16 



AETIFICIAL PROPAGATION OF PACIFIC SALMONS. 



The upper end of the flshway of the old dam was left iu place, the narrow 

 passage between it and the new trap protecting the spaces at the south end of 

 the barrier from the current and from drift. These spaces have been racked 

 above and below to form commodious pens for males and unripe females. The 



south end of the barrier 

 is protected by a substan- 

 tial abutment. 



The maintenance of the 

 racks in Phinney Creek 

 has been a very heavy 

 item of expense in past 

 years, and the trap was 

 frequently carried away 

 by freshets just at the 

 height of the season, al- 

 lowing large numbers of 

 fish to escape and con- 

 siderably reducing the 

 season's take of eggs. 



Concrete piers have 

 been used in some of 

 the California rivers, 

 but they are now con- 

 sidered too expensive 

 for fish-cultural work 

 on an economical scale. 

 In some of the streams 

 in that State piles are 

 substituted for trestles. 

 These are sawed at the 

 proper angle, capped 

 \Anth timbers of the 

 right size, and used 

 for supporting the 

 rack stringers. In con- 

 structing racks' in this 

 way the pickets are 

 usually placed in sec- 

 tions and hoisted into 

 position by means of a 

 derrick. Mudsills are 

 embedded in the gravel 

 beneath the rack and 

 a floor placed thereon. 



OBTAINING SALMON FOR 

 PROPAGATION. 



The manner of cap- 

 turing the brood fish 

 varies in accordance 

 with the nature of the 

 stream where the work 

 is conducted. On some rivers the upstream trap is successfully used 

 m connection with the head rack (PI. 1). The tray used is sometnnes 

 a square or oblong inclosure ; at other times it is a pen constructed 

 of lumber. In either case the entrance is made on the principle of 



