120 FISH AND GAME COMMISSION 



Aftci' entering the soa, they may wander long distances from the mouth of 

 their native stream. Klamath River fish, for example, migrate southward to 

 Monterey Bay, and Sacramento liiver fish move a considerable distance north- 

 ward as well as southward. 



Individual fish at times remain closely associated for a year or more while 

 at sea, possibly in the same school. 



Adult fish return upon their nuptial migration to the stream from which 

 they enter tlie ocean, regardless of where the eggs were taken. 



When yearlings are introduced into, and given a sufiicient exposure to the 

 waters of a particular tributary, they tend on their return migration to seek 

 out and enter that tributary, while under less favorable conditions they may 

 scatter to a considerable extent. This is Avhat might be expected in nature, 

 the homing instinct preserving the exact geographic distribution of the species, 

 while the tendency of individuals to straggle pro\ndes a means for the spread 

 of the species as opportunity presents. 



Studies relating to the life history of the silver salmon were* begun by the 

 introduction of considerable numbers of marked and unmarked fish in 

 Boulder Creek and the main channel of San Lorenzo River. Eggs were 

 brought from Redwood Creek, in the northern part of the state, placed in the 

 hatchei-y at Boulder Creek where, under the care of John Marshall, foreman 

 of the hatchery, they were kept under observation until the ensuing fish were 

 liberated. Silver salmon reared from the eggs of native fish, by C. L. Frame, 

 foreman of Big Creek hatcherj', were marked and introduced into Scott and 

 Waddell creeks, and the Pajaro River. 



It is expected that the returning adult fish will furnish us with a verifica- 

 tion of age determinations which have been arrived at from an examination 

 of the scales of adult fish. Also, some notion may be gained as to whether it 

 is feasible to artificially propagate the species in these streams, and what is 

 the best time and place for liberating the young. 



Since the inauguration of an efiicient statistical system by the division, the 

 rapid depletion of the salmon fishery has been made apparent. In addition 

 to the ordinary and easily observable phenomena, such as the progressive 

 annual reduction of the catch, the constantly increasing effort expended in 

 making it, the discovery and development of new fishing grounds, the increase 

 of the price paid for the fish, etc., another aspect of depletion, which is less 

 familiar, has appeared. This is an enormous increase in the relative nuniber of 

 two- and three-year fish in the catch, over what may be regarded as the 

 normal of preceding years. 



During the season of 1928 it became evident that a considerably larger 

 pi'oportion of small fish Avere being brought to the markets from sea trolling 

 than ever before. As usual, the fishermen attempted to account for this in 

 various ways, but a small sampling of the Monterey catch seemed to indicate 

 that a large proportion of immature fish was being taken. Of 3S3 represen- 

 tative samples, 50 per cent were in the second year of growth, and 31 per cent 

 were in the tliird year. In 1029, a careful survey of the situation was made. 

 At ^lonterey samples of the catch to the number of 2S00 were examined from 

 April 23d to July 29th. Of these, about 17 per cent were in the second year 

 of growth, and 02 per cent in the third year. Approximately SO per cent of 

 the catch consisted of two- and three-year fish. 



Now we fortunately have at hand an age determination of large and repre- 

 sentative samples of the Monterey catch for the years 1919, 1920, and 1921, 

 when the relative number of two- and three-year fish did not go over 40 i>er 

 cent. Unless an unsound inference is being made, it would seem that the 

 supply of old fish is greatly reduced, and that the Monterey Bay catch is 

 considerably reducing the population of young fish which should be left to 

 mature in the near future. 



It is intended now to make an investigation of the seaward migrations of the 

 young fish in Klamath River, to make an examination of the spawning beds 

 in a restricted area of the basin to attempt an estimate of the relative produc- 

 tion of natural propagation in a resti-icted area, to get some definite idea of 

 damage done by irrigation, etc. As a part of this program, a trap has been 

 installed at the mouth of Shasta River, where an observer may make a count 

 of the spawning fish which enter the river. No artificially reared fish will 

 be placed in the river, therefore in the course of time a fairly accurate estimate 

 of the results of natural propagation may be made, and some of the diflieulties 

 which attend it may be observed. 



