MONTEREY — In the days leading up to Halloween, a rare all-white dolphin named “Casper” has been frequenting the Monterey Bay. But sighting the perplexing creature isn’t a trick of the eyes, or just a spooky Halloween treat. The dolphin actually visits the region quite often, according to Nancy Black, a marine biologist with Monterey Bay Whale Watch.... ..Black and other scientists think the dolphin is around 9 years old — still a juvenile since Risso’s can live up to 35 years. Casper frequently travels with his mother and has been seen as far north as Davenport, with pods of...