The Lake and Brook Lampreys of New York 461 



grounds that year deposited 65,000 ova there would have 

 been laid 65000X400=26,000,000. Many of the ova fail of 

 fertilization and many also fail to develop even if fertilized so 

 that of the possible twenty-six million young lampreys from 

 the spawn of a season, possibly not over 4 or 5 thousand 

 reach the sand beds ; and from the further decimation of these 

 the numbers in the lake remain approximately uniform as 

 with other animals in nature. 



Ridding the Lakes of Lampreys. — From the foregoing ac- 

 count of the life history of the lamprej' it will be seen that it 

 has a single very weak point, viz., leaving the lake and 

 running up the tributaries to spawn. This seems to be the 

 only weak point at which the lamprey can be attacked with a 

 hope of exterminating it. This point is rendered still weaker 

 from the fact that in Cayuga Lake, and in Seneca Lake, so far 

 as explored, the lampreys run up the inlet at the head of the 

 lake only, and do not spawn in the tributaries entering the 

 lake at intervals on each side. Some of the lateral tributaries 

 seem well adapted for the lamprey's spawning grounds ; these 

 streams are used by other fishes, but the most careful ex- 

 ploration under favorable circumstances gave no sign of the 

 lampreys. Also, as will be seen by examining the map (PI. 

 II), the large creek (Fall Creek) entering the head of Cayuga 

 Lake by a separate entrance, has never been known to con- 

 tain lampreys. Careful personal search was made for several 

 seasons and inquiry made of those familiar with the creek, 

 but none were ever found or heard of. This may be due to 

 the nearness of the falls in the course of the stream. The 

 creeks joining the inlet (Cascadilla and Six Mile creek.s) con- 

 tain them. Formerly they were very abundant in both, but 

 the water is not now so plentiful and then both extend for a 

 considerable distance through the city. At present it is the 

 main stream that is most frequented and employed by the 

 lampreys for spawning. The lampreys must be destroyed 

 before spawning if they are to be exterminated. Nothing 

 would be easier than to do this. A dam with a fish-way, the 

 fish-way leading into an isolated enclosure where the 

 lampreys could be easily removed and disposed of, or a weir 



