3<H 



BULLETIN OP THE BUREAU OF FISHERIES. 



which were punched in the uropods of large individuals under observation remained open 

 after the shell was cast. Such holes, however, were observed to close in a few young 

 individuals. 



RATE OF GROWTH AND SIZE. 



The rate of growth depends upon the frequency of molting, and consequently varies 

 with age, abundance of food, and temperature of the water. The young increase in 

 length more rapidly than the adults because they molt more frequently. The actual 

 increase at each molt was found, however, to be small. This increase was not noticeable 

 immediately after molting, but when measurements were made three or four days later 

 it was observed that the percentage of increase in the length of the carapace of females 

 averaged 3.32 and of males 2.75. The ratio of the increase in length of the young at 

 each molt is about the same as that of the adult. The actual increase in length of the 

 adult at each molt is, of course, greater than that of the young, because the percentage 

 of increment at each molt is based upon the length of a larger individual. For example, 

 the actual increase at molting in the case of a male spiny lobster 2 inches long would be 

 0.055 inch, while that of one 5 inches in length would be 0.1275 inch. 



The most rapid increase in weight at each molt occurs in the young, the percentage 

 of increase in weight at each successive molt becoming smaller. Table 2 shows the gen- 

 eral relationship between the length and weight of spiny lobsters of various sizes. 



Persistent fishing apparently has reduced the size of spiny lobsters near Key West, 

 but very large individuals are found around the Dry Tortugas and parts of Florida 

 Reefs unfrequented by the fishermen. Measurements of a few of the largest spiny lob- 

 sters brought into the Key West market indicate that the maximum size of those caught 

 near Key West is 14 inches total length, excluding the antennae, with a weight of about 

 5 pounds. Several very large males brought from the Dry Tortugas measured 18 inches 

 in total length, excluding the antennae, and weighed from 6 to 8 pounds. No females of 

 this size have been observed, the largest measured being not over 13 inches in total 

 length. 



The weight increases rapidly with increase in length, but individuals vary greatly in 

 weight because of the loss of appendages and differences in the proportions of the body. 

 The pleon of the female is wider than the pleon of the male, and females weigh more than 

 males of the same length. 4 



Table 2 is compiled from the measurements and weights of over 150 individuals. 

 It is a comparison of the lengths and weights of the sizes of spiny lobsters usually brought 

 into the market at Key West. 



Table 2. — Comparison of Lengths and Weights of Sizes of Spiny Lobsters Brought to Key 



West (Fla.) Market. 



Length carapace (inches). 



2. 0-2. 4 

 a. 5-2. 9 

 3-0-3-4 

 3.5-3.9- 



Average 



total 



length 



(inches). 



5-5 



6.875 



8.2s 



9-375 



Average weight. 



Pounds. Grams, 



0. 26 

 ■54 

 • 87 



1. 29 



120 

 245 

 395 

 58S 



Length carapace (inches). 



4- o-4- 4 

 4- 5-4. 9 

 4.9-S. o 



Average 



total 

 length 

 (inches). 



10. 50 

 11.50 

 12.50 



Average weight. 



Pounds. Grams 



1.8s 

 »-5i 

 3-42 



840 

 1,140 

 1.550 



