What types of research were used in the documentary The Cove?

In the documentary "The Cove," a combination of investigative journalism, observational research, and scientific studies is employed to expose the dolphin hunting practices in Taiji, Japan. The filmmakers use hidden cameras and underwater microphones to capture evidence of the hunts, while also incorporating interviews with marine biologists and activists to provide context and scientific insights. Additionally, the film highlights historical and cultural aspects of dolphin hunting, blending emotional storytelling with factual data to engage viewers on multiple levels.