198 
BULLETIN OF THE BUREAU OF FISHERIES 
evening of August 23. This fish was particularly conspicuous among the fish taken 
on the lock gate, constituting 90 per cent (by record) of all fishes taken that year. 
The accumulation of fish in the power-house inclosure and near by seemed to indi- 
cate that the fish, at least many of them, while seeking spawning grounds, move in a 
generally upstream direction and so at Keokuk are checked by the power house and 
dam. This seemed further evidenced by the fact that the fish seen in the inclosure 
and near the junction of the power house and dam were frequently jumping where the 
water fell, as where it leaked through stop logs. Some of the leaping fish cleared 
POUNDS 
the surface of the water by a distance estimated at 1 % meters (5 feet). However, the 
demands of breeding could not account for the presence of fish after the middle of 
July, when they were generally present in somewhat reduced numbers. 
The most striking accumulation of fish near Keokuk after the spring of 1914 
(river herring, p. 167) was shown by carp near the lock in the middle of July, 1916. 
Mr. Huele, the lock master, stated that the aggregation of carp began July 16. 
Observations by Stringham were first made on the 17th from 2 to 5 p. m. The fish 
were gathered about the bottom of the chute for driftwood, situated between the lock 
and the lower end of the power-house structure. The number of fish in view at any 
given moment in this small area was variously estimated by several observers at 
from 4,000 to 50,000. Such estimates are significant only as indicating that the fish 
were seen in extraordinary numbers. 
