There is one wholesale method of destruction which particularly affects salmon, which cannot be passed over. This is done by almost innumerable nets, and is usually practised at the mouths of rivers and generally without the slightest regard to the economy of the fish supply. And it has been found that as salmon and the means of transit increase, so does the number of destructive nets. Theoretically, legislation is levelled against this wanton destruction, but practically the law is a dead letter. At every tide, in certain seasons, hundreds of thousands of salmon-fry and smolts are sacrificed; and in a certain firth it is recorded how a fisherman in his nets walked, in many places, knee deep in dead smolts, and that the ground for a considerable distance was silvered with their scales. Under these circumstances the samlets sometimes accumulate to such an extent that they have to be carted on to the nearest land and used as manure. This waste of valuable fish food is so great that it can hardly be reckoned, and in future years must tell greatly upon the British yield of salmon. Mill-wheels[5] and hatches, too, are often great sources of destruction. [5] "In this neighbourhood I escaped, by pure good fortune, a danger that I afterwards learnt proved fatal to thousands--nay, tens of thousands--of my young companions. The stream had apparently divided, and whilst I followed the course of the right-hand one, the greater number passed down the wider but less rapid left-hand division. Here they speedily encountered a terrific mill-wheel, and, dashing on one side, they found their progress stopped by a small net, which being placed under them, they were landed literally by bushels. My informant, who escaped by passing under the mill-wheel at the imminent risk of being crushed to death, assured me that the bodies of our unlucky brethren were used as manure! And, degrading as the suggestion is, it seems not impossible, for the numbers taken could not be sold or used for food."--_The Autobiography of a Salmon._