Japan's oldest harbor seal has died in Hokkaido at the estimated age of 46, or over 100 years old in human terms, the operator of Otaru Aquarium said Monday.

It said the female seal, named Tora, was found dead Wednesday in a pool at the aquarium, which is in the city of Otaru. Harbor seals usually live for about 25 to 30 years.

"She had been at the aquarium longer than any of our staff and taught us about seals since the time when we did not know much about the animal," said Director Nobuya Ise.

Tora, the oldest harbor seal registered with the Japanese Association of Zoos and Aquariums, was taken into shelter in 1970 and judged to be under a year old at the time.

While Tora had recently suffered from poor eyesight, she was eating octopus voraciously in September. It was only from late April that she lost her appetite and started sleeping much of the day, it said.

Tora was once washed away from a seaside pool in the 1970s by high waves but returned on her own, causing her to be named after Torajiro Kuruma from in the popular film series "Otoko wa Tsuraiyo (It's Tough Being a Man)," who causes a stir upon returning to his hometown.