SEA LAMPREY OF CAYUGA LAKE 



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1949 



1950 



1951 



10 12 14 16 18 20 22 24 26 28 30 

 FORK LENGTH IN INCHES 



Figure 23. — Mean number of sea lamprey wounds on lake trout 8 to 30 inches in length during 1949, 1950, and 1951. 



Table 45. — Incidence of sea lamprey attacks on lake trout 

 and sea lamprey abundance in Cayuga Lake, 1949-51 



erably in both the percentage of trout wounded 

 and in the mean number of wounds per fish. Cay- 

 uga Inlet, the only significant source of lampreys, 

 enters the southern end of the lake, Section I (fig. 

 24 shows boundaries of the five sampling sections). 

 This section extends northward 7 miles. Section 

 II, a relatively small area off Flat Rock and 

 Taughannock and Frontenac Points, is the major 

 spawning ground for lake trout in Cayuga Lake. 

 Across the lake and somewhat northward another 

 small area, section IV, extending from Kings 

 Ferry north to Willets, is a summer concentration 

 area. Section III is the deep, middle portion of 



the lake. Section V is the northern, relatively 

 shallow end of the lake. 



Trout from section II and IV exhibited a high 

 incidence of lamprey wounds, whereas those from 

 sections I, III, and V showed a lower degree of 

 parasitism (table 46). The unweighted mean 

 numbers of lamprey wounds per trout in sections 

 II and IV were 0.83 and 0.85, respectively. In 

 Sections I, III, and V the mean values were 0.38, 

 0.44, and 0.44. The percentage of trout bearing 

 wounds produced a similar picture. In sections II 

 and IV the unweighted mean percentages of 

 wounded trout were 44 and 54, respectively. Sec- 

 tions I, III, and V had mean percentages ranging 

 between 26 and 38. Chi-square tests of inde- 

 pendence indicated that differences in the inci- 

 dence of parasitism among the 5 sections are sig- 

 nificant. Section IV, the principal summer habi- 

 tat of lake trout, ranked highest both in percent- 

 age of wounded fish and in number of wounds. 



Seasonal trends in feeding activity of sea lampreys 



Changes in feeding activity with time of year 

 may be judged from monthly records of incidence 



