Charter fishing captain Jason Miller told Fox 4 that he and a friend were in Estero Bay Tuesday when they came upon a sad sight: a dolphin floating belly-up by the mangroves. "There were no signs of any foul play, any prop scars or anything like that," Miller said. Rick Bartleson, research scientist with the Sanibel-Captiva Conservation Foundation, believes the dolphin may have gotten sick from Karenia Brevis - better known as red tide. "We've been seeing lots of sick animals, and dying animals and fish around Sanibel," Bertleson said. "We've also been seeing high numbers of Karenia Brevis in our samples." He said high concentrations of red tide were detected in Estero Bay last week. "The dolphin can get sick from eating fish that have accumulated toxins," Bartleson said. Miller took photos of other dead fish in Estero Bay, including a freshwater alligator gar, which normally wouldn't be found in those waters. He thinks the Lake Okeechobee water releases are to blame for pushing the gar out to Estero Bay. "To see one that far north in water that should be a high salinity level just tells you the devastation that's happening now," Miller said. He said he expects muddy water runoff in the summer rainy season when business is slower. But as someone who depends on the waterways to make his living, having the water releases from Lake O at this time of year is putting his business in dire straits. "I've had numerous calls from regular clients that come down in April and May for tarpon fishing, and they're looking to go elsewhere," Miller said. "There's no short-term solution here, but something has to be done." Officials at the Estero Bay State Preserve told Fox 4 that they had not seen any dead fish or dead dolphin in those waters.