FISHERY BULLETIN: VOL. 70, NO. 2 



Figure 1. — Brooks Lake, Alaska, showing three lateral tributaries where spawning sock- 

 eye salmon were studied in 1959, 1960, and 1961. 



Raleigh, 1964). I observed fish joining schools 

 off the stream mouths even after some fish had 

 entered the streams and begun spawning. These 

 late-arriving fish usually spent several days in 

 the school before they ascended the stream. 



In some years all adult sockeye salmon that 

 entered the study streams were passed through 

 weirs. Weirs were operated at Up-a-tree and 

 One Shot Creeks in 1961 (Table 2) and at Hid- 

 den Creek in 1959, 1960, and 1961 (Table 3). 

 To insure that all fish in the run were counted, 

 the weirs were closed when fish first appeared 



off the stream mouths. The fish were allowed to 

 pass upstream through a counting gate when- 

 ever 10 or so appeared immediately downstream 

 from the weir. 



Although spawning sockeye salmon were con- 

 stantly present in each study stream for several 

 weeks, they tended to enter the streams in waves 

 or pulses. Fish entered Hidden Creek in several 

 distinct waves in 1959 and 1960 but not in 1961 

 (Table 3) . However, the weir records for Up-a- 

 tree and One Shot Creeks suggest the presence 

 of more than one major influx of spawners in 



Table 1. — V^atershed area, total length, and physical characteristics of portions of streams accessible to salmon in 

 Hidden, Up-a-tree, and One Shot Creeks, tributaries to Brooks Lake, Alaska. 



Portion accessible to salmor» 



Stream 



Watershed 

 area (km^) 



Percent gradient 



n spawning areas 



[range) 



448 



