American Fisheries Society. 61 



conditions during' the ova stage, and thus bring into existence 

 immensely increased numbers of young' fish. To appreciate fully 

 the significance and importance of artificial propagation as a 

 factor in fishery pro])lems, we must ever keep in mind this won- 

 derful margin of gain over natural propagation. 



Fish culturists and all who have carefully investigated the 

 subject are unanimously agreed that the treatment and protection 

 we extend to the ova multiplies hatching results five hundred to 

 one thousand times, and some place the ratio much higher. Nor 

 is this enormous disparity to be wondered at when we inquire 

 into the conditions, and understand the dangers and perils to 

 which the spawn as deposited in nature is constantly exposed. 



But taking the most conservative estimate, five hundred, as 

 a basis, and it will be seen that we produce as many fish from 

 one pair of adults as nature does from five hundred, or that 

 one million ova artificially treated is ecjual to half a billion on 

 natural spawning beds. Or, to put it another way, five hundred 

 pairs of breeders must be allowed to reach their spawning beds 

 and spawn undisturbed to accomplish what we arc able to, simply 

 Dy lifting a single pair from the same beds and submitting the 

 ripe ova to the treatment and protection called artificial. While 

 the ova on spawning beds has its uses in the econonn- of the 

 waters, serving, as it does, as a source of food for other fish, 

 yet so far as reproductive results are concerned, 499 out of every 

 500 pairs may as well never spawn at all, provided always that 

 the solitary remaining pair falls into the hands of a hatchery ex- 

 pert at the proper time. It will readily be seen, therefore, that 

 compensation for the removal of adults is possil)le only when 

 they are taken from spawning grounds, and absolutely impossi- 

 ble only when taken elsewhere. 



It should not be inferred that an indiscriminate throwing 

 down of the barriers to the capture of adult fish is advocated. 

 Many species of fish guard their spawning beds and protect their 

 ova and young from the ravages of natural enemies, performing 

 functions that correspond with the parental care and solicitude 

 of land animals, thus producing a large natural increase. These 

 should be surrounded with all manner of safeguards and afforded 

 the most ample protection during their breeding season. 



But there are many species of fish whose ova yields readily 

 to the methods of artificial propagation, that desert their spawn- 

 ing grounds the moment the spawn is cast, leaving the defence- 

 less germs wholly unprotected, to be mercilessly destroyed by 

 by a hungry horde of spawn eaters. Now, when fish of this class 



