Yuko Tajima oversaw production of a life-size specimen of a sperm whale at the "Mammals 2--Struggle for Life" exhibition being held at the National Museum of Nature and Science in Tokyo through June 16. (Saki Rin)

Yuko Tajima sees her job as interpreting the clues that dead whales leave behind, and whether human activity was to blame for their demise.

Each time a report arrives of a whale carcass washing ashore, the marine biologist rushes to the site to ascertain the cause of death.

Tajima works at the National Museum of Nature and Science in Tsukuba, Ibaraki Prefecture.

As whale carcasses tend to give off a terrible stench, local residents and fishermen generally press for the remains to be removed as quickly as possible.

But Tajima, 48, needs to carefully observe, measure and dissect each mammal. Did the whale die of disease? Had it become entangled in a fishing net or perhaps collide with a boat?

To buy time to solve these riddles, Tajima relies on her charm to win over annoyed fishermen and curious onlookers by sharing her expertise in an engaging manner.

“This is the heart, and what is left in the stomach tells us a lot about the species,” she explains on one occasion.

Tajima examines 50 or so carcasses a year. She has been doing this for about 20 years.

The National Museum of Nature and Science in Tokyo’s Ueno district tapped her expert knowledge to oversee work to create a life-size specimen of a sperm whale that is on display at an exhibition hosted by the facility titled “Mammals 2--Struggle for Life.”

Tajima, a native of Saitama Prefecture, has been fascinated with animals since she was a child. She studied pathology at Nippon Veterinary and Life Science University in Tokyo.

When Tajima was weighing which species to focus on for future research, a book recommended by her mother played a key role in shaping her career choice.

The book was about the killer whales, an apex predator that is known for being highly social, especially within family groups.

“I didn't realize then that orcas are so dedicated to raising their calves, given their reputation as gangsters of the ocean," Tajima said, referring to “sweet side” of the species.

A trip she made to Canada to see orcas in the wild determined her future path.

Tajima said human activity is taking a heavy toll on cetaceans in general.

For example, bits of plastic were discovered in the stomach of a dead blue whale calf that washed up on a beach in Kamakura, Kanagawa Prefecture, last summer. The calf was estimated to be only several months old.

The finding offered further proof that the world's oceans are contaminated with plastic waste.

“Marine mammals give us a message through their dead bodies,” Tajima said. “I am a translator of that message.”