86 NATURAL HISTOEY OF THE SALMON. 



river, would have produced one matured fish 

 to each 6000 ova so deposited. Then arises 

 the question, how many smoults were raised and 

 liberated out of the 300,000 eggs? We think 

 we may calculate upon 30,000, or 1 in 100 

 of the quantity sent to the sea. We have no 

 means of ascertaining the quantity that did 

 return; but one thing is certain, that we are 

 enabled, by artificial means, to send to sea a vast 

 deal more smoults than would have gone had the 

 same quantity of ova been hatched in the river, 

 where it is exposed to all its enemies for the space 

 of fifteen months. We also know that, just in 

 proportion to the quantity of smoults migrating 

 to the sea, an increased or decreased quantity 

 return to the rivers. We know, also, that the 

 smoults go to the sea in millions, and the only 

 return we get as grilse and salmon is the com- 

 paratively few thousands that we catch. Expe- 

 rience proves to us that the produce of 12,000 

 salmon would be at least 72 millions of ova, and 

 yet, from this vast quantity of seed, we have 

 returned as salmon only as many fish as are pro- 

 duced from the ova of two or three fish, or, say 

 one fish for 6000 ova. It is evident that the loss 

 in the rivers is great; and of the amount that 



