Social Networks a Key to Orca Survival

Editor’s Note: This article was originally published in the Encyclopedia of Puget Sound.

Understanding the social networks and family bonds of Puget Sound’s southern resident orcas may be critical to keeping the endangered whales from extinction. A healthy population is about more than numbers, scientists say. It’s about connections.

Part 2

Females in the Lead
The notion of orca families isn’t entirely a recent one. In the cosmology of the Lummi Indian Nation, whose ancestral territories include the San Juan Islands, orcas are qwe ‘lhol mechen, or “our relations under the waves.”

A “spiritual feeding” ceremony in which the Lummi honor the qwe ‘lhol mechen involves placing salmon on cedar boughs in deep water to share with their relatives. When Lummi leaders performed this ceremony in January, “We had one live chinook to feed Princess Angeline, and a dead one to offer the qwe ‘lhol mechen ancestors,” Raynell Morris, senior policy advisor in the Lummi Sovereignty and Treaty Protection Office, wrote in a Seattle Times op-ed.

Princess Angeline (the name honors the eldest daughter of Chief Seattle) is also known as J17, a 42-year-old orca who was in poor condition, with the “peanut head” indentation behind her skull that is characteristic of emaciation, last fall.

“One potential explanation for what’s going on with her is her family group has been hit by a lot of tragedy,” says Monika Wieland Shields, president of the Orca Behavior Institute (see Part 1). J17 is the mother of J35, the whale Tahlequah who gained national attention last summer when she carried her dead newborn calf for 17 days and 1,000 miles — an ordeal that would have prevented her from foraging.

J17’s family group also includes a son and a grandson, ages 10 and nine; an orphaned 10-year-old granddaughter; a four-year-old daughter; and, of course, L87. “I can just imagine that J17 has been trying to feed these other whales, maybe at the expense even of herself — trying to keep her family members well nourished,” Shields says.

Female orcas over age 42 — J17’s age — are considered “post-reproductive.” But these older females remain crucial to the survival of their families, not just as providers but as leaders. Older females are often in the lead when groups of southern residents are traveling through foraging grounds. Sons are more likely to follow their mothers than are daughters. And, again, these older females are out in front more often when salmon are scarce.

Those findings suggest that older females are keepers of knowledge that benefits the population as a whole. “If they go to a particular place at a particular time expecting to have a salmon run available to them and it’s not there, then the older females know where to go next,” Giles says.

These whales may hold other types of knowledge important to the group as well: hunting methods, parenting techniques, expertise in mediating conflict. And all that may change conservation strategies and decisions about when to intervene medically to help a struggling whale, says Joe Gaydos, SeaDoc Society science director [Gaydos is also a topic editor for the Encyclopedia of Puget Sound].

Normally, saving endangered populations means investing the most money and effort in animals that can make lots more babies — not ones like J17 at the tail end of their reproductive years. “But then when you realize how many animals are dependent on her, you think: Oh, maybe we should rethink this,” Gaydos says. “This is actually a really important animal.”

Twilight of the Matriarchs
The southern residents currently have nine post-reproductive females across all three pods, but only one of them is over age 50. In the last decade, four of the population’s oldest females have died — whales in their 80s or 90s like L87’s foster mothers K7, J8, and J2.

That’s concerning because the whales with the longest memories likely hold the largest stores of ecological knowledge. “You want to preserve those information archives in the oldest animals. You also want to maintain enough diversity in information so that they can respond to environmental change,” says Kim Parsons, a marine biologist working as a contractor with the Northwest Fisheries Science Center. “The survival of the youngest often does depend on the survival of the oldest.”

Some scientists suspect that losses of older females (nine younger matriarchs have also died in the last decade) could be contributing to the fracturing of the southern residents’ pod structure. “Maybe it’s not just searching for food, but the older females are the glue that holds the group together,” Shields says.

The distribution of older females might also help explain why lately, matrilines from different pods even link up and travel together for a season or two. “Is there something about the group composition — ‘Hey, we don’t have an elder female in our group, so we want to travel with your group that does have one?’” Shields says.

The answers to those questions aren’t yet clear. Michael Weiss, a field biologist with the Center for Whale Research in Friday Harbor and a graduate student at the University of Exeter in the UK (see Part 1) and others are analyzing how southern resident social networks change after the deaths of post-reproductive females.

But scientists who pay close attention to the southern residents can see that something has changed. “When [J2] would want everybody to go a particular way, she would just slap her tail on the surface of the water. And you could see whales from literally miles away come directly to her side,” Giles recalls — not just whales from her own J pod but Ks and Ls as well.

“I don’t know that you would see that. I personally haven’t seen that with any individual southern resident killer whale since J2 died.”
____________________________________

Sarah DeWeerdt is a Seattle-based freelance science writer specializing in biology, medicine, and the environment. Her work has appeared in publications including Nature, Conservation, and Nautilus.

Bookmark the permalink.