The world’s oldest known killer whale has gone missing and is presumed dead after living an estimated 105 years, researchers announced Monday evening.

Nicknamed “Granny,” the iconic century-old Orca played a vital role in not only leading the younger members of her family to forage for food, but also in observational studies over the past few decades that allowed researchers to seek protections for the whales and learn from their unique family structures.

"We knew this day would come, and each year that she returned with the rest of J pod brought us closer to this inevitable moment," the Center for Whale Research (CWR) wrote on Facebook Monday. "With heavy hearts we have to say goodbye to yet another southern resident, perhaps the most loved and known to all and the oldest orca to date: J2 also known as Granny."

Granny, whose official name was J2, lived in the Salish Sea near Vancouver and Seattle and became part of a four-decade long study that began in 1976 after many whales were taken to marine parks. Ken Balcomb of the CWR first encountered Granny in captivity, and by cataloguing and observing her and other whales both there and in the wild, he noted the unsustainable nature of whale hunting, eventually winning endangered species classification for the animals that has served to protect them in the wild.

Helping to guide her pod for more than 40 years, Granny is one of the only whales in the region to be born before the study began.

"And, she kept on going, like the energizer bunny," Dr. Balcomb said in a statement announcing her presumed death. "I last saw her on October 12, 2016 as she swam north in Haro Strait far ahead of the others. Perhaps other dedicated whale-watchers have seen her since then, but by year’s end she is officially missing from the [South Resident killer whale] population, and with regret we now consider her deceased."

While researchers who spent decades identifying Granny’s distinct dorsal fin shape mourn her loss, they have culled years of valuable data and information after observing her, including information on the unusual reproductive cycles of orcas.

Scientists have found that only three mammals experience menopause: orcas, short-finned pilot whales, and humans, with other animals experiencing declining fertility over time or dying before their childbearing years come to an end. By studying aging female orcas like Granny, researchers could see the vital roles they played in their families, and hope to continue to gain insight as to why some species have evolved remarkably similarly to humans in this aspect.

Today, there are 78 whales living in the area. But a continuously dwindling local salmon population has prompted many researchers to wonder what will happen to orcas in the region if their food source cannot be salvaged.

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Without Granny, researchers have several questions about the whales' uncertain future.

"Who will lead the pod into the future?" Balcomb asks. "Is there a future without food? What will the human leaders do?"