FISH-CULTURE. 99 



SEASON 1873-74 FISH-CULTURE. 



In the autumn of 1873 I collected about thirty small trout 

 from the hill burns on Sauchiemuir, and confined them in the 

 Francis box, which was placed in the stream in Middlethird wood. 

 On October 23d I went to the box in the morning as usual, and I 

 found all the fish dead. The night previous had been very stormy 

 and wet, the stream had risen, and brought down fresh-fallen 

 leaves in thousands. The grating which admitted the water had 

 clogged, and the flow through the box stopping, all the fish were 

 suffocated. Next day I invented the leaf-screen. This was my 

 first experience of fish-culture. A week later I caught a few more 

 trout, and obtained some 3000 ova. 



I liberated the kelts, and filled the Francis box with stones 

 and gravel to the level of the overflow. I then buried the eggs in 

 the gravel, and dug them up once a week to see how they were 

 getting on. This killed some, and the sediment from the stream 

 clogged up the interstices between the bits of gravel, and smothered 

 the rest. Why do not eggs laid by trout and salmon in a river 

 die from this cause ? The answer is twofold : first, that many of 

 the eggs deposited do actually perish, and this is one of the ways 

 in which drainage affects the supply of fish in the inland waters ; 

 and, secondly, that the parts of the river bed chosen by the fish 

 are those where the current to a great extent prevents the deposit 

 of sediment amongst the gravel. Again, in many parts of a river, 

 especially those parts chosen for redds, there are springs of pure or 

 at least filtered water rising through the gravel. These conditions 

 not being present in the Francis box, it is only suitable for hatch- 

 ing ova when it is supplied with very pure water. By the end of 

 December I had very few eggs left, so I wrote to Mr. Parnaby at 

 Keswick, and purchased some great lake trout eggs, which he 

 had imported from Switzerland. The slate trays were ready by 

 the New Year, and, as I had no hatching-house, I placed two trays 

 in the 9-feet plank pond, and laid the eggs on the slate. They 

 were about a month from hatching when they arrived. I had not 

 thought of placing a screen in front of the spouts of the slate 



