970 U. S. BUREAU OF FISHERIES 
the Bureau of Foreign and Domestic Commerce, the Bureau of Sta- 
tistics, the Department of Commerce and Labor, and the Treasury 
Department. 
PRACTICES AND TERMS 
Certain practices and terms of importance used in the compilation 
of fishery statistics are explained below. 
Days absent —In computing ‘‘days absent” for vessels landing fares 
at the various ports, the day of departure and the day of arrival are 
included; thus a vessel leaving port on the 8th of the month and 
returning on the 15th of the month will be shown as being absent 
8 days. 
Operating units —Operating units as referred to in this document 
include persons engaged in the fisheries, and fishing craft and gear 
employed. 
Vessel.—The term ‘‘vessel” refers to a craft having a capacity of 
5 net tons or more. 
Boat—The term ‘‘boat”’ refers to a craft having a capacity of less 
than 5 net tons. 
Incidental catch—The term ‘incidental catch’’ refers to the catch 
of certain species by a type of gear which ordinarily does not capture 
such species. 
Percentages Percentages are usually shown as whole numbers. 
Fractions of percents are dropped if less than five-tenths, and the 
percentage is raised to the next higher integer if the fraction is greater 
than five-tenths. If the fraction is exactly five-tenths, the integer is 
raised or lowered to make it an even number. 
Converting.—Many of the figures shown in the statistical tables 
published herewith have been converted to thousands of pounds or 
dollars. In making these conversions the largest number from which 
a group of items is computed is raised or lowered to the nearest 
thousands place. If the number ends in an even 500, the thousands 
integer is raised or lowered to make it an even number. The indi- 
vidual items are changed to conform to the total thus obtained. 
Confidential data.—The statistical data collected by the Division are 
confidential and are not released except by approval of the Washington 
office. Statistics of production of wholesale and manufacturing firms 
are published only for commodities or geographical areas where the 
production of three or more concerns may be grouped. Every effort 
is made to publish only those figures which will not reveal individual 
enterprise. 
CONVERSION FACTORS 
It is the policy of the Bureau to show the detailed catch figures of 
all products in pounds for the sake of uniformity and for purposes of 
comparison. Following such a policy presents certain problems. In 
the case of fish there is little difficulty since in very rare instances are 
such products reported in units of measure other than pounds. For 
shellfish, however, the units of measure may be bushels, sacks, barrels, 
or thousands of shellfish, gallons of meats, ete. These many units 
make standardization difficult, but when coupled with the wide varia- 
tion in the requirements or definition of some of these units in the 
various States the problem becomes even more complex. 
All bivalve mollusks are reported in pounds of meats in the detailed 
catch tables presented in this report. In addition, there are included 
supplementary tables for most of the sections, which give data on the 
