382 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
of the fish before freezing and the care exercised in the process of freezing, and, sec- 
ondarily,. on the length of time they remain in cold storage. The loss in quality during 
storage is due principally to evaporation, which begins as soon as the fish are placed 
in storage and increases as the ice coating is sapped from the surface. 
Evaporation proceeds at very low temperatures, though not so rapidly as at 
higher ones; even at a temperature of 0° F. the evaporation during two or three mouths 
is considerable. The heavier the ice coating the less the evaporation, but it is almost 
impracticable to entirely prevent it, aud under ordinary conditions it amounts to 
about 5 per cent in weight in six months, but the loss in quality is greater than the 
loss in weight. 
The method generally adopted of restricting evaporation other than coating with 
ice is to wrap the fish in waxed or parchment paper and place them in shipping 
boxes whose length aud width are slightly larger than the blocks aud deep enough 
to contain 4 or 5 blocks, or 120 to 150 pounds of fish, the inside of the box being lined 
with wrapping paper. 
A method of largely reducing evaporation was invented and patented in 1880 by 
Mr. W. B. Davis, of Detroit, Mich., but it is scarcely sufficiently practical for general 
use, especially with cheap grades of fish. It consists in freezing the fish as above 
described, except that they are packed in fine pulverized ice in the pans before being 
frozen, and when taken out of the i)ans the fish are found solidly imbedded and 
incased in the block of pulverized ice. 
Along the Great Lakes the most popular fish for cold storage are whitefish, lake 
trout, lake herring, blue pike, saugers, sturgeon, perch, wall-eyed pike, grass pike, black 
bass, catfish, and eels. In addition to these species the Great Lakes freezers receive 
considerable blueflsh and squeteague from the Atlantic. On the Atlantic coast 
bluefish, halibut, squeteague, sturgeon, mackerel, fiatfish, cod, haddock, Spanish 
mackerel, striped bass, black bass, perch, eels, carp, and pomiiano, are frozen. Salmon, 
sturgeon, and halibut are the principal species frozen on the Pacific coast. 
Some varieties of fish are so very delicate that it is not deemed profitable to freeze 
them, especially shad, bnt even these are frozen in small quantities. Oysters aud 
clams should never be frozen, the best temperature for cold storage being 35° or 40° F. 
When stored in good condition they will keep about six weeks. As an experiment 
they have been kept for ten weeks, but storage for that length of time is not advisable. 
Caviar also should never be frozen, but held at about 40°. Scallops and frog legs, 
however, are frozen hard in tin buckets and stored at a temperature of 16° to 18° F. 
Sturgeon aud other fish too large for the pans are frequently hung up in the storage 
rooms by large meat hooks, and when frozen are dipped in cold water and stored in 
piles. But when intended for shipment sturgeon are usually cut into pieces of suit- 
able size for packing in the shipping boxes. 
In some of tlie largest freezing houses on the Atlantic seaboard, which freeze and 
store fish as well as other food products, the fish to be frozen are simply hung ui) in 
the sharp freezer, the heads being forced on to the sharp ends of wire nails protruding 
from cross lathes arranged in series. After the fish are frozen they are removed and 
piled in storage rooms, where the temperature is about 15° or 18° F. (See plate xii.) 
Where the handling of fish is of minor importance compared with other food prod- 
ucts, the fish are placed on slat- work shelves in either a special freezing room or in a 
storage room where the temperature is kept below 20° (see plate xli, lower half), or 
