INDISCRIMINATE AND INCONSIDERATE PLANTING OF 



FISH. 



By Dr. James Alexander Henshall, 

 Cincinnati, Ohio. 



In the Transactions of The American Fisheries Society 

 for June, 1918, I was much pleased to read a paper by Mr. Aldo 

 Leopold entitled "Mixing Trout in Western Waters." This is a 

 matter to which I gave much thought during my superintendency 

 of the Bozeman, Montana, Station, and I am very glad that 

 the subject has been broached. 



Mr. Leopold is evidently a close observer of the streams and 

 their inhabitants in the National Forest Reserve of Arizona, and 

 has apparently given much consideration to the stocking of those 

 streams intelligently. His conclusions are exactly in accordance 

 with my own experience of twenty years in the U. S. Bureau of 

 Fisheries. After observing the results of indiscriminate planting 

 of several alien species of trout in certain streams in Arizona, 

 Mr. Leopold says, in regard to the possible hybridization of the 

 several species: 



" 1 . Species of trout spawning at the same time may hybridize. 

 More knowledge is needed on when and to what extent." 



"2. These hybrids are less productive, and therefore less 

 desirable, than pure stock. More knowledge is needed on how 

 much their reproductive capacity is reduced." 



The subject of hybridization and all speculation in that 

 direction may well be dismissed, for it rarely, if ever, occurs in 

 nature under ordinary conditions. In compliance with instruc- 

 tions, at the Bozeman station, I experimented with crossing the 

 two closely allied species, rainbow and steelhead trouts, for several 

 years. While the resultant progeny grew to be fishes of good size 

 and fine appearance, they subsequently proved to be infertile. 



In respect to stocking waters, Mr. Leopold says that the 

 National Forest Reserve Service in Arizona will hereafter follow 

 nature and stick to one species, and that empty waters will be 

 stocked with the species that seems most suitable; also that 

 stocked waters will not be further mixed, and that native species 

 will always be preferred. 



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