The plane circled slowly, searching. The US Navy pilot and crew had been trained to locate and report the position of the prey under the waves. Once sighted, a message would be sent to the US Navy Air Station ashore which then relayed the sighting to a subchaser or US Coast Guard cutter in the area. The warship would signal 10 to 15 pursuit vessels, inform them of the prey's reported location and the hunt would begin (Scofield, 1920). All the men in the air and on the sea were searching for the bright crescent of light that would be visible during the dark of the moon (Scofield, 1924). The inner edge of the crescent would be green and the outer edge red (Daniel Miller, private communication, 19 September 1989). Once a vessel sighted the crescent of light, the entire attack fleet would employ a number of capture techniques to ensnare the prey.

This was no hunt for an enemy submarine, but the latest twentieth century technology being used in 1919 to assist fishermen off the San Diego area in locating schools of Pacific sardine, Sardinops sagax. Sardines were just beginning to be used by the canning industry. Sardine canning started on the US west coast in 1889 at the Golden Gate Packing Company of San Francisco (California). When the San Francisco plant closed in 1893 the equipment was sold to the Southern California Fish Company in San Diego (Thompson, 1926).