By Katie Keil and Kaitlin Lebon

This story is part III of the Simply Science Series, where we’re delving into research conducted in our own backyard

They’re local celebrities, Puget Sound hallmarks, key ecosystem players, and, unfortunately, endangered. Although they should be rebounding from (now banned) live harvest captures in the 1970s, the Southern Resident killer whale (SRKW) population has remained relatively stable at low levels for years. Recovery looks grim: as much as 69% of detectable SRKW pregnancies end in abortion and explanations have eluded scientists until recently. Now, researchers from the University of Washington (UW) are getting closer to some answers thanks to a crew of unlikely heroes—poop-sniffing canines.

These dogs, who detect and lead researchers to orca poop, are invaluable because feces are a data gold mine: they provide information about diet, presence of parasites, hormone levels, and exposure to pollutants. The SRKW population faces a variety of challenges in the Salish Sea—declining prey, vessel disturbance, and pollution— but Dr. Samuel Wasser, a research professor at UW, is using feces data to help pinpoint the primary stressor.

His team evaluated several types of hormones, including one that measures immediate stress (such as a vessel disturbance) and another that measures nutritional stress (such as a lack of food). By analyzing these hormones’ levels in the orca feces, Wasser’s research suggested that low availability of SRKW’s primary food source, Chinook salmon, was the most significant stressor. Food stress is especially problematic because when orcas burn their fat to stave off starvation, they release toxicants previously stored in their fat layer into their bodies. These toxicants can suppress reproductive health among other adverse health effects, and even transfer to orca calves through both gestation and lactation.

These findings help managers prioritize SRKW conservation measures, and would not have been possible without the help of Wasser’s dog teams. Many of these dogs were considered unsuitable for family life because of their high energy and “ball fixation” — but it is this intensity that makes these dogs perfect for sniffing out scat. Conservation Canines, a non-profit program pioneered by Wasser, has saved many of these dogs from spending their lives in shelters or being euthanized, and instead gets them out where they love being most: the water.

Canines are especially well-suited for the job because their sense of smell can be 10,000 to 100,000 times more acute than that of a human. Proportionally, the part of the brain devoted to smell is 40 times greater than ours, allowing them to detect contaminants in concentrations as low as 2 parts per billion (ppb). The 21 dogs in the Conservation Canines program help scientists who rely on feces for their science significantly increase their sample size.

However, orcas aren’t the only things these canine wonders help save. Dogs have been used to detect the feces of endangered animals since 1997, and the UW program now contracts out its specially trained dogs around the world. Conservation Canines have been used to monitor elusive creatures like tigers, spotted owls, and Pacific pocket mice.

Overall, Wasser’s research findings illustrate that a healthy, reliable food source is crucial for SRKW recovery. However, Chinook salmon populations are at historic lows, so it’s clear conservation efforts for both salmon and orcas will be necessary to help SRKWs remain a cornerstone of the Pacific Northwest’s identity for generations to come. Thankfully, Wasser’s Conservation Canines are around to help scientists answer crucial questions regarding orca population trends, and thus make informed conservation and management decisions. With their support, SRKWs may be helped before it is too late.

Scientific paper source: Wasser, S. K., Lundin, J. I., Ayres, K., Seely, E., Giles, D., Balcomb, K., … & Booth, R. (2017). Population growth is limited by nutritional impacts on pregnancy success in endangered Southern Resident killer whales (Orcinus orca). PloS one, 12(6), e0179824.