SPAWNIN"G HABITS OF THE SALMOK. 471 



and July, though some come as early as April, and in the Miramichi from the middle of June to 

 October. I can only account for this seeming paradox by the theory that, while Salmon are not 

 harmed by extreme variation of temperature, they may be averse to sudden changes, and though 

 strongly impelled to seek the spawning grounds are prevented by the cold. I have ascertained 

 that the cod possess very little animal warmth. The temjjerature of the blood of a number of 

 individuals caught in twenty -five fathoms of water was 47° Fahrenheit, precisely that of the water 

 at the bottom whence they were lifted. Mackerel swimming at the surface registered 59° or 60°, 

 while the temperature of the water was 58°, thus indicating that they possess a trifling amount of 

 animal heat. The Salmon unquestionably changes its temperature with that of the surrounding 

 water in much the same way, and if, as is probable, rivers rising in the mountains are colder in 

 early spring than the ocean strata frequented by the Salmon, here is a possible solution of the 

 problem. It is stated that in the English rivers, which are always open, there are no regular 

 seasons of ascent, the flsh constantly passing in and out; indeed, Mr. Atkins thinks it pretty 

 certain that large Salmon in prime condition are running into the Penobscot from the sea every 

 month in the year. It is likely, also, that the warmth of the rivers is an important factor in accel- 

 erating the vegetative growth of the eggs in the ovaries of the mother flsh. 



The movements of the Salmon are not so intimately related to the temperature of the water 

 as those of many other species. They are not sensitive to sudden changes, and are capable of 

 enduring a range of at least forty-five degrees. In this they resemble less the migratory fishes 

 than the permanent residents of our fresh waters; indeed, it is quite allowable to speak of them 

 as resident, for a large proportion of the whole colony belonging in one river may be found in it at 

 any season. This proportion cannot fall much below two-thirds, if we consider that the fish less 

 than a year old would make up at least half its number, and that the breeding flsh are in the 

 rivers six or seven months after the breeding. The breeding flsh remain during the season of 

 greatest heat and greatest cold, though their stay after they have deposited their eggs is no 

 doubt chiefly because their vitality is diminished and their circulation retarded by the falling tem- 

 perature, depriving them alike of the craving for food and the power to seek it. Those which 

 spawn early are believed to return at once to the sea; the more tardy ones often remain all 

 winter, and are carried out by the spring freshets. Salmon eggs are not injured by freezing, and 

 the flsh are unquestionably quite as hardy. English flsh-culturists claim that their Salmon will not 

 thrive where the water is warmer than 60°, or at most 05° in the summer, but Mr. Atkins kept flsh 

 in his ponds at Bucksport, Maine, with the water at the bottom as warm as 74° at midday, the 

 means of bottom and surface temperature for June, July, August, September, and October, 1872, 

 being 6O0.6, 65o.9, 69o.8, 59°, 60o.3, and 72°.9, 73°.l, 73o.G, 620.2, 54°.3, respectively. In the Gasp6 

 salmon streams, where the flsh are in the perfection of activity, the temperature of the pools in 

 July ranges from 40J° to 59°. 



EJiLTS. — At the approach of the spawning season their trim shapes and bright colors disappear. 

 They grow lank and misshapen, the flns grow thick and fleshy, and the skin, which becomes thick 

 and slimy, is blotched and mottled with brown, green or blue, and vermilion or scarlet. These 

 changes are chiefly apparent in the males, whose jaws now become curved so that they touch only 

 at the tips, the lower one developing a large, jiowerful hook, which is his weapon in the savage 

 combats with his rivals in which he at this period engages. When in this condition, and after 

 spawning, when they retrace their course to the sea, they are known as "Kelts." 



Having entered a river, they press on to its headwaters, where the earliest of them arrive two 

 or three months before spawning time. As soon as the water is cool enough they proceed to deposit 

 their eggs, in deep furrows which they plow up in the sandy or gravelly bottom of the stream, 



