Orca hormones linking pregnancies to prey will go into medical files

Hormones found in the feces of killer whales are providing unique insights about the health of Southern Resident orcas — including pregnancy status and stress levels. Fortunately, such information can be gathered with little disturbance to the animals.

Tucker, a Labrador retriever mix, has a keen ability to track down killer whale feces, which contains trace levels of hormones and toxic chemicals. // Photo: Kelley Balcomb-Bartok

The latest information about hormones will soon be incorporated into a new health-status database with individual medical reports being compiled for each whale in the Southern Resident population.

A recently published study confirms hormonally what researchers have observed for years, that when the whales’ primary food supply — chinook salmon — is plentiful, the number of newborn calves goes up. Conversely, when the food supply is low, population growth seems to stall out or go down.

Now, thanks to the new hormonal report, we are learning that nearly two-thirds of the pregnancies among Southern Resident killer whales end in miscarriages. And, of those miscarriages, about one-third take place during the last stage of pregnancy — something highly unusual for mammals.

We are also learning that nutritional stress — caused by low food supplies — can be linked to the success or failure of the pregnancies, thanks to ongoing studies by a research team led by Sam Wasser, a University of Washington professor and director of the Center for Conservation Biology. Information about nutritional stress comes from fecal samples collected with the help of Tucker, a poop-sniffing dog who follows the whales in a boat.

I reported on Sam’s findings nearly a year ago for the Encyclopedia of Puget Sound after he presented the results during the Salish Sea Ecosystem Conference in Vancouver, B.C. His findings were published 10 days ago in the online journal PLOS One.

The hormonal information has been collected along with DNA samples from a growing number of Southern Residents, providing key information about the health of individuals as well as the overall status of the population.

Sam’s data will be included in a database being compiled to provide as much medical information as possible about each of the killer whales. I first reported details about the database in Water Ways on March 29, 2016. As mentioned in the blog, the medical files could be valuable in helping the whales throughout their range or even intervening when an animal goes into a health emergency.

General observations could be put into the database along with:

  • Fecal samples, including levels of various hormones;
  • Breath samples, including the types of bacteria harbored by individual killer whales;
  • Observations of skin conditions;
  • Photos taken from boats and from the air to show body conditions, including evidence of malnutrition or possible pregnancy; and
  • Blubber samples for some whales, including DNA fingerprints and other health conditions.

Joe Gaydos of SeaDoc Society, who is helping coordinate the database, told me that the project is finally getting off the ground this summer with formulation of the database structure. Commitments are coming together from those who can contribute information, including observations as soon as they are collected by researchers — including those with the Center for Whale Research and NOAA’s Northwest Fisheries Science Center.

A memorandum of understanding has been drafted to allow various researchers who submit information to have access to the data but limit access only to specified groups, Joe said. A governing body will oversee creation and use of the database. So far, information is being submitted on a “good-faith handshake.”

At least two research reports are being planned to prove the value of the database and build support for funding. One could be a paper that puts together information about skin diseases observed in the Southern Residents, mainly compiled by the Center for Whale Research.

Another report could look at the relationship between contaminants and pregnancy, including information collected by Sam Wasser.

“We are where we wanted to be a year ago, actively updating data,” Joe admitted to me, adding that things are now coming together more rapidly.

More information:

The latest report on orca pregnancy and nutritional stress is described in UW Today.

News stories were published by the Seattle Times as well as The Associated Press.

Previous work by Sam Wasser’s associate Katherine Ayres focuses on stresses caused by lack of food and boating activities. See PLOS One, June 6, 2012, or review the summary in UW Today.

Leave a Reply

Your email address will not be published. Required fields are marked *

Before you post, please complete the prompt below.

Please enter the word MILK here: