20 ARTIFICIAL PROPAGATION OF PACIFIC SALMONS. 



10 feet in dimensions, 6-incli sides, and legs about 3 feet long, with a 

 slope toward the operator at the other end. Across the table, for 

 convenience in taking the eggs, is pla; ed a small platform or bridge 

 1 foot in width, with a slope of about 30° toward the upper end of 

 the table, the face of which is studded with sharp-pointed nails one- 

 half inch long to hold the fish in place. 



The spawn taker removes a fish from the table and places it on 

 the platform with the head toward him, his left hand resting near 

 the middle of its back. With his right hand he rips open the ab- 

 domen from a point between the pectoral fins to the egg vent by 

 means of a sharp-bladed knife, having a guard which permits the 

 blade to project tliree-fourths of an inch. If the eggs are ripe they 

 are easily removed by slightly inclining the fish toward the lower 

 side of the board, where they gently fall into a pan placed to re- 

 ceive them. The dead fish is then thrown aside and the operation 

 repeated. After two females have been spawned a man at the op- 

 posite side of the table removes the pan, replaces it with an empty 

 one, which has first been moistened with water, and passes the pan 

 of eggs to the operator handling the male fish, to be fertilized. After 

 fertilization has been accomplished, the eggs are turned into a wash- 

 ing box and held in a quiet current in the stream to clean up. This 

 box somewhat resembles a corn popper in its construction, being 

 made of fine-meshed wire and provided with a long handle and a 

 hinged cover, with a clasp to hold it in position, tn its bottom is 

 a small trapdoor, operated by a lever near the end of the handle. 

 After remaining in the stream a few minutes the eggs are emptied 

 through the trapdoor into a bucket submerged about a foot under 

 the surface of the water. Here they are held for half an hour to 

 harden and are then carried to the hatchery, measured, and dis- 

 tributed in standard salmon-hatching baskets, 50,000 being placed 

 to a basket. 



HATCHING APPARATUS AND METHODS. 



The hatching apparatus usually employed is the so-called stand- 

 ard salmon trough, with wire-cloth baskets. The troughs, which are 

 generally constructed of cedar and redwood from 1| to 2 inches, 

 dressed, are 16 feet long, outside measure, and 14 by 6^ inches, inside 

 measure. They are arranged in pairs, two or three pairs being 

 placed end to end on different levels, with a fall of about 6 inches 

 between each pair. 



Metal partitions divide each trough into compartments just 

 enough longer than the baskets to permit of their being raised and 

 lowered and subjected to slight tilting. The essential feature of this 

 trough is the perfection of water circulation attained by means of 

 cross partitions or riffle dams inserted at either end of each compart- 

 ment. These partitions are made of No. 20 galvanized sheet iron 

 and are held in place by saw scarfs in the sides and bottom of the 

 trough. 



The first riffle dam is placed 7i inches from the head end of the 

 trough, reaches entirely across, and extends from the bottom to 

 Avithin about 1| inches of the top. Two inches below this point 

 a similar dam extends across the trough, reaching from the top to 

 Avithin 1| inches of the bottom. Twenty-six inches farther down 

 similar dams are arranged, and so on throughout the entire length of 



