Whale shark populations have plummeted since the 1980s due to targeted fishing, boat strikes and collateral damage from fishing, oil and gas exploration, and shipping, and an international team of scientists is studying the giant creatures to better understand their reproductive patterns. Marine biologist Rui Matsumoto recently donned diving gear and performed ultrasound examinations and blood draws on 21 whale sharks in the Galapagos Islands, and he and his team also outfitted them with tracking tags.