in 



Q 



in 



D 

 O 



X 



I- 

 — 4 



VI 

 <D 

 O 



UJ 



q: 



iij 

 o 



z 



X = 4,II5 

 Y=I.80I + I03(X) 



45 



— r- 



50 



55 60 



MIDEYE-FORK LENGTH (CM.) 



65 



Figure 6.-- Relation between numbers of eggs and 

 mideye- fork lengths of 38 sockeye salmon sampled 

 at Brooks Lake, 1957. 



RELATION OF DISTRIBUTION ON 

 THE SPAWNING GROUNDS TO TIME 

 OF PASSAGE AND ABUNDANCE AT 

 THE WEIR 



To follow their distribution on the spawning 

 grounds, adult salmon were marked daily at the 

 weir with Petersen tags near the insertion of 

 the dorsal fin. Three color combinations were 

 used (red- white, red-yellow, and green-green) 

 to distinguish fish from the early, middle, 

 and late portion of the run (table 2). Only 

 vigorous fish were tagged. No dead tagged fish 



were observed in the clear water on the lake 

 after being released, indicating that tagging 

 mortality was nil. 



To provide equal representation throughout 

 the run, each day we intended to tag 2 percent 

 of the previous day's total number of adult 

 migrants. Through an oversight, however, 

 slightly more than 2 percent were tagged. 

 For each tagged fish observed migrating 

 downstream and later observed migrating 

 back up through the weir, untagged fish should 

 have been accounted for, either by down- 

 stream count or deduction from the day's 

 total. 



The net number of each color combination 

 remaining in the lake after deducting those 

 which migrated out of the lake indicated that the 

 early run was primarily fish destined for 

 Brooks Lake tributaries and the late run was 

 fish destined for Brooks River. The middle run 

 was a mixture of both (table 2). 



Spawning surveys on foot were begun July 

 26 on Up-a-tree Creek and ended September 28 

 on Brooks River. Surveys were made at weekly 

 intervals during the spawning period on each 

 stream. Two men made the surveys. One re- 

 corded data and carried a rifle for protection 

 from brown bears; the other examined the fish 



TABLE 2. — Number of salmon tagged and tags sighted at the weir from early, 

 middle, and late portions of Brooks Lake sockeye salmon run, 1957 



Includes two tag scars, one assumed red-yellow and one green-green. 

 Includes one tag scar, assumed green-green. 



