43 



At Howietoun I use boxes, each of which will rear 15,000 

 Lochleven Trout fry for five or six months after hatching, and 

 this without any appreciable loss, but I do not care to lay 

 down more than 20,000 eggs on the grilles in each box, the 

 size of the egg being 35,000 to the gallon. I find that if the 

 eggs are laid down any thicker than this there is a decided 

 difference in the vitality of the alevins and feeding powers 

 of the fry. 



I will now consider the Hatchery as a factor in the culti- 

 vation of migratory Salmonidae, restricting myself for the 

 present to those species placed by Dr. Giinther in the 

 group Salmones either with a wide geographical range, as 

 Salar, Trutta, and Cambracus, or limited to Great Britain 

 and Ireland, as Brachypoma and Gallivensis, merely point- 

 ing out that while touching on the general conditions 

 common to the increase of the above named species, the ex- 

 termination of the Bull Trout on the Tweed and the Sea 

 Trout on the Forth forms a very serious point to discuss in 

 treating of the culture of the Salmon, and that the best results 

 can only be obtained by the careful protection and arti- 

 ficial production of the species best suited to each particular 

 district. The objects here are to increase Salmones whose 

 pastures are in the sea, and whose nurseries are in the rivers. 



The size of the river has no fixed relation to the number 

 and weight of fish caught in its estuary and contiguous sea- 

 board, and if a very large number of smolts were annually 

 turned in immediately above the tidal waters the stock of 

 Salmones would be increased by a proportion of the number 

 turned in, fixed only by the conditions of food and of 

 natural enemies in the estuary and adjoining sea. I do not 

 mean to say for an instant that all the fish reaching 

 maturity would return or attempt to return to the mouth of 

 the river in which they were liberated as smolts, but I think 



