278 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



necessary to obtain accurate estimates of the area 

 occupied in each depth zone to permit proper 

 weighting of the index for eacli depth zone accord- 

 ing to the proportion of the population represented. 

 This areal distribution cannot be obtained from 

 the records of the commercial fishery. Therefore, 

 final abundance indexes depend upon surveys of 

 distribution by a research vessel. Such data 

 have been obtained for recent years and are in 

 process of analysis. 



LITERATURE CITED 



Herrincton, William C. 



1948. Limiting factors for fish populations; some theories 

 and an example. No. 9 in A symposium on fi.sh popu- 

 lations. Yale Univ.. Bull. Bingham Ocean. Coll., 

 vol. 11, art. 4, pp. 229-283. 

 RorN.SEFELL, George A. 



1948. Development of fishery statistics in the North 

 Atlantic. U. S. Department of the Interior, Fish and 

 Wildlife Service, Spec. Sci. Rept. 47. 27 pp. 



SnEUECOR, CiEORfiE W. 



1940. Statistical methods. Iowa State College, Ames, 

 Iowa. 422 pp. 



U- S. GOVERNMENT PRrNTING OFFICE 1957 O — 406253 



