Federal investigators are looking into the cause of death of a large right whale discovered near Boothbay Saturday.  A spokesperson for Marine Resources said a 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 in the North Atlantic.  Trucker Paul Smith had the job of hauling the whale from the Portland waterfront to a farm in Gorham. Smith said it is something he will never forget. "He says, 'It's like the whale that's in 'Moby Dick.'' He goes, 'That's the kind of whale it is,' and I said, 'That's big then,'" Smith said. The whale was the size of Smith's trailer. "So when I am hauling this whale I'm going, 'This thing is as heavy as a load of logs,'" Smith said. The whale was 43 feet long, weighing in the ballpark of 45 tons, officials said. The whale bent posts and left oil on the trailer. "We've pressure-washed the trailer two times and there's still (material left behind). That's going to be there for a while," Smith said.  The whale ended up at Benson Farm in Gorham where researchers examined it. The necropsy is nearly complete. Scientists with NOAA said tissue samples were taken to be studied. The whale's carcass will be left at the farm. "What was left over was the basic skeleton of the whale. That's in this first pile composting," Eddie Benson said. The official cause of death has not been determined but experts are citing "severe entanglement as a contributing factor," Goebel said.  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.  More information about the whale's death is expected to be released Tuesday.