[mcmurrich] pacific COAST SALMON 31 



the conclusion being that the fish, when caught, was in its fifth year. 

 There is no indication on the scale that this fish had ever spawned; it 

 had apparently merely postponed its return to the spawning ground 

 for one year beyond the typical four. 



In the second fish, however, a spawning scar was distinctly visible 

 upon the scales. The fish measured only 87.5 cm., a length that would 

 suggest its reference to the second group, but an examination of its 

 scales showed that it was a five-year-old fish, its small size being proba- 

 bly due to the fact that i; had already spawned once. The scales (Fig. 5) 

 show the usual fresh-water area, and this is succeeded by the sea 

 area in which two check bands are quite evident, indicating the third 

 and fourth winters of the fish's life. The band representing the fourth 

 winter is followed by a small number of widely separated lines repre- 

 senting the first part of the fourth summer and then follows a distinct 

 scar, which may be traced around the entire scale, even upon the exposed 

 portion. From analogy with what is known as to the significance of 

 such markings on the scales of Atlantic Salmon this must be interpreted 

 as a spawning scar, and it was evidently formed in the latter part of 

 the summer and the autumn of the fourth year. The scar is followed 

 by a very narrow check band not evident in all parts of the scale, but 

 quite distinct toward the exposed portion, and this, which may be taken 

 to represent the fifth winter, is followed by a number of lines representing 

 the fifth summer. 



The life-history of this fish, as revealed by its scale markings, may 

 be summarized as follows. Assuming that the Steelhead spawn usually 

 in the late autumn and adopting the terminology applied to the various 

 stages of the Atlantic Salmon, the ovum from which this fish developed 

 was spawned in the autumn of 1907, and the young fish remained in 

 fresh water until the spring of 1909, entering upon what corresponds 

 to the parr stage in the autumn of 1908. In the spring of 1909 it 

 assumed the smolt form and descended to the sea, where it passed the 

 winter of that year and was a grilse in the summer of 1910. It remained 

 "n the sea throughout the following winter and in the late summer 

 of 1911 returned to the spawning grounds as a four-year-old fish. 

 It spawned in the avitumn of that year and returned to the sea as a 

 kelt in the early winter. During the remainder of that winter and a 

 portion of the summer of 1912 it remained in the sea,and in that summer, 

 when it was a five year-old fish, it was captured, probably on its way 

 Î ack to the fresh- water to spawn for the second time. 



