THE LIFE OF THE SALMON.* THIS is the most important
contribution to the vast litera- ture of the salmon that has appeared for some time. Mr. W. L. Calderwood, as Inspector of Salmon Fisheries for Scotland, can speak with experience and authority. He is also imbued with the scientific spirit which only values well-ascertained facts. By these, and not by the theories of anglers or the dogmas laid down by owners of nets, has our knowledge of the habits of the salmon been increased. A great number of interesting observations and experiments are recorded in this volume. At the same time, it is well to begin, as Mr. Calderwood does, by admitting that we still do not know much about the life of the salmon. Indeed, it is but little more than fifty years ago that the parr was found to be a young fish and not a separate species. The difficulties of observing the salmon are, of course, enormously increased by the migratory habit which takes it to the sea, and so removes it from our sphere of knowledge. It is worth noting by the way that Mr. Calderwood regards the salmon as a marine fish which has acquired the habit of spawning in rivers. But the difficulty of following the salmon on its excursions into salt water has been to some extent got over by marking fish and watching for their recapture. Much informa- tion has been obtained by this method. Marking operations are being carried on upon a large scale, and in 1905 no less than six thousand five hundred smolts were marked in the
• The Life of the Salmon : wit h Reference more especially to the Fish in Scotland. By W. L. Calderwood, F.E.S.E. London : Edward Arnold. [7a. 6d. net.] Tay with a little silver loop through the dorsal fin. The very instructive results of this experiment are set out in Mr. Calderwood's second chapter, which seems to show that it is the habit of many individuals to remain in the sea beyond the grilse stage. These are first recaptured in the shape of small spring fish. On the question of salmon feeding or fasting in fresh water Mr. Calderwood, of course, holds that they do not " feed " in the sense of eating and nourishing their tissues. No one who has examined the evidence can hold a contrary view. At the same time, this does not involve a denial of the undoubted fact (as tl,e ordinary man, heated by discussion, often appears to thin s) that salmon take into their mouths so-called flies, pray, us, minnows, and other edible lures. The nature of the food of the salmon in the sea and the enormous amount consumed have now been fairly well ascertained. But Mr. Calderwood maintains that the entrance of the salmon into fresh water is not wholly explained by a condition of satiety. A valuable and quite modern dis- covery (which is elucidated by plates in the fourth chapter of Mr. Calderwood's book) has taught us to read the age and life-history of a fish from its scales. The periods of feeding and non-feeding and of spawning are disclosed by a study of the rings of the scales under a microscope. It is surprising to find that many spring fish of twenty pounds from the Tay have never spawned. Experi- ments have also shown that the sea-lice, which are sought for by the angler on fresh-run fish, may remain on for four or five days. An appendix gives some old records of salmon- marking dating back to 1823. It is, of course, only within the last few years that tests have been applied on a really trustworthy scale. Yet Izaak Walton mentions experiments of tying ribbons to the tails of young salmon to see whether they returned to the same rivers.
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