1 2 6 PROBLEMS IN WILD LIFE CONSERVATION 



headquarters at Beaufort, N. C, Great Lakes, Ann Arbor, 

 Mich., Interior Waters, Columbia, Mo., and Pacific Coast- 

 Alaska, with headquarters at Seattle, Washington. The 

 remaining five sections deal with aquiculture, screen and 

 ladder, western trout, and shell fisheries investigations, be- 

 sides a section devoted to ichthyological studies. 



The functions of this division, as implied by its name, are 

 biological research in aquatic animals. As has been pointed 

 out, research is, and rightly should be, one of the chief 

 functions of the federal government in relation to wild-life 

 conservation. In the early days of the Fish Commission 

 the stress in research was upon systematic ichthyology but 

 since 1900 the policy of the bureau has undergone a gradual 

 change and at the present time the major studies of the 

 bureau are upon physiology, embryology, and the natural 

 history of fish. 



Studies in the temperature, currents, and chemical com- 

 position of sea water, its oxygen content, acidity, salinity, 

 etc., all have ultimate bearing on fishery problems, some of 

 them surprisingly direct. Each of these factors influences 

 the kind and quantity of the small floating organism in the 

 surface of the waters known collectively as plankton, upon 

 which fish feed. Through a study of the currents, spawning 

 grounds have been discovered, their extent charted, the dura- 

 tion of larval life and the distances eggs and larvae are car- 

 ried has been worked out. 



Interesting as abstract facts may be, the fisherman is con- 

 cerned in only one problem and that is the production of 

 bigger and better fish. In other words, the most immediate 

 practical contributions of fishery science are the quantita- 

 tive studies of fish populations. It is the three factors, birth 

 rate, death rate, and migrations that determine the local 

 abundance of any species of fish. To be able to forecast 

 the abundance of fish in a certain locality, and to determine 



