Perhaps it is fitting that the last sighting of the elderly matriarch was just after Midwinter's Day. When it comes to orcas, the best data available to whale scientists on the Pacific north-western coast of North America is from their observations at sea. Lummi, thought to be 98 years old and the leader of a family group known as "K pod", was last spotted in Puget Sound near Seattle on 23 December last year.
Orcas, or killer whales, if you really want to annoy aficionados of the species, are thought to live in particularly stable social groups in this region. Up to five generations, taught and led by an ageing female, have been observed living and hunting together, ensuring social continuity.
The matrilineal pods have developed a sophisticated vocal system to communicate with and guide one another. This is partly thanks to the great ages that many of the females reach; males usually die decades earlier.
Now Lummi herself has disappeared and is presumed dead. As she and the 18 members of her extended family went out to sea last winter on their almost unknown winter travels, researchers could only wait until they returned to resume study. In June, K pod was finally sighted in offshore waters with a new calf, but without its oldest, most experienced member.
Erin Heydenreich, of the Centre for Whale Research in the San Juan islands of Washington State, said that Lummi's last photograph at the centre, showing the two distinctive notches in her dorsal fin, had been tinted grey in mourning. There is a slim chance she could still turn up - that perhaps she had, for some reason, decided to join other family groups in the region for a short period - but as the summer wears on it seems unlikely.
"It's not uncommon not to have seen her, but when K pod returned to inland waters on 3 June Lummi was not observed with the rest of them. That was the first time we thought she may have died over the winter," she said.
It is impossible to be certain of Lummi's age. The whale, which was named after a local native community, was over 60 when marine biologists started putting orca family trees together in the late 1970s. "That she was the oldest whale among our orca populations made her important," said Heydenreich.
K7, Lummi's scientific name, was among the first whales photographed when recording began 30 years ago. She was found to be well beyond reproductive years by then, Heydenreich also said, and helping her own offspring with their calves.
K pod, like the and J pods, which also live in the region, travels up and down the coastline between California and Vancouver Island. They are known collectively as the Southern Residents. K pod was severely damaged by whalers and by three decades of zoological capture to fill the pools of marine parks. Unlike orca groups in other parts of the world, it remains on the endangered species list. Its survival so far is thanks, at least in part, to Lummi.