522 



washed fishes out into the river, where they became sick from sew- 

 age and could be picked up easily with a dip-net. The following 

 morning a 3-pound carp, 2 horned dace (Semotilus atromaculatus), 

 and an orange-spotted sunfish were obtained in this way. Several 

 hauls with small seines were made October 4, but no fish were caught 

 except a few bullhead minnows at the mouth of one of the creeks. 



Below the Dam. — Turning now to the situation below the dam 

 at Marseilles, we find that in July and August, 191 1, the ratios of 

 dissolved oxygen three fourths of a mile below were more than three 

 times as great as those just above* ; that under winter conditions 

 in February and March they were 13 and 14 per cent, greater; and 

 that in August and September, 191 2, with cooler weather and higher 

 river levels than in the previous year, they varied from one and a 

 half to two times as great. The necessity of taking samples for 

 analysis at some distance below the fall was shown by the fact that 

 the oxygen content of the water September i, 191 1, an eighth of a 

 mile below, was more than ten times that above — a discrepancy to 

 be accounted for only on the supposition that the air mechanically 

 caught in the water at the fall had not yet had time to escape. The 

 water below the fall in 191 1 was visibly cleaner than that above, and 

 there was less Spharotilus iiataus in the plankton collections. This 

 was probably due in part to sedimentation in the slack water above 

 the dam, and in part to the pulverization of the coarser organic parti- 

 cles by the pounding of the water at the fall. 



We were told by observant residents, in 191 1, that fishes usually 

 come up to Marseilles in some variety — bass only in the highest water, 

 but carp in both summer and winter of every year; but none of 

 either were seen or heard of there in July and August of that year. 

 Strings of black bullheads w^ere being caught below the dam Octo- 

 ber 13, 191 1, and carp were said to have been common there since 

 the fall rains began. Our winter fishing wath set-nets and dynamite 

 was, however, no more productive than at Morris. Small nets set 

 in February, 191 2, from one hundred to two hundred yards below 

 the dam, near the north shore, caught only two shiners, and were 

 then destroyed by floating ice; and six sticks of dynamite, exploded 

 from a half to three quarters of a mile below the dam, gave us only 

 two more of the same species. The stomachs of all these fishes 

 were empty. 



August 14 and 15, 19 12, we found essentially the same conditions 

 as to fishes below^ the dam w^hich were found above, except that we 



*It was impossible to reach the center of the stream here, and samples were 

 taken from the stern of a skiff fifteen feet from the north shore, in water two 

 feet deep. The current at low water, Jul\- 31, was estimated at five miles per hour. 



