The evolutionary benefit of menopause in humans is to increase the survival of grandchildren. Testing this “grandmother effect” in a marine mammal is challenging, but further studies indicate they do mirror their human counterparts, as discussed in a recently published paper—Postreproductive killer whale grandmothers improve the survival of their grand offspring. Other than humans and killer whales, only three other species of toothed whales live beyond their reproductive years, making this a fairly unique trait in the animal kingdom.

Southern Resident Killer Whales live in a matrilineal society, where their ancestral family tree is traced back through the female lineage. Both sexes of offspring stay with their mother (known as their matriline) for their entire lives. As she moves into menopause (at a similar age to humans), she can become the matriarch— the leader of her extended family of children and grandchildren—and so can pass on both the cultural and ecological knowledge learned in her lifetime.

Countless decades of shared knowledge regarding the best feeding grounds for salmon in an ever-changing ecosystem is an invaluable resource for these whales. All of this highly detailed and varied information—encompassing geography, oceanography, and biology necessary to understand the unique life history of six species of Pacific salmon—is learned and passed through the family to support future generations.

These females living in their post-reproductive (senior) years without the stressors of giving birth and raising their own calves can also take some of the strain from their daughters in other ways—offering babysitting services, sharing food, and teaching skills in identifying and capturing prey.

The most well-known matriarch of the Southern Resident Killer Whales is identified as J2, and affectionately known as Granny. At the start of the study in the 1970s, she was already beyond her calf-rearing years and estimated to be over 50. At the time of her death, it’s possible she was over 100 years old and was very clearly matriarch not just of her own extended family, J pod, but of the entire Southern Resident Clan J, K, and L pod.

J2 'Granny' / Wild Orca

During Granny’s lifetime, populations of salmon—especially Chinook, the preferred species of these whales—have plummeted due to overfishing, habitat destruction (logging, dam building, pollution), and of course climate change. In years of low salmon numbers, the impact on these whales is reflected in an increased number of deaths and low, or no births. The reliance on grandmother whales would increase significantly in times of such scarcity. Survival itself is at stake.

Granny was a possible grandmother to Samish (J14), also a grandmother. Samish likely had followed Granny her entire life and so would have become an important source of knowledge after Granny’s death. But without any sign of apparent ill-health, Samish, age 42, was not seen again after the summer of 2016. In the last 10 years, 13 females over the age of 40 have been lost from the Southern Resident population and six of those, like Samish, were also under the age of 50. For a long-lived species, these losses are of enormous concern.

Miscarriage, stillborn calves, or calves not surviving after the first few hours or days are increasingly common. Collected and analyzed fecal (poop) samples show that these whales are undernourished and stressed with high levels of toxins carried through the food chain and stored in their blubber. In addition, the strong social bonds between these animals add to their emotional distress, as clearly exemplified by Tahlequah (J35) when she carried her deceased newborn for 17 days in 2018.

Taylor Shedd, Soundwatch/NMFS 21114

At the start of 2020, the Southern Resident population stands at only 73 whales, and only four matrilines have the benefit of a grandmother. These grandmothers (Sequim, Marina, Nugget, and Shachi) range in age from 40 to 47, and are perhaps without the deeper experience of the older grandmothers of previous generations.

With only 21 prime breeding age females, the future looks bleak for future whale grandmothers without recovery of the salmon on which they are so dependent. These animals deserve a chance to reach old age and to share their wisdom with their young grand calves. This unsustainable loss is a loud and relentless signal from our seas that time is quickly running out and we must act soon to bring Chinook salmon back to the Salish Sea, and restore this special ecosystem before it’s too late for this unique and special whale society.

Take Action for

Habitat Protection

We need your help.