There's a special group of orcas living in Washington's Puget Sound. The Southern Resident killer whales are a genetically distinct population, and they are considered critically endangered with only an estimated 74 individuals left.
There are also few new births occurring to replace individuals that have died. In fact, only around two-thirds of pregnancies come to term. There were several reported pregnancies in September 2018 but no calf sightings from those pregnancies.
However, 2019 began with some positive news. A calf was born to L77, reported The Seattle Times. The Center for Whale Research first spotted the calf on Jan. 11 and said it appears to be a few weeks old. However, they caution that the calf is still vulnerable and may not survive to adulthood given the whales' survival rate. The whales haven't been able to successfully reproduce in three years.
The reason Southern Resident orcas can't successfully reproduce confused researchers until a couple years ago. Using dogs trained to track down orca scat, the researchers collected scat samples for six years. In 2017, they analyzed the DNA and hormones held within the 350 samples gathered over the years and the results were published in PLOS ONE. The culprit is food scarcity.
"Low availability of Chinook salmon appears to be an important stressor among these fish-eating whales as well as a significant cause of late pregnancy failure, including unobserved perinatal loss," noted the study authors, which included Sam Wasser, founder of the Conservation Canines program of the Center for Conservation Biology at University of Washington which provides the scat-sniffing dogs so important to the research.
"However, release of lipophilic toxicants during fat metabolism in the nutritionally deprived animals may also provide a contributor to these cumulative effects. Results point to the importance of promoting Chinook salmon recovery to enhance population growth of Southern Resident killer whales," the authors wrote.
The problem comes down to not enough food, and as females burn what fat stores they have during pregnancy, they release toxins that are then absorbed by the fetus. How much of each factor drives the failure of pregnancies is still unclear.
The number of Southern Resident orcas has been dropping for years. Recently, the Center for Whale Research announced that two orcas are failing in health and likely will die by this summer due to malnutrition. In January 2019, The Seattle Times reported that the center spotted a 42-year-old female orca named J17 with a "peanut-shaped" head, a misshapen head and neck caused by starvation. Also, a 27-year-old male orca named K25 is in poor health because he can't properly forage for his own food after his mother died in 2017.
But what is obvious is that as the salmon disappear, it's only a matter of time before the orcas disappear too.
"Many species of Chinook salmon along are listed as threatened or endangered due to factors including loss of habitat from urban development, dams, fishing, pollution and competition from non-native fish," reported The Washington Post. "[I]mproving those Chinook salmon runs could help save Puget Sound orcas. Reducing pollution and other factors could increase the number of salmon, providing orcas with more food."
In other words: Save the Chinook, save the Southern Resident orcas.
Editor's note: This article has been updated since it was originally published in July 2017.