222 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
Is it possible to determine the number of survivals in an animal like the lobster? 
We can not fix the number positively, but we can fix a maximum limit beyond which 
we may be sure, reasoning from known facts, the number of survivals can not pass. 
By survivals I mean the number of eggs which develop and grow up to maturity, for 
death, at whatever point occurring at this period, means evil to the species in exactly 
the same degree. In order to maintain the species at an equilibrium it is only neces- 
sary that each female produce two adults in the course of her life, whether it be long 
or short. Then there will be neither increase nor diminution, but the species will hold 
its own. If more than two adults are raised from the eggs of each female in a given 
period, then the species must increase; if less, it must diminish. Under present con- 
ditions it is generally agreed that the lobster is declining, which means that each 
adult female produces less than two sexually mature individuals to take the place of 
their parents. 
Spawning lobsters may produce as few as 3,000 eggs and as many as 90,000 or 
100,000, the number of eggs laid increasing very rapidly in proportion to the increase 
in size, according to the law given above. While a 10-inch lobster produces on the 
average 10,000 eggs, a 12 inch lobster bears twice as many, and a 14-inch lobster nearly 
four times as many, or 40,000. Although sexually mature lobsters can produce eggs 
only once in two years, many live to hatch several broods and give rise to hundreds 
of thousands of young. Bemembering that females become mature when from 8 to 12 
inches long, to be on the safe side we may assume that on the average they mature at 
the length of 10 inches. A 10-inch lobster produces on the average about 10,000 eggs. 
Considering all the facts, it is erring on the safe side to assume that the average 
number of eggs produced by all lobsters which have spawned is 10,000. It is probably 
much greater than this. It can not certainly be less. Since it is necessary that only 
two of this number should survive to maintain the species at an equilibrium, we can 
get some idea of the amount of destruction which is wrought under existing circum- 
stances. A survival of 2 in 10,000 or 1 in 5,000 is probably even greater than actually 
occurs. The remainder of this large number must be destroyed in one of two ways, 
by nature and by man, who assists nature in this work after the young are able to be 
caught in his traps. It can make no difference in the result what the agent of this 
destruction is, whether it is the ocean current, the storm lashing the rock-bound 
coast, the codfish, or man, except in so far as the evil wrought by man may be under 
control. If we award to man one-half of the blame, this would imply that instead of 
a saving of 2 in 10,000, under nature there might be a survival of 4. But such a 
survival would lead to a greater increase in the species than could probably ever occur. 
What, then, is the ratio of the number of eggs laid to the number of young 
reared? Allowing that man does one half of the work of destruction — which he 
certainly does not — and allowing an average total production of 10,000 eggs to each 
female that has spawned at all — undoubtedly too small a number — the species would 
be maintained under nature by a survival of 2 in every 10,000, or 1 in 5,000, if man 
did not interfere. A survival of 4 in every 10,000, or 2 in 5,000, would keep up the 
present stock with the added drain which man puts upon it. Considering that the 
fishery is declining, it can be maintained with a considerable degree of confidence 
that a survival of 1 in 5,000 is a very liberal allowance. 
These considerations have a direct bearing upon the efficiency of the present 
methods of artificial propagation, which consist of stripping off the eggs from the 
