96 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
THE RATE OF GROWTH. 
The question often asked is, How long does it take an adult marketable lobster to 
grow? It is impossible to answer this with certainty, since complete data for solving 
the problem have not been gathered. We can, however, give a tentative answer which 
is probably not far from the truth. 
In order to ascertain the average age of a lobster 10^ inches long (weight, If 
pounds), it would be necessary to know, first, the number of molts which the animal had 
passed through, and, secondly, the time interval between each molt. The number 
of molts can be approximately determined by meaus which I shall presently discuss. 
The time interval can only be ascertained by keeping the animals alive for a period of 
years and carefully recording their growth. Both factors are very variable quantities, 
as I have already shown. The length of one yearling lobster which was raised from 
the egg was only 36 mm., while three other lobsters measured from 35 mm. to 51.8 mm., 
when not over five months old. Lobsters which live in harbors where they find abun- 
dant food undoubtedly grow much faster than those farther from shore. It would 
hardly be expected, moreover, that lobsters kept under artificial conditions would 
grow as rapidly as when free in the ocean. 1 
In table 24 I have recorded the molts of eight lobsters varying from 54 to 1 
inches in length. The actual increase in length varied from 1 inch to 1J inches, and 
the increase percentage (that is, the ratio which the increase bears to the total length 
before molting) from 0.66 to 18.18. The average percentage of increase in all these 
cases is 12.01. 
Table 24. — Increase in the length of lobsters at the time of molting . 
No. 
Date. 
Sex. 
Length 
before the 
molt. 
Length 
afterthe 
molt. 
Increase 
in length. 
Increase 
percent. 
Remarks. 
Inches. 
Inches. 
Inches. 
1 
Oct. 22,1890 
Female . 
6* 
i 
18. 18 
Carapace of molted shell unbroken ; 
preserved a few days after molt- 
ing; gastroliths gone; stomach 
filled with pieces of fish, which 
had been ted to it; carapace 
leathery. Plates 45a and 45 h. 
2 
Oct. 29,1890 
Male 
11 
12 
i 
9. 09 
Carapace unbroken ; preserved im- 
mediately after molting; gastro- 
liths in their sacs in the walls 
of masticatory stomach. See cut 8, 
plate C. For chemical analysis of 
gastroliths, see Appendix II, 
No. 4a of table. 
3 
Nov. 6,1890 
... do 
n 
84 
4 
9. 68 
Carapace unbroken. 
4 
Nov. 10, 1890 
Nov. 11, 1890 
June 8, 1891 
9 
m 
8 
lb 
16. 66 
Do. 
5 
A 
6. 66 
Do. 
6 
... do 
9?S 
101 
Ws? 
13. 13 
Carapace unbroken; measured July 
2. See table 28. 
7 
July 13, 1891 
... do 
111 
12i 
11 
11. 11 
Carapace unbroken ; measured July 
17. See account of molting of this 
lobster, pp. 83-85; also plate B. 
8 
6h 
71 
1 
11.54 
Recorded by Packard (147). 
12. 01 
l The best way to ascertain the growth of the lobster would be to fence in securely with wire 
netting a convenient area in a lobster pound, place a few lobsters in the inclosure, and feed them reg- 
ularly. They should be examined every week and carefully measured. They could be distinguished 
by branding the tail-fan. By selecting lobsters of different sizes (3, 5, 8, 10 inches long), the rate of 
growth at different periods of life could be gradually determined. 
