PACIFIC SALMON FISHERIES 635 



only those eggs which become embedded beneath several inches of sand and gravel 

 produce alevins which live to attain tlie fry stage; and that tliose eggs which are 

 not covered l)y several inches of sand and gravel are eitlier consumed by active 

 aquatic enemies or destroyed by vegetable molds, connnoniy termed "fungus." 



My experiments have demonstrated tluxt the burial of freshly fertilized eggs of 

 the nerka and other Pacific salmon does not smother them ; that eggs so treated not 

 only live but liatch; and that if they are covered to a sufficient depth the alevins 

 produced survive and possess the instinct and power to work their way gradually 

 to the surface; that if buried beneath 5 or 6 inches of sand and gravel such eggs 

 will hatch, and the young will work their way up through the sand and gravel to 

 the surface, and that by the time they emerge, have absorbed their sacs and are 

 then exempt from the attacks of vegetable molds. 



Eggs buried under 1 or 2 inches of sand and gravel produce alevins that work 

 their way up to the surface before the sac is absor))ed, and upon reaching the sur- 

 face are subject to attack by vegetable molds, and a very large percentage are 

 thus destroyed, as well as by the more developed forms of aquatic life. 



Eggs buried to a depth of 3 inches produce alevins that work their way to the 

 surface so gradually that by the time they reacli the surface their sacs are so nearly 

 absorbed that many, but not all, resist the effects of fungus. Alevins from eggs 

 buried beneath less than 4 inches of sand are liable to reach the surface while the 

 sac is so thinly covered that few, if any, survive the effects of fungous growth. 



The spawning beds of Pacific coast streams from California to Alaska (to which 

 my observations have been confined), where the salmon spawn in numbers are, 

 during and after the spawning period, covered with more or less vegetable molds. 

 These molds are particularly common in the beds of streams where great numbers 

 of salmon have spawned and died. Every experienced fish culturist knows that 

 most waters carry great numbers of spores of fungi, and how difficult it is to pre- 

 vent eggs and alevins from being attacked and injured by their growth. I 

 believe that in natural propagation fungous growths destroy more salmon eggs 

 and alevins than all other causes combined. The vegetable molds of Pacific 

 streams are not active beneath the surface of the beds of streams. Salmon eggs 

 cast therein, if even thinly covered with sand, are not injured by them. These 

 molds do not affect the fry that have nearly or entirely absorbed their sacs, but 

 they are deadly if permitted to attach themselves to either the eggs or the alevins. 



My experiments along this line lead me to express the opinion that by the burial 

 of freshly fertilized salmon eggs under 6 or 7 inches of sand and gravel strong 

 healthy fry can be produced at less cost than under existing hatching methods, 

 and that fry so produced are stronger and more capable of resisting the attacks 

 of their active enemies. 



I trust that this short statement of my experiments in the burial of salmon 

 eggs may be deemed of sufficient economic importance to stimulate fish culturists 

 generally in experimenting along similar lines. Those who do will perhaps 

 experience some difficulty at first in the covering of a large number of eggs. 

 Experimenters will find that after preparing suitable beds of sand and small 

 gravel the eggs can be evenly laid and held until covered, if the surface of the bed 

 is first thickly indented with cells a little deeper than the eggs. This can be 

 readily accomplished by stamping the bed with a board covered with projections 

 or pegs of suitable size. 



My experiments suggest that in the near future most of the buildings and 

 hatching apparatus now used in the propagation of salmon and trout will be 

 dispensed with; that after the eggs have been expressed and fertilized, instead of 

 being placed in wire baskets in hatcheries, they will be buried beneath the sand 

 and gravel of the beds of natural or prepared streams, and that with the exception 

 of watchmen to protect them, little or no other labor will be required. 



The subsequent deA/elopment of this practice has been largely 

 confined to British Columbia. Some 30,000,000 eyed eggs were 

 planted in inaccessible waters by the Canadian hatcheries in 1927. In 

 the United States such plants have been made in only a limited 

 number of instances. 



REARING SALMON FRY 



For many years it was the custom to plant the fry as soon as they 

 had absorbed the yolk sac, a period of about 30 days. A few thou- 

 sands were sometimes raised to the fingerling, yearling, or adult 



