560 REPORT OF THE COMMISSIONER OF FISHERIES. 
REACTION OF CARP IN PONDS TO INFLOWING FRESH WATER. 
This reaction, which is very curious and marked, I am uncertain 
whether to consider a reaction to the current caused by the inflowing 
water or aresponse to the volume of fresh water being added to that 
which has been standing in the pond. Hessel (1881, p. 879) says: 
The inflow of water into the pond should never be allowed to be direct; as, for 
instance, a brook falling into it. This often causes the water to rise at an iInoppor- 
tune time, carrying into the pond other fishes, especially the rapacious pike. The 
carp also has the disposition to swim toward the inflowing water, by which means it is drawn 
away from tts proper feeding-places. & 
This matter. was first brought to my attention in a practical way by 
Mr. Thomas Hurrell, who owns a carp pond near Port Clinton, Ohio. 
This pond covers an area of some 20 acres, or, more, of marsh land 
beside the Portage River. A deep cut was made along the riverside 
and embankments thrown up on three sides so that it 1s possible to 
keep the water level two or three feet above that of the river, the 
fourth side of the pond being formed by the natural slope of the land. 
The water is maintained at a nearly constant level by pumping in fresh 
water, as necessary, from a dredge-cut just outside the embankment 
which leads from the river. The water is really elevated by means of 
an endless-chain elevator. This is shown in figure 2, plate 11, while 
figure 1, plate 111, shows the chute which empties into the pond. At this 
place the water in the pond is some 8 to 10 feet deep, and directly 
from it leads the deep ditch along the riverside, while shallower ditches 
lead off into other parts of the pond. (See figure, p. 628.) Mr. Hur- 
rell said that scarcely has he started the elevator when the fish begin 
to come from all parts of the pond and to congregate in the deep area 
where the fresh water pours in. His account of their quick response 
seemed almost incredible, and I expressed a desire to see the thing 
myself; at which Mr. Hurrell kindly started the gasoline engine oper- 
ating the elevator, and at once a good stream of fresh water began to 
be poured into the pond. I was subsequently fortunate enough to 
witness the phenomena I am about to describe on several different 
occasions. The following account is taken with little change from my 
notes of one time: 
At the time of which I am speaking, a number of carp could be seen 
swimming about in the vicinity of the pumping house with their backs 
out of water. Mr. Hurrell attributed this to the fact that he had 
recently been pumping, and that the fish had not all dispersed as yet. 
He now started the engine again, and within five minutes the carp began 
to congregate in numbers in that vicinity, and they could be seen com- 
ing far down the large ditch, as many of them swam with their dorsal 
fins above the surface. The water near the infiow was soon full of 
them—it seemed as if there must be a number of tons of fish right 
aThe italics are mine, 
