FISH-CULTURAL PRACTICES IN THE BUREAU OF FISHERIES. 727 



latter by large spikes. Against these poles or inclined uprights rest the gratings 

 of the rack, which for the sake of convenience in handling are built in sections 

 6 feet wide and from 6 to 10 feet long to suit the varying depth of water. The 

 gratings are made of i yi by 3 >2 inch slats of dressed lumber set i ^ inches apart, 

 their thin edge facing the current, the edge being convex to facilitate cleaning, 

 and permit the passage of leaves. The ends of the gratings are nailed between 

 two pieces of i>^ by 4 inch material, notched into the slats to make a flush 

 surface. The space between the slats is gaged by nailing on i >^ by 4 inch blocks 

 to each end. The longer gratings are braced with two strips i^ by 4 inches 

 nailed on 3 feet from the bottom. 



In the upper rack is placed a trap 10 feet square with vertical slat sides 

 similar to the rack gratings and having a solid board bottom. The narrow 

 opening which allows the fish to enter is so constructed as to reduce to a mini- 

 mum their chance of escape. The trap is primarily used for observing the 

 general condition of the fish in the pool prior to the beginning of seining or 

 spawning operations. 



The retaining rack is at the lower end of the pool, where the stream narrows 

 to about 190 feet. It is supported on 6 stone-ballasted crib piers with sides 14 

 feet long, made by spiking together logs 8 to 12 inches in diameter until the 

 required height is reached. The piers are built on shore, floated into place, and 

 filled with rock. Across the upstream end of each pier are two 10 by 10 inch 

 stringers laid parallel and supporting a board walk, as in the upper rack. 

 Two small temporary piers are also built, to support the shore ends of the rack. 

 Gratings having 2-inch interstices are placed across the stream, similar to those 

 in the upper rack, with the exception that 5 openings 2 feet wide are left between 

 the piers nearest the center of the stream. These openings are covered by the 

 usual traps, which extend upstream into the pool 9^^ feet. The traps are 4 feet 

 in height and 6 feet in width at the entrance, being shaped to fit the slant of the 

 gratings. The sides are of 1 5^ by 4 inch material spaced 2 inches apart, and 

 with the broad edge toward the current. Braces are placed across the top, and 

 at the apex of the trap is an opening 3 inches in width from the surface of the 

 water to the bottom. The salmon pass into the pool through this opening and 

 rarely, if ever, find their way out. 



Before the installation of the retaining rack, some ten years a^o, many eggs 

 could not be collected by reason of the loss of fish from their running back down- 

 stream. This violation of the natural instinct of salmon to work ever upstream 

 was due to fright resulting from the continual sweeping of the seine just below 

 the upper rack. In the early days Indians were engaged to walk on either shore 

 for a mile or so below the rack and beat the water with brush in an endeavor to 

 drive the fish up to the seining ground. Since the installation of the retaining 

 rack such measures have been entirely unnecessary. 



