110 
BULLETIN OF THE BUREAU OF FISHERIES 
seines at Lake Pepin but none with the snouts broken. On October 1, 1916, Franz 
Schrader wrote that he examined about 40 captured by seine at Lake Pepin that 
year. About half of these were examined closely for microscopic parasites; some had 
slight abrasions, but none had any serious injuries. Stockard (1907) evidently 
examined many fish during two springs in Louisiana, but the number is not indicated ; 
he found three whose snouts had been broken and the wound healed over. 
It will be noted that the injuries received about Keokuk were almost exclusively 
to the heads of the fishes. To secure testimony as to the part of the body that was 
usually hurt, the question was put to a number of fishermen and dealers, care being 
taken to make it general in form so as not to indicate the answer expected. The 
dates of inquiry, names of men, residences, and the substance of the replies are as 
follows : 
August 29, 1916 
Ed. McGee, West Keokuk. Spoonbill (paddlefish) injured only on snout; buffalofish some- 
times have scales off and are sometimes hurt on mouth. 
September 4, 1916 
Joe McAdams, Keokuk. Generally on head or behind shoulder girdle; hardly ever elsewhere. 
William Stanton and Mr. Wilson, Keokuk. Mostly on head, but occasionally a hole is punched 
in them anywhere. 
Trumer Jackson, Warsaw. Spoonbill and carp, mostly on head, some nearly cut in two. 
No injury to any other part noticed. 
Luthur McAdams, Alexandria. On head only. 
September 15, 1916 
Jack Job, Canton. Mostly on head, sometimes on tail. 
Joseph Winkler, Canton. No injured fish found. 
STRUCTURES CONSIDERED 
The rock piles at the base of the dam and the turbines are the two instrumen- 
talities that had been suspected of being responsible for injuries to fish. The rock 
piles have been mentioned in connection with the description of the dam on page 
93. (See, also, fig. 12.) During the spring of 1915 the power company was making 
some observations on the turbines, and this gave an opportunity to inspect the 
structures in question; the descent to the turbine was made on April 1. If a fish 
should get to the head bay and through the screens or grating as already suggested 
(p. 97), it would then be in the intake or scroll chamber; this is normally full of water 
even when not in operation. As shown in Figure 13 it is dry. The flow of water 
is regulated by opening or closing the gates or vanes, which appear in the upper 
middle of the illustration behind slender columns; they open and close by partially 
revolving on their long axes. These vanes are the first obstacle that a fish would 
meet after passing the screens. On the day of observation the vanes stood with 
openings between them about 9 inches (23 centimeters) wide. When a unit is gener- 
ating electricity these are slightly but constantly oscillating, so as to regulate pre- 
cisely the pressure on the turbine; but the size of the opening remains substantially 
the same as when it was measured, except that one unit, used for electricity sold 
locally, has a smaller opening, being, about 5 inches wide, according to information 
supplied by the power company. 
Inside the vanes is the turbine, more commonly called “wheel.” Between the 
vanes and the blades or buckets of the wheel there is a large space. The wheels are 
