THE SPAWNING PERIOD i6i 



the salmon though not often with unimpeachable accuracy. I think the 

 best description of the process which I have read is contained in Mr. 

 A. H. Chaytor's " Letters to a Salmon Fisher's Sons," one of the best 

 books on salmon angling which has been published for many years. 

 At any rate sea-trout go through much the same procedure. The 

 gravel they select is, however, of finer quality than that in which salmon 

 prefer to spawn, the difference perhaps being fairly represented by 

 mixed gravel, the stones of which, in the sea-trout's case, vary from the 

 size of a hazel-nut to ordinary road metal, and, in the salmon's case, 

 from ordinary road metal to the size of a brick. Objects under water 

 naturally lose much of their specific gravity, but it is surprising notwith- 

 standing how large are the stones which the fish are able to displace. 



Having selected a spot for the proposed redd the female sea-trout 

 throws herself on her side and, with a quick spasmodic action of the 

 body, rapidly repeated several times, works a hollow in the gravel into 

 which the ova as they are extruded, being heavier bulk for bulk than 

 water, are carried by the flow of the stream. Working her way slowly 

 upstream she covers the eggs thus deposited with the freshly loosened 

 gravel. The male fish for his part is closely in attendance shedding 

 his milt freely, and this, even when, as it must be, greatly diluted by the 

 stream, is able to fertilise all the eggs with which it comes in contact. 

 Yet the artificial propagation of salmon and sea-trout has shown that all 

 the ova at any time are not necessarily fertilised, and it is reasonable to 

 suppose that even when male fish are not scarce — as they sometimes 

 are — some of the ova shed under natural conditions escape fertilisation. 

 It is impossible to estimate the numbers of these, and probably the net 

 total fertilised varies enormously according as the spawning conditions 

 are favourable or the reverse. At all events any unfertilised eggs 

 ultimately become a dead white and soon perish. 



On 28th October, 1913, I had a specially favourable opportunity of 

 seeing the sea-trout spawn in the Finlas Water, one of the tributary 



