i 



30 5 



APRIL 



15 20 25 30 



MAY 



10 15 20 25 30 5 10 



JUNE JULY 



Figure 2.— Daily percent of total sea lampreys lifted at the Holyoke fish lifts each year, 1980-83. Temperatures are the daily 

 maximum river temperatures. The lifts began operating about 1 May in all years and ceased about 15 July. Wavy line near the 

 base of each panel identifies days on which the lifts were not operated. 



751 



