224 A BOOK ON ANGLING 



on their own offspring, while trout do greedily ; and for this 

 reason alone grayling will increase faster than trout, as this 

 source of destruction (a very large one in mere trout streams) is 

 wanting as regards the grayling. Grayling certainly are more 

 of burrowers and ground feeders than trout, and if it be thought 

 that the grayling do really diminish the trout, a little artificial 

 breeding would easily keep up the balance. But I conceive 

 that when grayling are introduced into fairly stocked pure 

 trout streams, the following change takes place : as the gray- 

 ling increase, the trout must either fall off in condition or 

 diminish in number somehow, for a stream will only support 

 a certain number of fish up to a certain size and condition ; and 

 if, for example, it holds five thousand trout you cannot put 

 five thousand grayling into it as well, and still keep up the 

 number and condition of your trout. But if, for the sake of 

 extending your sport for many months, or for the variety, you 

 are satisfied with a slight diminution in the weight of your 

 baskets of trout, then you can do well enough ; or, if this does 

 not suit, then you must resort to a large system of artificial 

 feeding. To what extent we can or could carry this point of 

 the question in an open stream, is a calculation which experi- 

 ments in fish culture, to be carried out in the future, alone can 

 assure us of. Everybody can understand that if a field of 

 turnips will support fifty sheep for a month, and you turn 

 twenty cows into it as well, the field will not support the 

 additional call made on it for the same period ; but if you 

 choose on this space to draw cart-loads of turnips, then you can 

 support any reasonable quantity of stock as long as you like, 

 and even fatten them like pigs or prize cattle, the increase being 

 regulated by the quantity of turnips you draw on. A stream is 

 in this sense a field of turnips, and you must till it and stock it 

 accordingly ; but you must not be surprised, if you starve 

 your cattle, at their being in poor condition, or even at their 

 eating each other's tails off, or even at their dying out. Gray- 

 ling do not eat trout fry, or but a very few of them, but trout 

 do devour grayling fry ; so I am inclined to give the balance 

 of destruction in reality to the trout, which is without excep- 

 tion the most voracious and omnivorous of all fish. Grayling 

 are not so easy to transplant from one river to another as trout, 

 as the ova are much more tender than those of trout, and if the 

 weather should happen to set in warm in April and May, they 

 become very difficult to hatch and rear, and very liable to go 

 off wholesale. In rivers where these fish do take, however, they 



