Onlookers watch a necropsy of the 45-foot female humpback whale named Snow Plow on Foss Beach in Rye, N.H., Wednesday, June 29, 2016. The necropsy is being performed Wednesday, days after she washed ashore in New Hampshire. Snow Plow had been studied since she was a calf in the southern Gulf of Maine. (Rich Beauchesne/Portsmouth Herald via AP) MANDATORY CREDIT
Onlookers watch a necropsy of the 45-foot female humpback whale named Snow Plow on Foss Beach in Rye, N.H., Wednesday, June 29, 2016. The necropsy is being performed Wednesday, days after she washed ashore in New Hampshire. Snow Plow had been studied since she was a calf in the southern Gulf of Maine. (Rich Beauchesne/Portsmouth Herald via AP) MANDATORY CREDIT Credit: ap — Rich Beauchesne

Rye, N.H. — When she first arrived on the scene, Ashley Stokes spotted the bloated carcass of a humpback whale lying on the beach, its tongue hanging out. She and her colleagues from the New Hampshire Marine Mammal Rescue team scanned the behemoth’s body but couldn’t find any signs of wounds or lesions.

Then, the real work began. Scientists wanted to understand why a seemingly healthy 45-foot whale that weighed as much as 40 tons — imagine a fully loaded 18-wheeler — beached itself. It turned up dead on June 26 after being noticed about 20 miles off Rye by fishermen. Its jet-black body was pushed by the tide and wind onto Ragged Neck Beach and then even farther onto Foss Beach in Rye.

Investigators had a few clues about the whale. Due to its unique tail markings, they identified the mammal as Snow Plow, an 18-year-old female that is part of hundreds that return to the Gulf of Maine each summer to feed. Scientists had been tracking the whales for years.

But her death remained a mystery. Scientists from the New England Aquarium were called in to perform a necropsy.

A team of about 30 — wearing yellow and orange waders, welder-like goggles, gloves and surgical masks — set to work on the whale Wednesday, using machete-like knives and meat hooks to cut huge chunks of blubber that were half a foot thick from the carcass. As the square chunks were removed and laid on the beach, teams of scientists examined and sampled the mammal’s organs for any clues.

As they worked, scientists raced to beat the tide, incoming storms and decomposing organs; that’s why the beach turned into a medical examiner’s table. But the biggest challenge they encountered was the size of the animal.

“This was an enormous whale,” said Connie Merigo, director of the marine animal and rescue and rehabilitation department at the New England Aquarium. “There is a lot of mass involved. … That is a lot of tissue to dissect when you are looking for mortality. For us, that is the goal. We want to know why she died. She should have had decades in front her and that wasn’t the case.”

Humpback whales live 60 years or more and usually die of natural causes.

Merigo said her team was looking for anything “out of the ordinary,” from evidence of parasites, to unusual lesions to blunt force trauma from collisions with ships.

But as the necropsy ended, clues to her death remained elusive. Tissue samples from the whale are being sent to several labs for additional study.

The chunks of blubber will be turned into compost and fertilizer. The bones will be buried by the Massachusetts Fisheries and Wildlife to allow microbes and insects to clean them. Then, the skeleton will then be exhumed and eventually displayed at a museum.

“It really makes you appreciate their sheer size,” Stokes said. “It’s one thing to see them from a whale-watch boat. They look big. When you are standing next to one … just to see the sheer size of these great whales is amazing.”