FISHERY INDUSTRIES OF THE UNITED STATES, 1938 547 
monthly. Included with statistics of the holdings are statements of 
the quantity of the various species of fish frozen and also the holdings 
of certain cured fish. Bulletins showing these statistics are issued 
monthly as well as annually, and detailed statistics are published in 
the annual reports of this Division. Statistics of cold-storage holdings 
of fishery products have been published since 1917 and data on quan- 
tities of fish frozen, for the years from 1920 to 1925, inclusive, and 
from 1928 to 1937, inclusive. 
Sponge market, Tarpon Springs.—A large proportion of the total 
output of sponges in Florida is handled through the sponge exchange 
at Tarpon Springs. In view of this, the Bureau has obtained from a 
representative of the exchange annual statistics of the quantity and 
value of the sponges, by variety classifications, handled through it 
annually. Statistics of the quantity of sponges handled through the 
exchange are not published in bulletin form, but a summary of the 
year’s activities is published in the annual reports of this Division. 
Statistics of the transactions on the sponge exchange are available for 
1913, 1914, and for the years from 1917 to 1937, inclusive. 
Foreign fishery trade.—Statistics of the foreign fishery trade are 
obtained from compilations made by the Bureau of Foreign and 
Domestic Commerce, Department of Commerce. Statistics of all 
known fishery products imported or exported have been assembled 
in one table and published annually in the reports of the Division in 
recent years. For earlier years they are available in the reports of 
the Bureau of Foreign and Domestic Commerce, the Bureau of Sta- 
tistics, the Department of Commerce and Labor, or 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 
paiteeetigg 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 
