THE NEW AKT OF BREEDING FISH. 121 



three, or four days, and then the rivers — I mean 

 good ones — abound with fresh-run fish. 



A fresh-run fish is known by the brightness of 

 its scales, 'by its corpulency, the whiteness and soft- 

 ness of its fins, by the shallow forking of the tail, 

 and by parasitical insects .adhering to it. These in- 

 sects, or vermin, disappear, it is stated, from the 

 sides and belly of the salmon after it has been in 

 fresh water forty-eight hours. Some persons argue 

 that salmon return to fresh water to get rid of these 

 sea parasites. Not so ; if they did, they would, as 

 soon as the insects disappeared, emigrate again to 

 sea. This they never do until they have been many 

 weeks in fresh water. 



Salmon, after its first year, never grows in length 

 or bulk in fresh water. After its firsj; immigration 

 from the sea as a grilse, it diminishes in muscle, 

 fibre, and fat, every day it remains in fi:esh water. 

 Its fins become black and strongly elastic^ and its gill- 

 covers and back assume the same color. It is then 

 called a "black" fish, in contradistinction to the 

 bright, clean, fresh-run (just arrived from sea) fish. 

 It does not, until within a very few weeks of spawn- 

 ing, lose strength in fresh water. It is more active 

 than the fresh-run fish, has greater propelling power 

 by means of fins hardened by fresh water. Salt 

 water so softens the fins of salmon as to render them 

 feeble propellers. We do not know how far sea- 

 wards salmon travel to feed. I should say not far 

 beyond the mouths of estuaries or the shores of 



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