256 FLY FISHING AND SPINNING 



to find a mate have proved abortive, may with reason be 

 most naturally expected to be among those which will be 

 impelled to revisit the river, and whose marking will, there- 

 fore, show a second or even a third period of scale de- 

 crepitation. 



It is rarely the case that a male fish is found in a fresh 

 run condition in a river, showing on its scales the decrepita- 

 tion marks of a former visit to fresh water. This means 

 that the male fish is generally successful in the attempt to 

 ascend a river, and once having achieved this the object 

 of its life it seldom, if ever again, even if it survives, 

 attempts a subsequent spawning visit. 



In this fact probably lies the explanation of much that 

 has hitherto been regarded a problematical, for it may be 

 that the male fish, physically stronger, and physically less 

 encumbered than the female fish, is able to attain the object 

 of its life by reaching the spawning beds in the upper waters 

 of its rivers ; whereas the late-running female fish, sexually 

 more delicate in its construction and encumbered by its 

 ova, is more liable to failure in its initial attempt, and con- 

 sequently carries on its scales the evidence of this failure 

 in the form of decrepitation marks. 



THE PHYSIOLOGICAL CHANGES IN THE CONDITION OF 



SALMON 



The alteration in the condition of the salmon is due in 

 the first place to the physiological influences of the genital 

 changes, and as a consequence, to the loss of nourishment 

 owing to non-feeding, and to the change from salt water 

 to tidal or fresh water. 



These three causes physiologically alter the condition of 

 the fish and its skin, and the scales which are held therein. 

 Attendant on this altered condition the annular markings 

 on the posterior portions of the scales may be entirely 



