THE SALMON FAMILY. 901 



species. These Salmon-pests are ever on the watch whilst 

 Salmon are depositing their ova, and are only kept away 

 from the spawning-beds or trenches by fierce attacks and 

 rapid charges made on them by male and female Salmon, 

 both whilst they are preparing to spawn, and are, at least one 

 of them, actually engaged in doing so. However, as long as 

 a spawning Salmon is in its bed, or nest, laying ova or 

 impregnating it, no Trout will venture to come near the 

 excavation. It is only when spawning fish drop down the 

 stream, to gather vigor for the formation of another nest, or 

 link of the bed above that already excavated, and in which 

 uncovered ova are deposited, that Trout dart towards the bed 

 and devour the spawn. The falling down stream for a short 

 time and short distance on the part of Salmon is of twofold 

 necessity : first, to gain renewed strength by temporary cessa- 

 tion from labor ; and secondly, to get space enough to ' take 

 a run,' if I may use a jumper's phrase, in order to be able to 

 dart their heads with greater force and effect into the sand 

 and gravel for the formation of a new nest, or link in the bed- 

 trench. The water-ousel is also a sad destroyer of Salmon 

 ova. It watches their emission by the spawning Salmon, 

 then dives into the water, and descending to the bottom, runs 

 along it to the spawning-bed, out of which it extracts a large 

 quantity of spawn, and would steal more did not the procrea- 

 ting fish see it and drive it away. The spawn once fairly 

 covered in, neither Trout, nor water-ousel, nor any other fish 

 or bird can injure it. The supposition that Eels burrow into 

 Salmon-beds and feed upon the spawn beneath, is erroneous. 

 "It is alleged that alluvial deposits frequently settle upon 

 and cover the beds, thereby destroying the ova addling 

 them, in fine, by preventing the chemical action necessary 

 for their incubation from reaching them. Such occurrences 

 can very rarely, if ever, take place in the spots Salmon select 



