280 SCIENCE SKETCHES. 



or Salmo gairdneri. This gairdneri we regard as a 

 species different from Salmo myldss. Its mouth is 

 smaller, and the sides more red. But the fading of 

 the cut-throat mark is the chief sign by which we 

 may know it from its ancestors; and this must 

 have passed away by gentle stages, for in the Kern 

 trout and the Shasta trout its descendants, if this 

 supposition is true there are still traces of the red 

 dash, which the common Steel-head no longer 

 shows. 



Let us suppose that the descendants of the 

 gibbsii entered the Lower Columbia when the 

 blockade at the Cascades was worn through. 

 They must have found the sea congenial, for with 

 the gairdneri we find more of the migrating habit 

 than in any of the mykiss forms. Trout who go 

 to the sea must some time come back to the 

 mountains, for all trout and salmon cast their eggs. 

 in the gravel of fresh-water brooks or cold lakes. 

 Migrating trout go up all the streams from Point 

 Concepcion to Vancouver Island. Ocean feeding 

 makes large trout. Ten pounds is not uncommon, 

 and they have been known to run as high as thirty. 

 These sea-run fishes are known as Steel-heads, or 

 Salmon Trout, and are often taken for salmon. 

 They are trout, nevertheless, not salmon at all. 

 The name Steel-head, being used for no other fish, 

 is well applied to them. 



They are a good and gamy fish in their season, 

 but are not always so when taken in the rivers. 

 The Steel-head spawns in the winter, later than the 

 salmon, and when taken as spent fish in February 

 or March, it is often coarse and poor. It then 



