106 CALIFORNIA PISH AND GAME. 



abounds. It is not sti'ietly characteristic of estuary growth, however, 

 as illustrated by fish taken at or near the mouth of Klamath River. 

 In the latter part of August, and probably much earlier, yearling 

 salmon appear in the estuary, where they linger and grow very rapidly. 

 Some specimens measuring 200 millimeters and looking much like min- 

 iature salmon from the sea were collected in September. A scale from 

 one of these is shown in figure 47. In this scale a nucleus, A, is appar- 

 ent, w^hich is surrounded by an area of wider circuli. From facts 

 learned from observation of these fish, this region is undoubtedly rep- 

 resentative of estuary growth, and a comparison of this with the area 

 A-B would scarcely lead to a similar interpretation for the latter. It 

 seems more probable that after being liberated this fish hastened on his 

 long journey to the sea, growing very little, if any, on the downward 

 passage. 



While in the sea during the second year, two checks in growth 

 occurred, due to what cause we have no means of knowing. Near the 

 end of the second year a check normally appears. This is represented 

 at D. Abundant material from Monterey Bay shows that this check 

 usually develops in the winter or early spring, not appearing in all 

 individuals at the same time. 



The intermediate checks offer nothing remarkable, as somewhat 

 similar characters may be easily found in any large assemblage of king 

 salmon scales. They might be passed over as indicating that some event 

 in the life of the fish, temporary scarcity of food, for example, had 

 served to interrupt or check its normal growth at a particular time. 

 But in this they deserve further consideration, as will appear. 



Of the twenty-three marked salmon which were recovered, no less 

 than seventeen possessed scales which in every essential detail were 

 like that illustrated in figure 43. That the nuclei should be much alike 

 occasions no surprise, for all were reared alike, and consequeutly envi- 

 ronmental conditions were similar for all while the nuclear growth pro- 

 gressed, but that this detailed resemblance should continue in such a 

 marked way through the second year is worthy of attention. 



Under an hypothesis that the growth of the fish is reflected by the 

 growth of the scale, and that growth is influenced by environment, the 

 assumption follows that all of these fish must have been in contact with 

 the same environmental conditions during the second year. It would 

 appear not at all improbable that they schooled together. This suggests 

 the possibility that associations formed in the stream may continue in 

 a large measure throughout life in the sea. The four-year fish of this 

 marking, if any are caught, will furnish additional data of interest in 

 this connection. They will also bring a record of the third year, which 

 in these grilse is largely effaced. 



Scales of the remaining marked fish differ in a minor degree only 

 from the others by having a more or less well-defined check about half 

 way between those marked B and C in figure 43. 



As 250,000 fish were liberated, of which 25,000 were marked, the 

 return of ten unmarked individuals with every marked one might 

 be expected. Unfortunately, scales were preserved from very few 

 unmarked grilse while the marked ones w^ere being taken. However, 

 among those that were preserved are two which show the same charac- 

 teristic scale structure as the marked ones. A photomicrograph of one 



