Activists in the Philippines have rescued what they believe might be the smallest offspring of the world's biggest fish — a whale shark the size of a forearm, a conservation group said Tuesday.The World Wide Fund for Nature said maritime officials and activists in Pilar town in the eastern Philippines rescued the 15-inch-long whale shark last week and released it in deep waters. Its tail was tied to a small rope on a beach.The group called it "arguably the smallest living whale shark in recorded history."WWF said the discovery is the first ever indication that this coastline may be their birthing ground. The group has encountered very few baby whale sharks and can only compare the size of its new discovery to embryos found in a dead female in 1996 — which measured 14.6 to 18.9 inches, according to Elson Aca, project manager for the WWF whale shark tracking project.The gentle creatures, which can grow to be as big as a bus, make regular stops along the Philippines' eastern shores from December to May, attracting thousands of tourists. But little is known about where they breed as they cruise the world seas.