20 U. S. BUEEAU OF FISHERIES. 



opposite side to give greater rack surface. It is well to operate 

 a somewhat coarser rack than that required to stop the small trout 

 at a suitable point above where floating leaves and other debris 

 may be stopped and removed, thus reducing the liability of the 

 trap racks to dam up and undermine. The location selected for 

 the trap is very important. Other conditions being favorable, it 

 should be placed as near the mouth of the stream as the character of 

 the banks will permit with the V-shaped entrance lead toward 

 deepening water. 



The fish run most freely on dark, rainy nights when the stream is 

 rising, but during the spawning season ripe fish will enter night 

 after night in times of normal stream flow. The majority of the 

 fish are usually taken while one or two heavy rains are bringing the 

 streams to flood stage. At such times it is necessary that the attend- 

 ant have an assistant to keep the racks free from debris, as the 

 fish often enter the trap as fast as one person can readily transfer 

 them with a large dip net from trap to pens. Not infrequently 

 as many as 1,000 to 3,000 fish are taken in a night. If ample 

 rains are lacking at the height of the spawning season and the 

 water is very low, only a few fish will ascend to the traps, and 

 the egg collections will be relatively small unless the fish can be 

 taken by seining the lower stretches of the stream. An abundance 

 of rain late in the season will have little influence in bringing 

 spawning fish to the traps. 



A comfortable cabin in close proximity to the traps is a necessity, 

 as the constant care of the racks and the work of guarding the fish 

 against predacious animals and malicious persons often subject 

 the attendants to great hardships during inclement weather. 



TAKING THE SPAWN. 



T\'lien the fish are running briskly, no attempt is made to separate 

 them, but as soon as the run slackens they are carefully assorted and 

 segregated in pens according to their degrees of ripeness. This saves 

 much time and possible injury to the fish through constant handling 

 for the purpose of ascertaining their spawning condition. A per- 

 centage is kept of the ripe fish taken from each pen so that the proper 

 time for handling those in the various inclosures may be determined. 

 It is sometimes necessary to examine every day or every other day 

 the fish that appear to be nearly ripe and others from once to twice 

 a week. 



Eggs are not ripe enough to be taken until they flow readily under 

 very slight pressure. In some instances a fish may by muscular con- 

 traction retain its eggs for a few seconds, deceiving the spawn taker 

 for the moment, but if the eggs are ripe they will begin to flow as 

 soon as the muscles relax. 



The eggs are taken in pans or other metal vessels which have been 

 thinly coated with asphaltum to prevent rust or in receptacles made 

 of pressed fiber, the advantage of the latter being that they do not 

 require painting and do not transmit cold as readily as the metal 

 vessels. Just before the eggs are taken the vessel is dipped into cold 

 water and drained. 



The spawn taker holds the fish as firmly and gently as possible at 

 such an angle as will cause the ripe eggs to flow naturally toward the 



