Live Sei and Minke whales were observed underwater off Japan by a new method using commercial catcher boats. A non-explosive harpoon was fired into the tail region of a whale and a diver approached the “tethered” live whale.
After initial flurries, Sei and Minke whales swam steadily ahead of the catcher and could easily be approached by a diver. They took absolutely no notice of the diver. Live Sei and Minke whales kept their mouths tight shut all the time, but immediately after death the lower jaw always fell open. Little blood was emitted from the harpoon wound. The flippers were raised laterally when a whale surfaced and held against the sides of the body when it dived.
The body shape of both rorqual species was streamlined and the throat region was quite flat, not in any way dilated. The classical baggy-throated illustrations of rorqual whales do not show the true shape of live animals.
Sperm whales harpooned by the same method swam about wildly, shed much blood and could not be observed underwater.