Task: Question Answering
Input (English): Passage: A poacher hides from an unknown creature in his boat. While it breaks through the boat and attempts to catch the poacher, he commits suicide by shooting himself dead to prevent the beast from killing him.
Meanwhile while shooting a documentary about a long-lost indigenous tribe, the Shirishamas, on the Amazon River, director Terri Flores and members of her crew including cameraman Danny Rich, production manager Denise Kalberg, her boyfriend, sound engineer Gary Dixon, visionary Warren Westridge, anthropologist Professor Steven Cale, and boat skipper Mateo come across stranded Paraguayan snake hunter Paul Serone and help him, believing he knows how to find the tribe they are searching for.
Most of the crew are uncomfortable around Serone, and Cale clashes with him several times in regards to Shirishama lore. Later, while trying to free the boat's propeller from a rope, Cale is stung in the throat by a wasp inside his scuba regulator, which swells his throat shut and leaves him unconscious. Serone performs an emergency cricothyrotomy, seemingly saving Cale's life. With that, Serone takes command and captain of the boat and the crew. They are then forced to help him achieve his true task: hunting down and capturing a giant record-breaking female green anaconda he had been tracking the whole time.
Later, Mateo gets lost and is the first to be killed by the anaconda, which coils around him before it snaps his neck near the boat where the poacher had been killed. A photograph in an old newspaper reveals that Mateo, Serone, and the unnamed poacher were actually working together to catch animals, including snakes. The others try to find him while Gary sides with Serone, who promises if they help him find the anaconda, he will help them get out alive. 
Question: Who all believe that a stranded snake hunter can help locate the Shirishamas?
Output (English): Professor Steven Cale.