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© Robert Pittman | NOAA
The killer whale population in the Puget Sound in Washington state has been dropping quickly, worrying environmentalists. Only about 78 orcas now live in the sound, a level not seen since 1985, and the social pods they live in are splintering.
The killer whale population in the Puget Sound, a sound in Washington state whose area includes Seattle, is rapidly declining. No whales have been born since 2012, two years ago. Two whales died this year.

The Center for Whale Research said that the whale population has grown as low as 78, the lowest it's been in the past 20 years, since 1985. The whales are also acting erratically, and seem to be splitting up from their social groups, called pods. There are three pods that make up the population in the Sound, pods J, K, and L.

Ken Balcomb, a researcher who works in Washington, has been studying the orca population in the Puget Sound since 1976. Every year, he does a census of the whales, which he gives to the U.S. government. These "Southern Residents," as they are called by environmental scientists, are under federal protection by the Endangered Species Act.

The three pods that live in the sound usually congregate during the summer, but in the last few years the pods have seemed to be splintering apart. These small groups have been tending to stay away from each other. Balcomb said that two or three members from a pod have been swimming around in their own group, with some members from different pods joining each other. The whales seem to be making a new social order.

"If we were trying to name the pods now, we couldn't do it," Balcomb said. "They aren't associating in those patterns anymore."

The orcas form matrilineal groups, where children often stay with their mothers until they die. The whales are still swimming in these groups, with mother, grandmother and children all together, but the "matriline" groups are smaller now than they were in years past.

One major reason why the whale population in the sound is decreasing is there's not enough food to support the population. The whales subsist mostly on chinook salmon, but the chinook population is itself declining.

"The salmon issue is huge, and it is ongoing," Balcomb said.

Federal officials have been striving to maintain the chinook population, but it continues to decline. Things like hydropower, which disrupts the water, make it hard for the salmon population to sustain itself.

Two orcas from the L pod have been presumed to be dead after going missing. The orcas were young, one 37 years old and one 13 years old. The average orca lifespan is 50 to 100 years.

Balcomb said that the whale population could make a comeback if females resume having children about every five years, and continue that trend, "but the chances of that happening are pretty slim." The gestation period for an orca is about 17 months, and the young whales nurse for a year, sometimes two. A female whale can bear a calf every three to five years, researchers have found, and sometimes go as long as 10 years between calves.