Early in Star Trek IV: The Voyage Home (Leonard Nimoy, 1986), in which a space probe threatens to annihilate the earth unless it gets a response to its cryptic, ocean-directed signal, Kirk instructs Uhura to manipulate a recording of the signal. Modifying it to account for “density, temperature, and salinity factors,” Uhura reveals what the signal, in Kirk’s words, “would sound like underwater.” For many viewers in 1986, the resultant “mroo”s would have been instantly recognizable: humpback whale song—sounds that had proliferated in pop culture for most of two decades. The sonic history of whale song begins with the 1970 LP Songs of the Humpback Whale, a collection of hydrophone recordings released by marine biologist Roger Payne, who furnished Nimoy with the recordings used in the film. The same year heard Alan Hovhaness’s And God Created Great Whales and Judy Collins’s “Farewell to Tarwathie,” both of which featured humpback songs, as well as Pete Seeger’s anti-whaling plaint “The Song of the World’s Last Whale.” In 1977 NASA launched whale songs into deep space on its Voyager Golden Record; the following year, Kate Bush hit #1 in Japan with “Moving,” which opened with a twenty-second whale aria. The high-water mark for whale song was arguably the January 1979 issue of National Geographic, which delivered to millions of readers a flexi disc of humpback phonations set to an explanatory narration by Payne. Bookending this history was Paul Winter’s 1987 Grammy-nominated New Age record Whales Alive, coproduced by Payne and featuring prose and poetry readings by Nimoy, whose presence on the record reinforced Star Trek IV’s place in this lineage. In using whale songs to motivate its save-the-whales time-travel narrative, Star Trek IV deploys them in a manner consistent with the discourse that surrounded them from start. Throughout the seventies, whale songs were pivotal in spreading the idea that cetaceans were supremely benevolent and intelligent beings threatened by “human arrogance” (to quote Spock) before the natural world—arrogance that would drive not only whales but eventually humankind itself to extinction. In having the crew return to 1986 San Francisco to transport a pair of humpbacks to the twenty-third century, where they’re extinct, to sing to the probe and save the planet, Star Trek IV literalizes Seeger’s earlier call to conscience: “If we can save our singers in the sea, perhaps there’s a chance to save you and me.”