ALASKA FISHEBIES AND FUK INDUSTKIES, 1911. 87 



object and purpose of fish-cultural operations, viz, to increase the 

 productivity of the waters. No matter how thorough the work in 

 the hatchery proper may be, no adequate or justifiable return can be 

 expected unless every possible precaution is likewise taken to conclude 

 the process properly. There is no justification whatever for artificial 

 or, perhaps, as it may be termed "protected," propagation where the 

 returns to the waters are not made in the most scientific and intelli- 

 gent manner possible. Otherwise it were better to let nature do the 

 work. 



Especially is there lack of consideration as to the proper age at 

 which to plant young fish, and again as to the selection of places for 

 releasing them in order to give the best results. 



With the means ordinarily at command the best results are obtained 

 by planting young red salmon when the umbilical sac is about two- 

 thirds absorbed, which is the time when the fry begin to swim up 

 freely. It may sometimes be necessary to plant before the sac is 

 sufficiently absorbed in order to relieve a congested condition in the 

 hatchery, for fry require much more trough space than eggs; but 

 so far as possible the planting of fry before the sac is two-thirds 

 absorbed is to be guarded against. With the temperatures prevailing 

 at the Alaska hatcheries this means that the fry must be held at least 

 four or five weeks after hatching. Fry take food some time before 

 the sac is entirely absorbed, the desire to eat being first apparent to a 

 noticeable degree about the time they begin to swim up freely. 



Usually the best planting grounds are rocky places and areas more 

 or less covered with vegetable growths, where the young fish may be 

 scattered to give them all the protection possible from predatory 

 fish and other natural enemies and at the same time afford an adequate 

 supply of natural food. 



It is better ordinarily to take the fish out and plant them than to 

 allow them to pass of their own free will into the pond outlet and 

 thence to the stream or lake, for in the latter event the school of 

 trout and sculpins collected at the outlet where the young salmon 

 leave the protection of the pond is certain to cause much loss. 

 If possible, it is well to plant the fish in roily water, thus making it 

 difficult for trout and other enemies to observe and devour them. In 

 the planting of chinook salmon in California it has been the practice 

 upon various occasions to shovel in clay or other earth at a point near 

 where the fry were being planted, thus to create an artificial turbidity. 



In Alaska the plan of seining or netting schools of trout from the 

 vicinity of the salmon planting grounds is a worthy practice. The 

 trout are of no value in the region save occasionally when used by 

 natives, and their d^truction works as a distinct benefit to the 

 salmon industry. It h^ been found of advantage at some hatcheries 



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