Orca that carried dead calf for 17 days is pregnant again

J35, sometimes called Tahlequah, attracted worldwide attention in the summer of 2018

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      The orca that generated sympathy worldwide two summers ago when it held its dead calf above water for 17 days while it swam an estimated 1,600 kilometres is pregnant again.

      Photos taken recently by drone show, when compared to pictures taken remotely last fall, that J pod orca J35 appears to be pregnant. Orca pregnancies typically last about 18 months.

      On July 24, 2018, J35 (sometimes called Tahlequah) gave birth to a calf that died within a few hours. Shortly after, J35 was observed balancing the dead calf above water with her nose while she swam, a behaviour described by some researchers as a grief reaction and one that is sometimes seen among orcas for a day or so after neonate deaths.

      The then-20-year-old female's pregnancy and birth had been the first in three years among the three endangered pods (J, K, and L) that form the so-called southern resident orca population. Since then, there have been two successful births in the group, one each in K and L pods. (In 2010, J35 successfully gave birth to a male calf, J47.) 

      J35 carrying her dead calf in 2018.
      Taylor Shedd/Soundwatch

      During the 16 days following the calf's death, observers saw J35 swimming with the body in various locations in the Salish Sea, off southern Vancouver Island and southwestern B.C. and the coastal northwest of the state of Washington.

      At the time, Ken Balcomb, senior scientist at the Friday Harbor-based Centre for Whale Research (CWR) on San Juan Island, told media outlets: ""We've seen mother whales carry dead babies briefly, for parts of a day. We saw one a few years back for a couple days. But this sets a record."

      An August 11, 2018, CWR update announced the end of J35's "tour of grief" and pronounced the orca "remarkably frisky".

      The southern resident population of orcas (Orcinus orca, often called killer whales) live in and travel throughout the Salish Sea. The  Salish Sea comprises major water bodies the Strait of Georgia, Juan de Fuca Strait, Puget Sound, and connecting waterways, wherein are found the San Juan Islands and the Gulf Islands, in the U.S. and B.C., respectively.

      The recent noninvasive drone pictures were taken and analyzed by reearchers John Durban, senior scientist of Southall Environmental Associates, and Holly Fearnbach, marine mammal research director for the nonprofit Washington state-based SR3 (SeaLife Response, Rehabilitation, and Research).

      A pregnant J41 from J pod chases a salmon.
      SR3 (SeaLife Response, Rehabilitation, and Research)

      According to the Seattle Times, the two scientists' research is part of an ongoing and long-term study of southern residents' physical condition. Scientific consensus is that the precipitous decline of chinook salmon (southern resident orcas' principal food source) in the Salish Sea is responsible—along with large volumes of intrusive and noisy marine traffic and the bioaccumulation of persistent organic pollutants (POPs)—for the population decline and low birth rate of the endangered marine mammals in recent decades.

      Southern resident orcas were listed as endangered by Canada in 2001 and by the U.S. in 2005.

      Northwest Fisheries Science Center research vessel Noctiluca studying southern resident orcas.

      A study of southern residents by University of Washington researchers, published in PLOS One in June 2017, found that almost 70 percent of detectable pregnancies between 2008 and 2014 were unsuccessful, with a third of them failing late in gestation or immediately after birth. "Low availability of chinook salmon" was determined to be the major factor in the southern residents' stalled reproductive rate.

      Research into underwater noise from marine traffic—both commercial, private, and naval—in southern residents' prime living and hunting territories has found it to have a negative impact on their abilities to communicate, navigate, and use echolocation to find food. This has been acknowledged by Fisheries and Oceans Canada. An increase in ferry, freighter, cruise-ship, and oil-tanker traffic in recent decades has made the problem worse, with some estimates having the disruptive noises doubling every decade since the 1980s.

      A 2017 study commissioned by the Port of Vancouver found that marine-traffic noise contributed to up to a 23 percent reduction in daily foraging time for orcas.According to the CWR, adult orcas require as many as 25 fully grown salmon every day.

      The December 31 southern resident population update by the CWR (an estimate only) set the group number at 73 orcas of all ages, broken down to 22 for J pod (whose members are most frequently seen by B.C. and U.S. residents and tourists in the Salish Sea), 17 in K pod, and 34 for L pod. In 2006, the three pods' combined population was estimated at 89.

      According to CWR, southern-resident captures for marine-park exhibits in the 1960s and 1970s resulted in at least 13 orca deaths and 45 pod members shipped to international destinations.