REPORT OF COMMISSIONERS OF INLAND FISHERIES. 



173 



VI. Observations on the Rate of Growth of Lobsters 

 Past the Tenth Stage. 



Before we turn to consider how these foregoing observations bear 

 upon the probable normal rate of growth of the lobster, it may be 

 well to examine data (Tables Nos. 9 and 10) compiled by Dr. A. D. 

 Mead and Dr. L. W. Williams on the rate of growth of certain groups 

 of lobsters in captivity at the Wickford Station of the Rhode Island 

 Commission of Inland Fisheries.* From these observations we can 

 gather many valuable points which serve to guide us in the estimation 

 of the rate of growth of adolescent lobsters. 



We find that, of 149 young lobsters hatched between June 1 and 

 June 26, the average length on September 15 was 31.8 mm., the ex- 

 tremes being 44 mm. (hatched June 1) and 20 mm. (hatched June 26). 

 Of these 149, about 10 months after hatching, 23 individuals gave 

 an average length of 50 mm. while June 12, approximately one year 

 after hatching, 79 gave an average length of 53.5 mm. A full list 

 of the one-year-old lobsters examined stands as follows : 



*From time to time there have been attempts made at the Wickford Hatchery to raise 

 lobsters to sexual maturity. These attempts have not been successful owing to the hard win- 

 ters, the ice-packed harbor, and some insufficiencies in the construction or placing of the lob- 

 ster cars for winter months. The attempt made by the writer during the winter of 1905-6 to 

 'keep lobsters in earthenware jars filled with salt water was a failure, owing either to poison- 

 ing from the jars or to unevenness in water temperature. The water may be cooled to such 

 an extent that it freezes at the surface and no harm is done, but rapid changes appear to 

 cau.se disastrous results. That lobsters kept in a cold and constant temperature require but 

 a small amount of water, with infrequent changes, is shown by the fact that a few young lob- 

 sters which the writer entrusted for the winter to Mr. E. W. Barnes, and which he kept in a 

 cold room in bottles, (whose width was scarcely greater than the length of the lobsters), passed 

 the winter in safety. Of over fifty kept in this way but two died. The others were in good 

 condition when again placed in their comi)artment cars in Wickford Cove about April 1, 1906. 



