SEA LAMPREY OF CAYUGA LAKE 



581 



lower population limits were determined to be 



9,897 and 8,972. 



1952 



The number of upstream-migrant lampreys that 

 entered Cayuga Inlet in 1952 was estimated to be 

 4,435. This estimate is based on 1,773 marked 

 specimens and a total catch of 3,413. A total of 

 1 ,234 marked specimens were recaptured. 



Table 19. — Estimate of the number of sea lampreys in the 

 1951 spawning migration in Cayuga Inlet 



1 Values computed from data in table 18 and the formula given on p. 580. 



All lampreys utilized for this population estimate 

 were captured at the U.S. Geological Survey dam 

 or at Newfield station during April 30 to June 3. 

 They were caught by a portable lamprey trap and 

 by hand. The lampreys were marked by a sys- 

 tem of notches made in the dorsal and caudal fins, 

 and were all released at the U.S. Geological Survey 

 dam. They were subsequently recaptured at the 

 dam or upstream at Newfield station. Dates and 

 numbers of lampreys marked and captured are 

 included in table 20. 



The Schaefer method was again used to estimate 

 the number of lampreys. Weekly summaries of 

 tagging and recapture are listed in table 20. In 



table 21 are the population estimates recorded by 

 weekly periods. The number of lampreys in the 

 1952 spawning run was calculated to be 4,435, 

 with 95-percent fiducial limits of 4,108 and 4,818. 

 These population estimates for the 1951 and 

 1952 seasons are considered to be reliable. All 

 theoretical assumptions are believed to have been 

 adequately fulfilled. 



Table 21. — Estimate of the number of sea lampreys in the 

 1952 spawning migration in Cayuga Inlet 



' Values computed from data in table 20 and the formula given on p. 580. 

 Rate of Upstream Movement 



The tagging and recapture of many lampreys at 

 six locations along Cayuga Inlet during the spring 

 of 1951 provided an opportunity to measure the 

 rate at which they proceed upstream on their 

 spawning migration (table 22) . 



Sea lampreys traversed the slow-moving por- 

 tions of Cayuga Inlet at a rate of 1 to 2 miles per 

 day. Farther upstream where the current is 

 swifter, their rate of travel decreased to approxi- 

 mately one-third to 1 mile per day. Actual 

 swimming velocity under average conditions 

 approximates 1 foot per second, but frequent "rest 

 periods" account for a large share of their time. 



When the occasion demands, the lamprey is 



