Federal investigators are looking into the cause of death of a large right whale discovered near Boothbay Saturday.A spokesperson for Marine Resources said marine patrol assisted in towing the body to shore. It was found tangled in ropes and was later towed into Portland Harbor.NOAA Fisheries Spokesperson, Jennifer Goebel, said the whale was initially spotted Friday by a Portland whale watching boat."Northern right whales are the rarest, and most endangered type of great whales, and are both a federally-protected and endangered species," Goebel said.She added there are only 500 remaining individuals within the entirety of the North Atlantic Population.On Sunday, a necropsy was performed at a farm in Gorham.The whale was 43 feet long, weighing in the ballpark of 45 tons.The official cause of death has not been determined but experts are citing "severe entanglement as a contributing factor," said Goebel.Marine Resources say nearly a dozen agencies are investigating both at the local and federal levels including the NOAA fisheries, The Riverhead Foundation and Marine Mammals of Maine.