complete for 1956 and nearly so for 1955 

 cind 1957. Flood waters prevented enumera- 

 tion at the beginning of the chinook run 

 these two seasons. Steelhead counts are 

 not complete for any of the three seasons 

 as the trap was inoperative during part of 

 the steelhead migrating season. However, 

 the peak counts of steelhead are clearly 

 defined (see figure 5, page 4) and the 

 yearly totals represent the relative number 

 of this species passing Turawater Dam. 



Large numbers of jacks (small chinook) 

 were counted at Tumwater, and comprised 46, 

 53, and 13 percent of the chinook runs in 

 1955, 1956, and 1957 respectively. Jacks 

 are recognized by sight as the fish cross 

 the counting board. 



Time of Migration 



Blueback salmon . — The main migration 

 of blueback salmon appears at Tumwater Dam 

 from mid-July to about the middle of August. 

 Daily counts of this species for the three 

 seasons are shown in figure 3. It appears 

 characteristic of the blueback escapement 

 at Tumwater to rise to a peak in daily 

 counts soon after the first arrivals appecir 

 at the dam. In 1957 both the first arrivals 

 and the peak count were about two weeks 

 earlier than in the previous two seasons. 

 During the times when daily counts of fish 



Table 1. — Counts of adult fish passing 

 Tumwater Dam for years 1955, 

 1956, and 1957. 



955 

 956 

 957 



Figure 3. — Upstream migration - blueback 

 salmon. Tumwater Dam, I955-I957. 



were large, there remained large accumula- 

 tions of fish immediately below the dam and 

 jumping salmon were numerous at the base 

 of the dam. Thus, in addition to the num- 

 ber shown passing through the fishway on a 

 given day, many hundreds of fish were pre- 

 sent below the dam. 



W The 1955 counting season extended from 

 May 24 to December 31; the 1956 and 

 1957 counting seasons extended from 

 January 1 to December 31. 



Chinook salmon . — The daily counts of 

 chinook salmon at Turawater Dam are shown in 

 figure 4 (page 4). In contrast to the short 

 seasonal range of blueback salmon, chinook 

 are present from the end of May to late 

 September. Both spring and summer chinooks 

 pass Tumwater Dam. The designations spring 

 and summer are given chinook salmon in the 

 Columbia River system according to the sea- 

 son the fish migrate into the river. Spring 

 Chinook enter the Columbia River in April 

 and May; summer chinook in June cuid July. 

 The early part of the escapement at Tumwater 

 Dam is composed of spring chinook; summer 

 chinook appear later in the season. Tagging 

 experiments of 1954-56, in which spring and 

 summer chinook were tagged at Rock Island 

 Dam and observed at Tumwater, indicated a 



