X REPORT OF THE COMMISSIONER OF FISHERIES 



water, due, perhaps, to the increasing amount of sewage entering 

 the Mississi])pi I\i\er from the cities located just above P'airport. 

 If this is true, it may be expected tliat increased difficult}' will be 

 ex]>erienced in handling mussels at this station. 



ALASKA CLAMS 



The investigation of the clams in tiie region of Cordova and Cook 

 Inlet, Alaska, begun in the latter part of the fiscal year 10:^;), was 

 continued during the summer of li)'2H. Data were ()l)tained for the 

 determination of the age, growth, and size at sexual nmturity, and the 

 date of the breeding season. Subsequently data for comparison were 

 obtained from the Washington coast. Among other interesting facts 

 it has been shown that the growth of clams on the Washington coast 

 is much more rapid than in Alaska and that a marketable size is 

 reached in one-half to two-thirds the time. A preliminary survey 

 of the density of population on the beds in the older regions and 

 their history indicates that these have about reached their full com- 

 mercial development, and that more intensive fishing is imwise. If, 

 however, the intensity of the fishing is wisely regulated and a breed- 

 ing reserve assured by a proper size limit, there is no reason why 

 clam canning should not be a permanent and valuable industry on 

 many Alaskan beaches. 



There has been a marked development of the clam canning indus- 

 try of Alaska, the pack in 192o amounting to TT.^^-i cases with a 

 value of $541,139. Because of this development and the slow rate 

 of growth of clams in the territory, it is important that we guard 

 against overexploitation. 



INVESTIGATIOXS RELATING TO FISH CULTURE 



The importance of fish culture in the husbandry of our fisheries 

 lies primarily in the increased protection of the eggs and young. 

 In a state of nature the mortality during the early stages is extremely 

 high, as it is among all animals that give little or no care to their 

 young. By protecting the eggs and young from unfavorable en- 

 vironmental conditions and enemies a nuich larger percentage may 

 be carried through this critical period in their life history. Present 

 procedures in fish culture are largely empirical and are based upon 

 the practical ex])erience of fish-culturists. With an increased knowl- 

 edge, gained through scientific researches, of the life histories and 

 ecological relations of the various fishes and of their physiology and 

 pathology, the art of fish culture will douljtless make rai)id advances. 

 It is one of the most important functions of the division of inquiry 

 to make the necessary investigations into the physiology and pathol- 

 ogy of fishes which are required for the proper regulation of hatchery 

 procedure. 



A number of the researches mentioned above bear directly upon 

 fish-cultural problems. The marking experiments conducted on the 

 Columbia River were designed ]jrimarily to test the relative efficiency' 

 of various practices, ])articularly as to the length of time the young 

 salmcm should be retained l)efore planting, the relative influence of 

 heredity and environment in producing fish of high quality, and the 



