The Clubbed Thumb theater company follows up last year’s excellent Grief Hotel with another gem that originated in its  Summerworks program, Abe Koogler’s Deep Blue Sound, in which a group of islanders in the Pacific Northwest mourn the disappearance of a nearby pod of orca whales. The production, in residency at the Public Theater, is astonishing: Koogler’s play is both strange and naturalistic, as funny as it is deeply moving, even shattering; Arin Arbus’s note-perfect direction is mesmerizing, smartly enhancing the emotional climaxes but never overdoing them; and the ensemble of nine is simply extraordinary.