2 



BULLETIN OF THE BUREAU OF FISHERIES 



five distinct species of wide distribution throughout Alaska, and that each of these 

 species has an independent, self-perpetuating colony in each of the streams that 

 it inhabits. Each colony forms a self-contained unit, the members of which 

 consistently interbreed, their progeny returning to their native stream at sexual 

 maturity. Such a colony secures no recruits from adjacent streams; its maintenance 

 at a high stage of abundance depends on there being provided each year, from its 

 own members, an adequate spawning reserve, which shall successfully deposit their 

 eggs in the river gravels. This necessity defines in large measure the regulatory 

 duties of the Bureau of Fisheries. It must counteract the destructive agency of an 

 unrestricted fishery by adopting and enforcing such regulations, locally applicable 

 to the different fishing districts, as will insure year after year adequate spawning 

 in each of the multitudinous streams throughout the vast extent of Alaska. The 

 magnitude of this problem becomes at once apparent, but its almost incredible 

 difficulties are known only to those intrusted with the administration of these fisheries. 



In the first place it must be ascertained whether depletion of a given salmon 

 run has occurred, and if so, to what extent. With adequate and reliable statistics, 

 extending over a sufficient period of time, this can be done. Annual fluctuations 

 in the magnitude of the runs, due to natural causes, can be recognized and evaluated 

 and a trend established that will measure the declining supply. Usually the salmon 

 statistics of the past have been inadequate and more or less untrustworthy, but such 

 as they are they form our only basis for establishing the fact of depletion and its 

 extent. In cases of pronounced depletion, however, such as unfortunately exists 

 in many localities, even the rudest statistics are sufficient to demonstrate its existence. 



It remains, then, to apply the remedy, and the question at once has arisen of 

 how extensive a spawning reserve must be provided to check depletion and increase 

 the size of the colony. In all fishery investigations in which conservation of a 

 threatened supply has been the principal aim, the ideal has been properly emphasized 

 to spare for commercial use all fish not needed to maintain the fish population at a 

 high level of abundance. It is a generally accepted motto that we limit our spawning 

 reserves to the lowest numbers consistent with safety, sparing every fish that can 

 be spared for the world markets and for human consumption. But at the time the 

 responsibility for the salmon fisheries of Alaska devolved on the Secretary of Com- 

 merce and the Bureau of Fisheries, we were without definite information concerning 

 the number of spawning salmon necessary to produce a run of a given size. It was 

 not even known, with regard to any stream, what proportion of its run had con- 

 stituted its actual spawning reserve in any year, whether adequate or inadequate. 

 Such statistics as we had dealt invariably with the portion of the run that had been 

 captured for commercial purposes, never with that moiety that had escaped the 

 fishermen and formed the basis for expectation of future runs. 



In default of this essential knowledge, which it requires years of investigation 

 to obtain, it may be asked what in the meantime has formed the basis of the bureau's 

 activities in protecting the various runs. The answer is, the method of trial and error. 

 When it is believed that a given district is threatened with overfishing, regulations 

 are enforced which will diminish the commercial take of fish and increase the size 

 of the spawning reserve, and the severity of the restrictions is planned to bear a direct 

 relation to the seriousness of the depletion. In such cases it is not known what 



