Fluctuations in water level and. volume of flow and the pre- 

 sence of some turbidity ivLth rising waters had no evident influence 

 upon sea lamprey spawning except insofar as they were related to 

 changes in water temperature. 



The weather in successive years vai'ies so greatly, with conse- 

 quent effects upon stream conditions, that the assignment of the 

 spawning season to calendar periods is an unreliable procedure. 

 In general, however, sea lamprey spaivning in the Ocqueoc River may 

 begin as early as the last week in May and continue until the last 

 week in J\ily. The pealc of spaiiming activity evidently occurs some- 

 time during the first three weeks in June and usually lasts about 

 two weeks. 



In I9IJ.7, the first sea lamprey nest was constmcted on the 

 night of June 3-U about one-half of a mile below Ocqueoc Falls 

 (station IL-IM; 8.8 miles above mouth). The mean ivater temperature 

 during this period vras ^3.0 degrees F. (range: 50-55 degrees F.). 

 Forty-eight hours later, when the mean daily water temperature had 

 risen to 56.0 degrees F., 28 nests had been built in an area 750 

 feet long ii/hich included the first nest. The peak of spa\iniing 

 activity in the 0.5-mile stretch immediately below the Ocqueoc Falls 

 (station IL-ll/l) occurred between June 16 and 23 vihen the mean daily 

 water temperatures ranged between 53.0 and 67. degrees F. and the 

 daily fluctuations seldom fell below 60 degrees F. Sustained drops 

 below the 60-degree level brought corresponding declines in nest 

 building and spawning activity. By July 3j spavming activity in 

 this area was virtually concluded j only 21 spawning or spent sea 

 lampreys Tvere found in the river bet-vvBen Stations IL and IM on this 

 date. 



In Zone 2, the peak of spawning activity folloTved that below 

 the falls in Zone 1, hj about five days. On June 25, neither spavm- 

 ing nor spent sea lampreys could be found in this area. 



On June 25, spa'vvning activity was first noticed below Ocqueoc 

 Lalce (stations lA-lB). It continued sporadically there until July 

 19 ivhen the last spawning pair was observed (mean daily water tem- 

 peratures, June 25-July 19 t 66 to 73-0 degrees F.). 



In I9U8, all areas of the river were Thatched closely for the 

 beginning of spaivning and after that was observed, spa^vning activ- 

 ity irns followed closely in six sample areas distributed throughout 

 Zones 1 and 2. 



The spring of 19U8 Tras warmer and earlier than in 19U7. The 

 first nest was constructed on May 22 in precisely the same riffle, 

 a short distance below Ocqueoc Falls, on iihich the first nest built 

 in I9U7 f/as found. The mean daily water temperature on this date 

 was 53.0 degrees F. (range: 51-55 degrees F. ). On May 2k, in a 

 750-foot reach below Ocqueoc Falls, Ik nests had been started and 



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