THE BREEDING SALMON. 5° 7 



closely those of the Ehinc according to a recent and very thorough 

 investigation* by the Fishery Board of that country. The salmon in 

 the rivers of Alaska, however, acccording to the report upon the subject 

 by the United States Fish Commission,! exhibit certain differences 

 which are significant of the physiological purpose of the habits and 

 tissue changes in the breeding salmon. The principal runs of these 

 salmon from the sea to their spawning grounds occur after the ice 

 has broken up, and through a great part of the brief Alaskan summer. 

 The number of fish swimming up stream at such times is so enormous 

 that at places the current is almost choked by the struggling mass. A 

 man wading through the shallows can kick the salmon out upon the 

 shore by scores. The distances which these salmon must ascend is 

 much less than in the Ehine — often only a few miles. Yet the diffi- 

 culties overcome in struggling over shoals, leaping up waterfalls, and 

 in attempting to pass the barriers of heavy timber recently erected 

 by the canneries, are enormous. During this journey the males develop 

 formidable looking beaks, and the genitalia grow to a size even greater 

 perhaps than do those of the Ehine salmon — although exact figures 

 are not available. At the same time both sexes become emaciated to 

 an extreme degree, all the muscles and organs of the body being drawn 

 upon apparently to supply material to the genitalia. It is certain that 

 the fish do not feed after leaving salt water; indeed it is doubtful 

 whether the beaks of the males would allow it even if they wished. 

 But all the Alaska salmon — of which there are several species — differ 

 from those of the Ehine in one respect. Xo adult salmon has ever 

 been seen swimming down stream, and those which are washed down 

 by the current die after reaching salt water. The greater number 

 after spawning remain, near the spot where the eggs are deposited, 

 driving off intruding salmon that would disturb their nests, and maraud- 

 ing trout that would devour their eggs, until overcome by starvation 

 and the exhaustion entailed by their journey and tissue changes, they 

 die. They afford a striking example certainly of the sacrifice of the 

 individual to the good — or the only 'good' that Nature seems to 

 recognize — the perpetuation of the species; and this example is none 

 the less striking because it can scarcely be supposed that these fish 

 have any consciousness of the object for which they thus struggle 

 and die. 



The reason for these habits and tissue changes is probably to be 

 found in. the advantages which they confer upon the salmon in the 



* Report of the Scottish Fishery Board on the Investigations on the Life 

 History of the Salmon in Fresh Water, from the Research Laboratory of the 

 Royal College of Physicians of Edinburgh; Edited by D. Noel Paton, M.D., 

 1898. 



t Bulletin of the V. 8. Fish Commission, Volume XVIIL, 1898. 



