REGARDING THE RATE OF GROWTH OF THE 

 AMERICAN LOBSTER. 1 



PHILIP B. HADLEY. 



\_From the Biological Laboratory of Brown University and the Experiment Station of 

 the Rhode Island Commission of Inland fisheries. ~\ 



At the present time when artificial propagation is bidding fail- 

 to at least partially check the ever-increasing depletion of many 

 forms of marine animals whose economic value has long sustained 

 a many-sided fishing industry, any facts which may bear directly 

 or indirectly upon the life, habits or development of such forms 

 might seem to be of value. This is especially true of the Ameri- 

 ican lobster (Homams americanus), a knowledge of whose de- 

 velopment must influence not only methods of artificial propaga- 

 tion, which is in these days becoming more common, but also 

 state legislation in determining the size and season at which the 

 taking of lobsters shall be allowable. 



THE FREQUENCY OF MOLTING AND THE PERCENTAGE OF 



INCREASE. 



The r.ate of growth of a lobster depends primarily upon two 

 factors, the frequency of the molting periods and the amount of 

 increase in length at each molt. To date, the most complete and 

 only satisfactory account of the development of Homarus is pre- 

 sented by Herrick 2 who made many observations at Woods Hole 

 on all of the earlier and many of the later stages. Herrick found 

 that young lobsters (stages 2 to 10) in confinement gain from 1 1 

 to 15.84 per cent, at each molt, the average in 66 individuals 

 being 13.5 per cent. He assumes that 15.3 per cent, is the 

 average rate of increase both for the young lobsters which grow 

 up in natural environments, and for adults under normal con- 



1 This paper is presented with the purpose of giving in brief the main facts of a 

 more detailed report on this subject to the Rhode Island Fish Commission. The full 

 account will appear in The Thirty-Sixth Annual Report of the Rhode Island Com- 

 mission of Inland Fisheries, 1906. Reprinted as Special Paper No. 23, iqo6. 



2 HERRICK, U. S. F. C. Bulletin, vol. 15, 1895. 



233 



