J. PISCICULTURE AND THE FISHERIES. 415 



BREEDING SALMON AND TROUT IN INCLOSURES. 



An interesting experiment in fish culture has lately been 

 made in the North Sea by Professor Rasch, of the University 

 of Christiania. The locality is a deep " fiord," or narrow gulf, 

 running up into the land, over a mile in length, and at the 

 end narrowing to the width of a large trench, which then 

 opens out into a fine natural basin of salt water of about 300 

 acres in extent, nearly as broad as long, with an average depth 

 of 40 feet. There is a free and continual flow of water from 

 the sea through this narrow trench, or inlet, with a regular 

 ebb and flow, the difference between high and low water be- 

 ing only one foot, except in spring floods, and the water is 

 quite as salt, or even Salter, than in the sea outside. In 1869, 

 having acquired the exclusive right to the waters in this ba- 

 sin and its tributaries for three years, Professor Rasch con- 

 structed a fence in this inlet, composed of strong posts driven 

 firmly in the bottom, with twelve movable frames of galvan- 

 ized wire netting stretched between. This does not prevent 

 the ebb and flow of the tide, but effectually stops the out- 

 ward passage of the fish. In the inclosure a hatching appa- 

 ratus for salmon and sea-trout spawn was erected, connected 

 with two small fresh-water ponds, the whole supplied with 

 water from the same spring. After the proper time the young 

 are turned into the basin. They are, however, fed in the 

 fresh-water ponds, before being discharged, with fine-chopped 

 mussels (Mytilus eclulis), of which there is an immense sup- 

 ply in the salt-water basin. Fresh-water gasteropods have 

 also been introduced for a similar purpose. On account of 

 this rich supply of food, the fry soon become strong, and grow 

 with unusual rapidity. 



The question as to salmon and sea-trout living and thriv- 

 ing without entering into the deep sea may be considered as 

 answered in the affirmative as far as regards the trout, since 

 last autumn sea-trout ascended one of the brooks from the 

 salt-water basin, which had been closed nearly three years. 

 These were in very fine condition, full of ova, and weighing 

 from two pounds to four pounds. Professor Rasch has suc- 

 ceeded in producing a bastard variety of salmon and fresh- 

 water trout (Salmofario), which, being unfruitful, like all hy- 

 brids, is in fine condition, and grows to a large size, having 



