410 A HISTORY OF FISHES 



finest Trout fishing in the world. American Trout of various 

 kinds have been introduced into England ft-om time to time, 

 and our own Brown Trout introduced into the United States, 

 but neither of these experiments can be described as an un- 

 qualified success. The only foreign species at all well known 

 in Great Britain is the Rainbow Trout. This has been used 

 extensively for stocking sporting waters, but, although it has 

 sometimes bred for a few seasons, it has very rarely become 

 permanently established under natural conditions. Compara- 

 tively recently, Trout have been introduced with great success 

 into Tasmania, Ceylon, Kashmir, South Africa, Kenya Colony, 

 etc., in every case for sporting ends, and during the last year 

 or two it has been suggested that the American Black Bass 

 should be planted in Lake Naivasha in Kenya. However much 

 such introductions of foreign species may benefit the sportsman, 

 they are to be wholly deprecated by the biologist, who wishes 

 to study the indigenous fauna of a country under normal 

 conditions, and it has been found necessary to enter a strong 

 protest against these interferences with natural conditions. It 

 is v/ell known that the introduction of new elements into a 

 fauna may upset the balance of nature and produce quite 

 unexpected results, and the new species may even become a 

 serious pest and defy all eflforts to exterminate it. It is said that 

 the Carp in North America and the Goldfish in Madagascar have 

 spread and done considerable damage to the existing fisheries 

 for other and better fish, and the Trout in New Zealand have 

 aflfected the fisheries for Eels and Crayfish. In the Great Lake 

 of Tasmania lives a most interesting crustacean of an archaic 

 type, which is found nowhere else in the whole world: the 

 introduction of Trout into the lake has played a considerable 

 part in the decimation of this creature, which is now confined 

 to a very Hmited area and is in serious danger of complete 

 extinction. 



As far as the British Isles are concerned, it has already been 

 pointed out that, apart from migratory species such as the Eel 

 and the Salmon, the fresh-water fishes are of very little value 

 as a potential source of food supply, so that the artificial propa- 

 gation of Trout is looked upon by many as of very slight economic 

 importance. For the same reason, it may well be argued that 

 the decline which is known to have taken place in the stock 

 of fresh- water fish in England and Wales during the last hundred 

 years is comparatively unimportant, and that the expenditure 

 of any public money in maintaining or improving the stock is 



