Back in the lab, biologists get a snapshot of the orcas' health using hormonal information extracted from the samples. Unfortunately, the hormones and other data paint a grim picture. Southern resident orcas, which spend May to October in the Salish Sea, are "doing really bad right now," Wasser says.
There are only about 79 resident killer whales left, legally protected as an endangered species in the U.S. In the 1960s, there were nearly 150 resident orcas living in the waterway between Canada and Washington. But, based on a critical miscalculation by the captive orca industry -- which had assumed the whales numbered in the thousands, not hundreds -- 48 resident whales were harvested by the mid-1970s.
Forty years later, the orca population has not recovered. The whales' health is closely tied to the health of Chinook salmon in the Pacific -- resident orcas are picky eaters, subsisting on these salmon for nearly 70 percent of their diet. When the Chinook salmon population dips, orcas go hungry. Based on hormones in the orca scat (found by Tucker), Wasser and his colleagues can tell how well the whales are eating.
When the whales return to the Salish Sea in May, hormones indicate the marine mammals arrive well-fed, Wasser and his colleagues report in a 2012 PLOS One study. It was a surprising finding -- it meant the whales also dine at a source of salmon outside the Salish Sea. The orcas, it turns out, were hunting at the mouth of the Columbia River before their northward swim. It's a critical habitat that, prior to this discovery, the National Oceanic and Atmospheric Administration hadn't been monitoring for orcas.
Both Seely and Wasser point out that Conservation Canines doesn't only help killer whales, Mexican gray wolves and other endangered species -- for the detection dogs, the program is home. Tucker, like his canine teammates, were all adopted, either from shelters or families who couldn't keep their pets. "They're the crazy, crazy ones that don't usually find a home," Seely says. "We get to give them a second chance -- and go all over the world to help endangered species. And the dogs are happy to do it, just to play with a ball."
And among his human colleagues, it seems, the feeling is mutual. "Tucker's just about the sweetest dog there is," Wasser says. "There're few greater pleasures I get than watching him work."