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Study: Orcas Lose Two-Thirds of Their Pregnancies

Because the researchers can’t detect the pregnancies until a few months into the term, they suspect even more miscarriages have taken place.

June 29, 2017

Two-thirds of all detectable orca pregnancies have ended in miscarriages over the past seven years, a new study shows.

To figure out if orcas were pregnant, the researchers trained dogs to find orca scat and then tested the scat’s hormone levels. What they found was sobering.

“Of those that we confirmed were pregnant, 31 percent of the pregnancies are successful. So 69 percent were lost,” said Sam Wasser, a University of Washington professor and study author.

Tucker, a dog from the University of Washington Conservation Canines program, on a research boat following southern resident killer whales.  Center for Whale Research

Wasser said because the researchers can’t detect the pregnancies until a few months into the term, they suspect even more miscarriages have taken place.

The researchers point to a lack of food as a possible reason for the deaths.

In years with more salmon, orcas had more live births. And in years when salmon were scarce, orcas had more miscarriages.

“It’s the fish!” Wasser said. “If we don’t increase the carrying capacity of this system, these whales are doomed.”

Because 2017 has had low salmon runs, Wasser said orcas are likely to have a lot of miscarriages again this year.


Featured Image Caption:

L122, one of the newest members of the Southern Resident Community of orcas, spotted Sept. 7, 2016, near Sooke, British Columbia.

Dave Ellifrit/Center for Whale Research



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L122, one of the newest members of the Southern Resident Community of orcas, spotted Sept. 7, 2016, near Sooke, British Columbia.

Dave Ellifrit/Center for Whale Research