REPORT OF COMMISSIONER OF FISH AND FISHERIES. 91 



all former experiments it bad been impossible to discover any food 

 suited to tbe larval oysters, or any means of renewing tbe water with- 

 out losing the latter, owing to their small size, and they soon ceased to 

 grow, dying of starvation. Mr. Sigerfoos was successful in devising a 

 partially satisfactory method for replenishing the water and in finding 

 that the young will feed voraciously upon a certain kind of alga after 

 it has been finely powdered in a mortar. Under this treatment they 

 grew rapidly for some time and large quantities were carried in good 

 health past the stage where the former experiments met with failure, 

 but after a while the remains of the powdered algae, which were so 

 minute that no way of getting rid of them could be found, caused the 

 water to become vitiated with the inevitable result of destroying the 

 larvae. It is intended to continue these studies at a future time. A 

 good series of tbe young attached oysters of all stages from one hour 

 up to maturity were obtained and preserved for examination. 



Mr. Sigerfoos also began upon a study of the shipworm (which is 

 quite abundant in this region) from both a scientific and practical 

 standpoint, securing material for a complete life-history of three species. 

 It is expected that important results will be obtained, suggestive of 

 more effective methods of protecting submerged timber against its 

 inroads than are now recognized. A full report upon the subject is in 

 course of preparation; a short preliminary paper on the development 

 of the several forms observed has been published. 1 



INQUIRIES RESPECTING THE MACKEREL, MENHADEN, ETC. 



MACKEREL. 



The investigations respecting the habits and abundance of the mack- 

 erel and the- fisheries to which this important species gives rise were 

 continued again this year upon the same general plan as in 1893, but 

 on a more elaborate scale and during a greater part of the season. 

 The schooner Grampus and steamer Fish Hawk were both utilized in 

 connection with this inquiry, and several land parties were employed 

 to study the subject from the standpoint of the inshore fisheries along 

 the entire coast covered by the range of the species. The information 

 sought to be obtained from this series of observations was desired for 

 the use of the Joint International Commission, as elsewhere explained, 

 and the practical importance to the American tishermen of reaching 

 a more complete and definite understanding of all the circumstances 

 connected with the natural history of the mackerel, in relation to the 

 several methods employed for their capture, has long been acknowledged. 



Until this work was started by the Fish Commission a few years ago, 

 most of the facts at hand were such as had been obtained incidentally, 

 and it is only within a year or two that the matter has been taken hold 

 of in the systematic and comprehensive manner which it deserves. The 



■The PholadidaB; note on the early stages of development. By ('. P. Sigerfoos, 

 Johns Hopkins University Circulars, xi\ ', Xo. 119, June, 1895, pp. 78, 79. 



