10,000,000 in the Severn, it is estimated that between 50 and 75 per cent. of the Alevins pass into the Fry stage, thus bringing the quantity to about 700,000. "In the Fry and Samlet stage the mortality increases to what degree is mere guess, as there is little, if any, evidence; but the mortality must be 50 per cent., so that there would be 350,000 Smolts. Among the Smolts there is also a very high rate of mortality, say, at least 75 per cent., so that the fish that reach the Grilse stage would be something like 40,000 out of 10,000,000 ova, or 4000 per million, about 4 per cent."[1] In Kamschatka the Salmon have probably fewer enemies, as the rivers literally swarm with them; and Guillemard refers to one "little village" where, during the season, "20,000 fish would be no uncommon catch for a single day."[2] The same author describes his impressions when standing on the banks of a little branch of the Avatcha River, not more than eighteen inches deep. "Hundreds were in sight, absolutely touching one another, and, as we crossed the river, our horses nearly stepped upon them. Their back-fins were visible as far as we could see the stream, and aground and gasping in the shallows, and lying dead or dying upon the banks, were hundreds more.... The millions of fish that are caught, and form the food throughout the year of almost every living creature in the country, are, however, as nothing compared with the countless myriads that perish naturally."[3] Krashenniker, writing more than one hundred years ago, says:—"The fish come from the sea in such numbers that they stop the course of the rivers, and cause them to overflow the banks, and when the waters fall there remains a surprising quantity of dead fish upon the shore, which produces an intolerable stink." Guillemard considers that the vast majority—practically all, in fact—ascend the streams to spawn, and, having once done so, die. In the case of some species every fish appears to perish; in others a few get back to the sea.[4] Besides other enemies, when Salmon are abundant and lie close a dreaded disease makes its appearance. This shows as a white fungus about the head and shoulders, and gradually spreads until the fish sickens and dies.[5] The female
