ATKINS THE SALMON AND ITS ARTIFICIAL CULTURE. 333 



steady depreciation in size. There are comparatively few salmon of ten 

 to thirteen pounds weight caught in April and early May ; but this is the 

 ruling size of those coming late in Juue and in July, constituting what 

 are called the " school-salmon,-' from their apparent tendency to move 

 in considerable bodies. 



Of the sexes, there appears to be a greater proportion of females in 

 the early part than in the late part of the season ; but the similarity 

 of the sexes among the early salmon is so great as to generally prevent 

 their separation by external characteristics. By the end of Juue the 

 males have assumed so much of the peculiar characteristics that mark 

 them at the breediug-season that the sexes can be distinguished with 

 tolerable certainty. In the month of Juue the females are, in the Pe- 

 nobscot River, largely in excess of the males. 



In approaching the rivers, salmon swim near the surface, and are not 

 inclined to leap into the air. In the early part of the season they appear 

 to move at a greater distance from the shores than they do afterward, 

 so that they frequently pass all the pounds and weirs of the estuaries 

 aud are first taken in the rivers, where the contracted breadth of the 

 water or some other cause induces them to run near shore. At the 

 height of the salmon season, however, they appear to be coasting along 

 very near the shore, so that where two weirs are built on the same 

 hedge that near shore takes more salmon than the other. 



It seems that the main body of the salmon proceeds at once to the 



vicinity of the spawning- ground. In general, this may be said to be on 



the headwaters of the large rivers, but in the middle course of such as 



the Denny's. The earliest reach the limits of their upward migration 



on the Penobscot before mid-summer. 



(7 c.) Changes in the appearance of salmon ivhile in fresh ivater. — 

 From that time until the spawning-season, they lie in deep, quiet 

 pools, and frequently, no doubt, in the lakes traversed by the rivers. 

 Meanwhile, a complete change takes place in their appearance. Both 

 sexes lose the brightness of their silvery sides. The female becomes 

 dark-colored, tinged to a slight extent with some shade of red or orange, 

 and with irregular spots of the same color. All parts of the body fail 

 away in fles:h, except the abdomen, and that becomes distended with 

 the growing spawn. The change in the males is more marked. They 

 become very thin from side to side, so that the widest part is near the 

 gills. At the same time their depth increases, and the head lengthens- 

 The jaws become curved, and the lower one is tipped by a large hook 

 that shuts into a cavity in the roof of the mouth; sometimes, indeed 

 making itself a hole quite through the upper jaw, and projecting above 

 The curvature of the jaws is so great that they do not close except a 

 the tips. The fins become very thick and fleshy, the adipose dorsa 

 greatly enlarged, and the whole body covered by a thick mucous coat 



