386 



The National Geographic Magazine 



SOME INSTANCES OF UNWISE INTRODUC- 

 TIONS 



The seemingly benign and beneficent 

 work of transplanting water animals is 

 not wholly free from possibly harmful 

 results, analogous to those that have at- 

 tended the transplanting of land animals, 

 of which the rabbit in Australia, the 

 mongoose in Jamaica, and thfe English 

 sparrow and Norway rat in America are 

 well-known examples. Even when such 

 transplanting is done advisedly and with 

 circumspection, there is a possibility of 

 untoward results that will offset any 

 benefits that may accrue. Injury may 

 arise from a general disturbance of the 

 "balance of nature" by the introduction 

 of new factors into given waters, or from 

 the supplanting of one kind of animal by 

 another less desirable. The ignorance or 

 indiscretion of private persons who un- 

 dertake to introduce new creatures into 

 waters in which they are interested may 

 produce most disastrous effects, while in 

 a few instances carelessness or a mere ac- 

 cident has had a far-reaching effect. 

 Great care has been exercised by the 

 Federal Fishery Bureau in making plants 

 of non-indigenous fishes, and injurious 

 results chargeable to it have been ex- 

 tremely rare ; but eternal vigilance is 

 necessary, and many applicants for fish 

 become disgruntled because they are not 

 permitted to have their own way. Fine 

 trout streams may be quickly ruined 

 through the planting therein of bass, or 

 lakes stocked with some defenseless 

 valuable food-fish may be depleted by the 

 thoughtless planting of some compara- 

 tively unimportant rapacious species. 



Some of the states have been quick to 

 recognize the necessity for restricting the 

 planting of non-native fishes, and have 

 enacted laws prohibiting the introduction 

 of any fish not approved by the state au- 

 thorities. One of the most persistent de- 

 mands on the Bureau of Fisheries is for 

 black bass to stock western waters that 

 already contain an abundance of trout or 

 salmon. Such practice is little short of 

 criminal, and in all such cases where there 



is reason to fear that valuable trout 

 waters may be ruined the Bureau takes 

 the precaution to defer to the judgment 

 of the state fishery officers. 



One of the most unfortunate instances 

 of the destruction of one species by an- 

 other is that of the grayling, a superb 

 food and game fish of which only three 

 colonies had survived some cosmic cata- 

 clysm and had become established in 

 regions as isolated as Alaska, Montana, 

 and Michigan. In the last-named state 

 trout were recklessly planted in some of 

 the few streams inhabited by the gray- 

 ling, with the result that the grayling has 

 been completely exterminated therein. It 

 is only in Tennyson's "Brook" that 



here and there a lusty trout 

 And here and there a grayling 



live in harmony together. 



With the transplanting of eastern 

 oysters on the western seaboard, there has 

 been introduced one of the small boring 

 mollusks or drills which is very injurious 

 to oysters on the Atlantic coast and is 

 maintaining its reputation in California. 

 It has become very abundant, and several 

 years ago was reported to be destroying 

 annually oysters to the value of $30,000. 



Another imfortunate case of accidental 

 or unintentional acclimatization is that of 

 the alewife in Lake Ontario. By means 

 of canals, the alewife found its way from 

 the Delaware or Hudson River into Lake 

 Ontario, and there soon became excess- 

 ively abundant; but lack of food or the 

 changed habitat resulted in a stunted 

 race of no economic value, and fiu-ther- 

 more this fish is subject to a periodical 

 epidemic which kills millions each season ; 

 these pile up on the shores or pollute the 

 water, and prove such a menace to health 

 that the local authorities are often put to 

 considerable expense in removing them. 

 It is possible, however, that by serving as 

 food for other fish the alewives in Lake 

 Ontario are saved from the stigma of 

 being unmitigated nuisances. 



Another untoward aspect of the ac- 

 climatizing of native fishes is the annoy- 

 ance or confusion which may come to 



