THE IMPORTANCE OF KILLER WHALE MATRIARCHS

Onyx and Spieden lr

This fall, whalewatchers off southern Vancouver Island are mourning the loss of one of the most venerable members of the southern resident killer whale community.

Eighty-year-old Spieden (J8), known for her distinctive wheezy breaths, disappeared from J-pod sometime in late September/early October and is presumed dead.

Spieden’s closest companions were 102-year-old Granny (J2), the grand matriarch of J-pod, and Onyx (L87), a 21-year-old male from L-pod.

Spieden’s disappearance is yet another blow to the endangered southern residents, who have now lost five key members in the last 12 months or so, including two adult males in their prime. The population—the entire gene pool—now stands at a precarious 81.

The loss of any whale from this population is a tragedy, but Spieden had a special role within J-pod. She was one of the pod’s matriarchs, and as such, was an essential source of cultural knowledge and social wisdom for the pod’s younger members.

Resident killer whale pods are led by these older females, who undoubtedly teach the younger generations everything they need to know—such as where to find food and when, how to find their way around the coast, and how to be a good mother.

The average life expectancy of a female killer whale in the wild is about age 50. They usually stop having calves around age 40, but can live on for decades. In fact, they have the longest non-reproductive lifespan of all animals, except humans.

Why? Is there something else going on besides the above-mentioned “granny” effect?

A recent study suggests the answer lies in the mother-son relationship.

The statistical study revealed that if you’re a male resident killer whale older than 30 and your post-reproductive mother dies, you are a whopping 13.9 times more likely to die in the year following her death. For daughters, the risk increases 5.4 times.

When mom dies, these adult males seem to struggle, says Dr. Ken Balcomb, director of the Center for Whale Research in Washington State. In 37 years of field research, he’s seen it happen enough times.

He’s convinced that mothers provide their adult sons with some form of critical social support. “Maybe they need a wise senior female who can be a ‘social introducer,’” he says.

While Spieden was the last of her matriline with no living offspring, in recent years she had “adopted” 21-year-old Onyx (L87). Onyx has an unusual story. He was 13 years old when his mother, L32, died in 2005. Shortly afterward, he “defected” from L-pod and hooked up with two older females in K-pod.

After they died, he shifted to J-pod and Spieden. Following her disappearance, he’s been travelling close to pod leader Granny (J2).

Onyx’s behaviour is very unusual for a resident killer whale, which normally stays in its pod for life. But his obvious need for the guidance of an elder female underscores again the importance of matriarchs to these whales. They are a major part of the glue that holds pods together.

The three southern resident pods have lost three matriarchs in the last year. And in the northern resident killer whale community off northern Vancouver Island—roughly 250 whales in 16 pods—eight matriarchs have died in the last two years.

It’s an alarming trend. And it means challenging times lie ahead for both populations.

Source: Vancouver Aquarium Cetacean Research Program at http://killerwhale.vanaqua.org/