460 Simon Henry Gage 



side so that the lamprey's head and branchial apparatus are 

 out of water. By this means the lamprey is partly suffocated 

 and lets go its hold, thus freeing the fish. 



That the injury to the food fishes is very great may be in- 

 ferred from the fact that sometimes out of 15 cat fish caught 

 on a set line in one night, 10-12 have great raw sores where a 

 lamprey has attacked them. In the spring, too, when the 

 suckers {Catostomtis) run up to spav/n, very many of them 

 carry a lamprey, and naturally by the great drain of blood 

 that it causes, the fish must be weakened, so that obstacles on 

 the way to the spawning ground are less liable to be sur- 

 mounted than as if the fish were in full vigor. 



As stated above, during a single season over a thousand 

 lampreys were caught in the Cayuga Lake inlet. If these 

 had spent from two to three years infesting the fishes of the 

 lake they probably did more to reduce the number of avail- 

 able food fishes than the fishermen. 



In 1 89 1, on account of the lack of rain and the clearness of 

 the water in the streams at the spawning time, conditions 

 were very favorable for determining the number of nests in the 

 Cayuga Lake inlet. This was done for about 10 kilometers, 

 and 400 ne.sts found. If each nest had been inhabited by 

 a single pair, then 800 lampreys visited the inlet for spawing 

 during that spring; but in 18S6 over 1000 were known to 

 have been caught from the inlet, and furthermore by direct 

 observation some of the nests are utilized by at least two 

 pairs of lampreys, so that probably the 400 nests represented 

 a visit of 1000 to 1200 lampreys and perhaps more. The 

 males are usually somewhat in excess so that probably there 

 were from four to six hundred females. The number of eggs 

 in the ovary of a lamprey of moderate size was estimated in 

 the usual way by weighing a small piece and counting the eggs 

 in it and then weighing the whole ovary. The eggs 

 present in the whole ovary is then estimated by a simple 

 proportion. In the case mentioned, the ovary was found to 

 contain 65,000 ova. (A sea lamprey from the Merrimac 

 River was found, by the same method, to contain 236,000 

 ova). If each of the females that were on the spawning 



