. Commercial fisheries review. Fisheries; Fish trade. 16 COMMERCIAL FISHERIES REVIEW Vol. 12, No. 11 supplies a constant flow of sea water to a number of spray outlets which are situ- ated at 3-to 4-foot intervals along the walk frcm vAiich the fishing is done. A 125- gross-ton vessel will have one or two centrifugal pumps with l+- to 5-inch intakes. These deliver water into one or two header pipes, depending on- whether fishing is done fran one or both sides of the ship. A distributing pipe is laid along the fishing walk (Figure 15). Near the header this pipe is 4 or 5 inches in diameter, but
. Commercial fisheries review. Fisheries; Fish trade. 16 COMMERCIAL FISHERIES REVIEW Vol. 12, No. 11 supplies a constant flow of sea water to a number of spray outlets which are situ- ated at 3-to 4-foot intervals along the walk frcm vAiich the fishing is done. A 125- gross-ton vessel will have one or two centrifugal pumps with l+- to 5-inch intakes. These deliver water into one or two header pipes, depending on- whether fishing is done fran one or both sides of the ship. A distributing pipe is laid along the fishing walk (Figure 15). Near the header this pipe is 4 or 5 inches in diameter, but may taper to 1 or 2 inches in diameter at the end. From the main pipe, short lengths of 3/4-inch-diaraeter pipe point outboard. A few feet of rubber hose, bearing a piece of brass tubing, are at- tached to the end of this pipe. The brass tubing is flattened to squirt water as a horizontal, fan-like spray. The water pressure is low and such that a gentle spray falls between 6 and 18 feet from the hull of the vessel, forming a ruffled band which will be frcsn 4 to 8 feet in width. Because the major portion of the catch in the past has been consumed fresh (unfrozen) or dried, mechanical refrig- eration equipment in the skipjack vessels is lacking or of relatively small capacity. Only recently has there been serious in- vestigation of brine-freezing of tuna aboard the vessel for canning on shore. In most cases ice is carried to prevent spoilage, and voyages are short in duration. It must be noted that this applies only to the skipjack fishery. The tuna long-line vessels (which catch other tunas) may spend a month or more fishing. However,since the skipjack are taken in warm waters (66° ° F.), many of the larger vessels have small ammonia systems to cool the holds and thereby prevent the ice from melt- ing as rapidly as it ordinarily would. The use of radios among the fishing fleet is of a highly organized nature. In almost every tuna fishing center of any importance, there
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