in tavD of these nests spa-vming had been completed. On May 26 ^ 

 construction had been started on, or spawninf: had been com- 

 pleted in, 35 nests in this area. The mean daily imter tem- 

 peratui'e on this date had risen to 55.0 degrees ?. (range: 52-58 

 degrees F.)- Further temperature rise was accom.panied by tfirc 

 waves of* spaTming activity in the 0.5 -mile portion from Stations 

 IL to U't, one vras between J-une 1 and 5 axid the other between 

 June 10 and 16 when the mean daily ivater temperatures rose to 

 and varied betvreen 60.5 and 66.5 degrees F„ and -eTiien daily fluctua- 

 tions seldom dropped belovr 60 degrees F. The decline in nest 

 building and spaiming activity between June 6 and 9 accomp3.nied 

 a recession in water temperatures from the irdtially high temper- 

 atures of the period, June 1 to 5- The last spavming activity 

 observed in this area irvas on July 5 when eight spai'ming or spent 

 sea lampreys were observed between Stations IL and IM. The mean 

 daily ivater temperature on -ohis date was 7O.O degrees F. 



Spaivning activity, -wiiich commenced just below Ocqueoc Falls, 

 was restricted until June 1 to a 0.5-mile area (Stations IL-IM) 

 immediately below the falls. On that date nest construction 

 began at Stations IE and IK in the lower readies of the zone. 

 Peair activity at these stations followed that in the area imoie- 

 diately below the falls by an appropriate period^, as in the pre- 

 vious year. 



On June 5j spa^vning activity commenced more or less uniformly'" 

 throughout Zone 2 above the Ocqueoc Falls (Stations 2 A, E, H, 

 and I). At this time, mean daily water tem.peratures were 66.0 

 degrees F, or higher. The peak of spa^'vvning activity occurred 

 between June 8 and 15 and had ceased entirely in Zone 2 by June 22. 



Again, as in 19h7 > belated spavming acti"5n.ty took place below 

 Ocqueoc l^ke (Stations 1A.~1B). First spaiTning was observed here 

 (station 13) on June 16^ thereafter, it continued erratically 

 until July 28 when two pairs, the last seen in this season, spavi/ned. 

 Mean daily water temperatixres during this period varied from 63. 

 to 75-0 degrees F. 



A graphic comparison of the duration and ijitensity of sea 

 lamprey spaiming in 19U8 below Ocqueivc Lalce (Station 13), below 

 the Ocqueoc Falls (Stations IL-IM), and at the head of Zone 2 

 (Station 21) is presented in Figure 29- Mean daily water temper- 

 atures hs.ve been plotted in this figure to show their variation 

 ixi relation to the onset and initial increase iji the intensity 

 of spawning activity. 



- 89 - 



