Ihijring the period April 15-April 19, repeated trips vrere made 

 to the c^avel "fan" at all times of the day and night by the \vi-'iter, 

 Mr. Robert Frank (formerly yrLth the Fish Division, Department of 

 Conserv^ation), and llr. Edv/ard Karsten of Ocqueoc, Uichigan, On 

 April 1^, about 11:00 P. 11., a male sea lamprey 19o3 inches long 

 and a female 16,7 inches long rrere seen and captured by spearing. 

 Three others were seen later in the night. On the follomng night, 

 about midnight, tivo females, 1^.3 and 17o2 inches long, T'ere like- 

 ■wise taken. Again, at least tiro more were seen in the follovdjig 

 hours. On both nights, the vfater temperature remained at 1|0 degrees 

 F, during the hours of observation — the air temperature varied from 

 2k degrees F, to 32 degrees F, A total of six sea lampreys were 

 observed imder similar circumstances on the succeeding three nights. 



From these observations, made at all hours of the day and 

 night during this period, \m gained the impression that the sea 

 lampreys observed were mailing no effort to enter the Carp Creek 

 proper at that time. None were ever observed during the daylight 

 hours. About two hours after full darkness they seemed to appear 

 suddenly on the central and outvrard portions of the "fan" vjhere they 

 apparently remained until dawn. They were never in evidence in the 

 estuary or lovrer creek proper at the times inspections were made on 

 the "fan". I presume from this that they dropped back into the bay 

 vdth the coming of daylight. 



Unfortunately, we cannot fix the exact date when the actual up- 

 stream migration began. The weir and trap were put in operation on 

 April 21 and by the follovrijig morning (April 22) one specimen had 

 entered the trap. During the period April 15~18, water in the creek 

 proper was one degree or more colder than that in the bay. This ira,s 

 due primarily to melting snovr run-off in the watershed. On April 19, 

 20, and 21 the temperature of the water rose above that of the bay 

 for a few hours each afternoon, I believe that these temperature 

 differences between the creek and the bay were responsible for the 

 behavior of the lampreys noted on the "fan" insofar as it slowed or 

 inhibited their entrance into the creek proper. No appreciable number 

 of lampreys entered the trap until April 25 when the mean temperature 

 of the creek ivater had risen six degrees above that in the bay 

 (Figure 15). In view of these facts I believe that the upstream migra- 

 tion of the sea lampreys entering Carp Creek began not earlier than 

 April 19 and obviously not later than April 21, 



During April 23-i-'ay 2 upstream mi grants entered the trap sporadi- 

 cally, the daily catch varying from none to seven individuals (Figure 

 15), The bulk of the migration as reflected in the trap catches 

 occurred between Iilay 2 and June 21, Of 1,61? indlid-duals talcen during 

 the entire operation of the weir, 1,U71 or 91,0 percent of the total 

 captures were talcen during this 5C-day period. There vra.s no single 

 pealc of greatest migratory activity. Instead, during the period May 3- 

 June 21, four pronounced peaks occurred, of which tho-ie on.LIay 20 and 

 June 9 are the most significant (Figure 15) « On May 20, 93 sea 

 lampreys and on June 9, 32 sea lampreys were removed from the trap. 



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