612 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE. 



Table 49. — Location of sea lamprey attachments on lake 

 trout 



[The areas of attachment are indicated in fig. 25] 



yielded a value corresponding to p = 0.008). Two 

 explanations may be offered for this disparity. 

 First, the superimposition of lamprey attachment 

 over a previously existing scar would obliterate 

 the original scar. Secondly, the mortality may 

 be higher from wounds in the head and pectoral 

 region than from wounds in other sections of the 

 body. 



Sea Lamprey Parasitism on the White Sucker 



Information on the incidence of sea lamprey 

 attacks on white suckers was obtained by the 

 examination of spawning-run fish collected by 

 means of an electric shocker from Butternut 

 Creek, a tributary of Cayuga Inlet, on May 3, 

 1951, and May 6, 1952. Most of these suckers 

 are believed to have been lake-dwelling fish that 

 had ascended the stream to spawn. Possibly some 

 stream -resident suckers were included. 



The data on attacks on white suckers give no 

 indication of difference between 1951 and 1952. 

 White suckers less than 11 inches long bore no 

 scars or wounds in either 1951 (15 fish) or 1952 

 (22 fish). At the greater lengths the percentage 

 of scarred or wounded fish tended to increase 

 with increase in size, as is brought out clearly 

 by the following comparison of incidence of attacks 

 in suckers 11.0-13.9 inches long and in fish 14 

 inches long or longer. 



same as that observed by Hall and Elliott (1954) 

 in Lake Huron. 



The cause for the increase in the incidence of sea 

 lamprey attacks with increase in the size of white 

 suckers is not known. Possibly the smaller fish 

 are less able than larger ones to survive attack. 

 Again, mechanical difficulties of attachment may 

 give the smaller suckers a degree of immunity 

 from lamprey predation. 



PARASITES AND PREDATORS OF THE 

 LAMPREY 



Parasites 



In the one previously published report on para- 

 sites of the sea lamprey in the Finger Lakes area, 

 Van Cleave and Mueller (1934), who examined 12 

 sea lampreys from Oneida Lake, found trematode 

 larvae. In more extensive studies, on mature sea 

 lampreys from the Ocqueoc River and Carp 

 Creek, tributaries of Lake Huron, Applegate 

 (1950) and McLain (1952) reported parasitization 

 to be rather low, generally less than 20 percent. 

 Most common internal parasites were acantho- 

 cephalans of the genus Echinorhynchus, cestodes 

 (Triaenophorus) , and nematodes (Cammallanus) . 

 Externally, the leech Pisicola milneri was occa- 

 sionally present. 



The examination of 25 sexually mature sea lam- 

 preys from Cayuga Inlet during 1951 and of 53 in 

 1952 disclosed only one internal parasite, a small 

 (1.5 mm.) acanthocephalan of the family Neoech- 

 inorhynchidae in the intestinal tract of a medium- 

 sized female from the 1952 collection. 



No external parasites were evident at any time 

 during the 1950 spawning migration, but an epi- 

 demic of leeches occurred during the 1951 and 1952 

 migrations. The leech, Pisicola zebra Moore, 11 

 is approximately M-inch long and Ke-inch wide. 

 These leeches usually adhered in clusters to the 

 dorsal and posterior edges of the first and 

 second dorsal fins and the tip of the caudal fin. 

 The leeches reached a peak of abundance on May 

 14, 1951, when they were present on 93 percent 

 of the lampreys. At this time it was estimated 

 that most of the infested lampreys carried approxi- 

 mately 50 to 300 leeches. The only visible dam- 

 age to the lamprey was a slight erosion of the fin 

 margins where the leeches had been attached. 



This trend toward a greater incidence of sea lam- 

 prey attacks among the larger white suckers is the 



i Identified by Dr. Marvin C. Meyer, University of Maine. 



