614 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



spawning stream above the dam. It is estimated 

 that about 75 percent of the entire spawning run 

 could be captured. A trap suitable for this pur- 

 pose would cost less than $50 and would require 

 less than 50 man-hours annually for maintenance 

 and operation. 



SUMMARY 



The recent invasion of the upper Great Lakes 

 by the sea lamprey, and its depredation on the 

 food and game fish have necessitated an investiga- 

 tion to discover methods of controlling this para- 

 site. One aspect of the program was the present 

 study of a long-established population of the land- 

 locked sea lamprey. 



Geological formation of the Great Lakes and 

 the Finger Lakes of New York State, and the 

 present distribution of the sea lamprey, lead to 

 the conclusion that the lamprey entered Cayuga 

 Lake by way of the "Champlain Sea" or the 

 Hudson-Champlain estuary and Mohawk outlet 

 during the latter part of the Pleistocene period. 



Fieldwork was conducted from May 1950 to 

 August 1952. Mature lampreys were captured 

 in Cayuga Inlet by a weir, portable traps, and by 

 hand. In all, 9,480 adult lampreys were captured. 

 Of this number, 1,168 were tagged and 1,773 were 

 fin-clipped and released in Cayuga Lake tribu- 

 taries. Lake trout were taken by gill nets from 

 Cayuga and Seneca Lakes. Immature, parasitic- 

 phase lampreys were collected by removal of those 

 adhering to lake trout taken in gill nets. Digging, 

 seining, and electric shocking were employed for 

 collecting larval lampreys in Cayuga Inlet. 



In 1950, 1951, and 1952 the mean total lengths 

 of adult, upstream-migrant lampreys were 15.0, 

 15.3, and 15.9 inches, respectively. The annual 

 differences in length were significant, but the dif- 

 ferences in length between males and females were 

 not. Mean weights of upstream-migrant sea lam- 

 preys for 1950, 1951, and 1952 were 4.97, 4.34, and 

 4.94 ounces, respectively. In 1951, Cayuga Lake 

 sea lampreys were approximately the same size as 

 those taken in Carp Creek, a tributary of Lake 

 Huron. This same year the largest landlocked 

 sea lampreys were taken in Seneca Lake, N.Y. 

 Mean length and weight of parasitic-phase sea 

 lampreys captured in Cayuga Lake in September 

 and October were 13.7 inches and 3.8 ounces. 

 Mean length and weight of Seneca Lake sea lam- 



preys captured during the same months were 15.5 

 inches and 5.3 ounces. 



Transformation from the ammocoete to the 

 adult stage began in August and terminated in 

 March. Parasitic feeding began in March and 

 continued approximately 14 months. During the 

 early transformation stage the sea lamprey de- 

 creased approximately one-half inch in length. 

 For the following 6 or 7 months, while buried in 

 the stream bottom and in a nonfeeding phase of 

 life, they increased approximately one-fourth inch 

 in length and at the same time lost about 0.02 

 ounce in weight. After emerging from the bot- 

 tom and starting their parasitic phase of life in 

 the lake, they increased in length from 5.5 inches 

 in March to 15.4 inches in April-May of the fol- 

 lowing year. Length-frequency distributions of 

 specimens from both Cayuga and Seneca Lakes 

 prove that lampreys spend only 1 full year in the 

 lake. Essentially only one age group is present 

 in the lake at any one time. 



The length-weight relation was determined 

 from 1,906 adult lampreys captured in Cayuga 

 Inlet during April and May 1951. 



Body proportions changed with the attainment 

 of maturity. These proportions differed signifi- 

 cantly between sexes at one time or another be- 

 tween September-October and the following June, 

 and a majority of these proportions differed most 

 at spawning time. Teeth, tooth-cusp, and myo- 

 mere counts of Cayuga Lake specimens and 

 Seneca Lake specimens reveal a divergence of the 

 two populations at a racial level. 



Of eight tributaries available to the lamprey for 

 spawning, Cayuga Inlet was the only one used to 

 any appreciable extent. The sea lampreys usually 

 enter Cayuga Inlet during the last 2 weeks of 

 April. Sea lampreys that arrived in the tribu- 

 taries for spawning in mid-April spent 4-5 weeks 

 in the stream before initiating nest construction. 

 Activity of lampreys on the spawning migration 

 was closely associated with water temperature. 



Estimates of the number of lampreys in the 

 spawning migration were: 1950, 10,000-15,000; 

 1951, 9,390; 1952, 4,435. Estimates were based 

 on marking and recapture. 



The rate of upstream travel was about 1 to 2 

 miles per day in the slow-moving portions of 

 Cayuga Inlet. In the swifter, upstream area the 

 rate of travel decreased to approximately one- 



