^'^^rs: 



Figure 7.— Bear-mutilated sockeye salmon found alive on survey of Hidden Creek in 1957. 



SPAWNING BEHAVIOR 



An important objective of the 1957 program 

 was to learn some basic facts about sockeye 

 salmon spawning behavior in the Brooks sys- 

 tem. On Brooks River, 400 yards below the 

 lake, observations were made daily from 

 August 16 through October 7 (except for 6 days) 

 from a portable 20-foot high aluminum scaf- 

 fold. The tower overlooked a gravel riffle 

 used extensively for spawning. A grid system 

 (fig. 8) was constructed over the area to 

 facilitate location of redds and to orient 

 spawning observations by reference points. 

 The area was 75 feet wide (the width of the 

 river) and 285 feet long and was portioned 

 into 15- foot squares. The portioning was ac- 

 complished by driving aluminum weir pickets 

 at 15-foot intervals on each bank of the river 

 and tying lines between them; then small 

 colored cloth strips were tied to the lines at 

 15-foot intervals, dividing each row into five 

 sections. Rows were assigned numbers, and 

 the five sections within the rows were also 

 numbered. Each of the five sections was visu- 

 ally segregated into an imaginary quadrat. 

 An abbreviated code was used to indicate a 



desired point: For example, R.S B referred 

 to row 6, section 2, the upper right quadrat. 



Sections 12 through 15 of the grid (fig. 8) 

 were used to test the hypothesis that stream 

 bottoms with loose gravel are used more by 

 spawning fish than stream bottoms with com- 

 pact gravel. Alternate 7|-foot-wide strips 

 of gravel in rows 12 through 15 were loosened 

 with a hand shovel before the onset of spawn- 

 ing. The positions of redds within this area 

 on 3 different days were as follows: 



Total 



63 



71 



I had noticed during surveys of streams 

 in Oregon that salmon seemed to choose 

 spawning areas where the gravel was 



11 



