REPORT OF COMMISSIONER OF FISH AND FISHERIES. 79 



for their capture. This required a knowledge of the distribution of the 

 several species, of their habits and movements, their food, their spawn- 

 ing seasons and places, and of the history of the younger stages. With 

 respect to the api)aratns, it was essential to ascertain the character, 

 location, and amount of each kind in use and the conditions under which 

 their operation is efi'ective. The position and extent of all fixed appli- 

 ances were accurately determined and represented on a series of charts 

 to illustrate graphically their relations at different periods to the bodies 

 of fishes which they intercept, and the distribution by quantity of the 

 movable appliances, the gill nets especially, was worked out, for each 

 season, with as much deflniteness as possilde. The sizes at which the 

 different fishes reach maturity in relation to the sizes of the mesh in 

 the several kinds of nets by which they are taken, and the extent of 

 capture of immature sizes were also studied, as well as the effects of 

 fishing during the spawning seasons and at other periods when harmful 

 results are claimed to be produced, the effects of polluting agencies, etc. 



The relations of the size of mesh in the pound nets to the sizes of the 

 fishes taken by that means was, moreover, made the subject of experi- 

 ment both in the fall of 1894 and in the spring of 1895, a i)ound net 

 specially constructed with a different size of mesh on each side being 

 employed for that purpose. During the former period it was fished off 

 Huron, Ohio, in one of the pound-net strings owned by Messrs. 

 Wickham & Co., and during the latter period off the south side of 

 Kelley Island in one of the strings belonging to the Sandusky Fish 

 Company. The net was operated free of charge by both of these firms, 

 and every means was taken by them to insure it a fair trial. Mr. Eut- 

 ter was in charge during the fall season and Mr. Hardin during the 

 spring. 



The mackerel inquiries conducted in part with reference to the 

 requirements of the joint investigation were continued during the sum- 

 mer of 1894 and were again taken up in the spring of 1895, as explained 

 under another head. During May, 1895, the representatives visited the 

 southwestern coast of Nova Scotia for the purpose of investigating the 

 movements and other points in the natural history of the mackerel, as 

 well as the fisheries to which they give rise in that region, no previous 

 observations having been made with respect to that subject there. 



During July and August, 1894, a detailed hydrographic survey of 

 the upper tidal part of the St. Croix Eiver, lying between the State 

 of Maine and the Province of Xew Brunswick, was made by Ensign 

 W. L. Dodd, U. S. iT., executive officer of the steamer Fish SawJc, 

 assisted by H. A. Eoss and W. F. White, of Bowdoin College. The 

 object of this work was to provide the necessary data for determining 

 the extent to whicli the sawmill refuse from the mills above have affected 

 the river channel since the previous Government surveys, and its con- 

 sequent influence upon navigation and upon the salmon and other 

 anadromous fishes which resort to those waters. 



