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FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



capable of swimming rapidly. Sometimes, when 

 a group of lampreys is frightened, they scatter so 

 swiftly that a few may wriggle onto dry land to 

 points several feet from the shore. Also, when 

 rapids and swift currents are encountered, they 

 ascend quickly though not without considerable 

 effort. 



Table 22. — Rate of upstream movement of sea lampreys in 

 the 1951 spawning migration in Cayuga Inlet 



1 Not a true average rate of upstream movement because all specimens 

 were not always captured Immediately upon entering a station. 



1 Locations mentioned In this column are Identified on a map of Cayuga 

 Inlet (flg. 10, p. 679). 



Late migrants ascended the stream more 

 rapidly than did early migrants. The average 

 time for travel from the weir upstream 2.9 miles 

 to the U.S. Geological Survey dam was 11 days 

 (minimum, 2 days), during the period April 22-29. 

 Specimens that traveled the same section of 

 stream during May 10-15 averaged 4 days (mini- 

 mum of 1 day). Daily morning water tempera- 

 tures at the U.S. Geological Survey dam averaged 

 46° F. for the April 22-29 period and 59° F. for the 

 May 10-15 period. The stimulating effects of in- 

 creased water temperatures on the lamprey's 

 metabolic rate and spawning urge are believed the 

 cause of the faster rate of upstream movement 

 during the warmer period. 



Barriers to Upstream Migration 



Diurnal and nocturnal observations of the sea 

 lamprey's behavior throughout the 1951 spawning 

 migration indicated that a "partial-barrier" dam 

 is effective in retarding upstream movement and 

 serves as a block to some individuals. 



A small dam constructed for the U.S. Geological 

 Survey, Water Resources Division, across Cayuga 

 Inlet 5 miles upstream from the lake offered an 

 excellent place for observations of the lamprey's 

 reaction to a barrier. This dam consists of a con- 

 crete wall 30 feet long and 1 foot wide (fig. 11) with 

 an irregular concrete apron which extends 3 to 6 



feet downstream. A drop of approximately 1 foot 

 in water level is created by the dam, but the fall 

 varies inversely with the volume of waterflow. 



When early migrants first encountered this 

 small dam they reacted by searching actively back 

 and forth along the base for a bypass. After sev- 

 eral days of investigation, many proceeded down- 

 stream, and were observed as much as one-half 

 mile below the dam, slowly moving downstream, 

 seemingly in search of a tributary. 



To learn the fate of spawning-run sea lampreys 

 which were prevented from ascending a tributary 

 stream, Applegate and Smith (1951) captured and 

 tagged specimens that entered the Cheboygan 

 River in which upstream movement was blocked 

 by a power dam. Tag returns indicated that sea 

 lampreys will return to the lake from which they 

 came, and then search for another tributary. 



A tagging experiment on the Cayuga Lake sea 

 lamprey indicated a reaction similar to that found 

 by Applegate and Smith. Recovery of tagged 

 lampreys in Cayuga Inlet proves they will return 

 downstream at least 1 mile. In 1951, one of 59 

 tagged lampreys which were captured in Cayuga 

 Inlet and released in Fall Creek (fig. 10) was re- 

 captured in Cayuga Inlet. This lamprey had to 

 travel 1 mile downstream to Cayuga Lake, and 

 one-half mile in the lake to the mouth of Cayuga 

 Inlet. Of the 92 tagged lampreys released in Cas- 

 cadilla Creek, a tributary of Cayuga Inlet, 23 (25 

 percent) were later recaptured in Cayuga Inlet 

 proper. They had moved 1 mile downstream. 



Early arrivals in the spawning tributary attempt 

 to reach the headwaters, whereas late arrivals 

 occupy the lowermost reaches of the stream. Pos- 

 sibly the early arrivals, which are the larger, are 

 stronger and hence more able to progress up- 

 stream farther than late arrivals. Or, the greater 

 amount of time available to them may permit the 

 early migrants to travel farther. 



Waterflow also is a factor in upstream move- 

 ment. High waters in 1952 permitted lampreys 

 to cross the barriers and ascend to the very head- 

 waters of Cayuga Inlet; as a result the density of 

 nests was low throughout the stream. In 1951, 

 moderate waterflow made the barriers more effec- 

 tive. That year the density of nests was high in 

 the lower and middle section of the inlet and prac- 

 tically no nesting took place in the headwaters. 



With the passage of time the spawning urge 

 becomes increasingly strong. About mid-May, 



