While the credits state that the film is based on Herman Melville's novel, the first page of the novel shown onscreen right after the credits is entirely written by one of the screenwriters; it has absolutely nothing to do with Melville's original, and even leaves out Melville's classic opening sentence, "Call me Ishmael".
The opening sequence when we see the Call-me-Ishmael-less paragraph is lifted from the earlier version, THE SEA BEAST (1926), which also took liberties with Melville's novel. It seems that MOBY DICK (1930) was a remake of this film more than an adaptation of the novel.