having rarely been known to hatch in
November and February.
(12) Taking all things into consideration, the sexes appear
about equally divided, though the relative numbers caught in
certain places at certain times of the year may be remarkably
variable.
(13) Molting commonly occurs from June to September, but there
is no month of the year in which soft lobsters may not be
caught.
(14) The male probably molts oftener than the female.
(15) In the adult female the molting like the spawning period
is a biennial one, but the two periods are one year apart. As a
rule, the female lays her eggs in July, carries them until the
following summer, when they hatch; then she molts. Possibly a
second molt may occur in the fall, winter, or spring, but it is
not probable, and molting just before the production of new
eggs is rare.
(16) The egg-bearing female, with eggs removed, weighs less
than the female of the same length without eggs.
(17) The new shell becomes thoroughly hard in the course of
from six to eight weeks, the length of time requisite for this
varying with the food and other conditions of the animal.
(18) The young, after hatching, cut loose from their mother,
rise to the surface of the ocean, and, lead a free life as
pelagic larvae. The first larva is about one-third of an inch
long (7.84 mm). The swimming period lasts from six to eight
weeks, or until the lobster has molted five or at most six
times, and is three-fifths of an inch long, when it sinks to
the bottom. It now travels toward the shore, and, if fortunate,
establishes itself in the rock piles of inlets of harbors,
where it remains until driven out by ice in the fall or early
winter. The smallest, now from 1 to 3 inches long, go down
among the loose stones which are often exposed at low tides.
At a later period, when 3 to 4 inches long, they come out of
their retreats and explore the bottom, occasionally hiding or
burrowing under stones. Young lobsters have also been found in
eelgrass and on sandy bottoms in shallow water.
(19) The food of the larva consists of minute pelagic
organisms. The food of the older and adult stages is largely of
animal origin with but slight addition of vegetable material,
consisting chiefly of fish and invertebrates of various kinds.
The large and strong also prey upon the small and weak.
(20) The increase in length at each molt is about 15.3 per
cent. During the first year the lobster molts from 14 to 17
times. At 10-1/2 inches the lobster has molted 25 to 26 times
and is about 5 years old.
As the purpose of this article is to deal more particularly with the
commercial side of the lobster question all interested more
particularly in the natural history of the animal are referred to the
following works:
The Fisheries and Fishery Industries of the United States,
sec. I, pp. 780-812.
The American Lobster, by Francis H. Herrick. Bull. U. S. Fish
Com. for 1895, pp. 1-252.