Through the courtesy of Mr. Stewart Springer, I had the opportunity to make Cruise No. 23 of the United States Fish and Wildlife Service M/V Oregon to the Western Gulf of Mexico during May and part of June, 1954, and to record the observations on the spotted dolphin, Stenella plagiodon, noted below. Sight records are summarized in Table 1 and Figure 1. The numbers in parentheses refer to Figure 1. All of the observations of the spotted dolphin recorded in Table 1 were made in the immediate vicinity of the vessel, primarily around and in front of the bow, though on two occasions, positions (6) and (8), the individuals were seen to follow a large otter trawl to the surface as it was being hauled in. Both of these times the dolphins milled around the filled cod end of the net until it was actually brought on board. Only once, the afternoon record at position (2), did the animals stay with the vessel more than a few minutes, ten or less. They usually ran with the ship just at the bow, occasionally darting away and returning before disappearing very rapidly, as they had appeared. The ones at the bow usually held their speed with that of the vessel, which ranged from a near standstill to approximately ten knots. Their frequency of blowing also seemed to be correlated with the speed of the ship. When moving rapidly they blew every 5–10 seconds, and when nearly motionless (when the vessel was almost stopped) they blew only once every 60–120 seconds.
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David K. Caldwell (1955) studied this question.