After the death of a 23-year-old orca June, the total number of southern resident killer whales is down to 75, the lowest it's been since the early '80s. This orca mother has been holding her dead calf afloat for more than a week in a "heartbreaking" ritual.<br><br>Read more at <a href="https://t.co/LPrUsQCzDj">https://t.co/LPrUsQCzDj</a> <a href="https://t.co/FgsHnWrgTw">pic.twitter.com/FgsHnWrgTw</a> —@CBCNews 
 
 Their decline is attributed largely to a lack of available chinook salmon, their primary food source.
– An orca who spent more than a week carrying her calf following its July 24 death now has some help. Other orcas in the pod swimming through Pacific Northwest waters near the US-Canada border are taking turns carrying the corpse after the effort caused the 20-year-old mother known as J35 to fall behind with labored breathing. Trailing the main pod with improved breathing, J35 was seen with the now-decomposing corpse Thursday in the Strait of Juan de Fuca alongside immediate family members who are keeping her fed, per KCPQ. But "because we've seen her so many times without the calf, we know that somebody else has it," Jenny Atkinson of San Juan Island's Whale Museum tells the CBC. The same pod held a similar display 15 years ago, but this is the longest period of orca mourning on record, per National Geographic. Audio recordings indeed suggest the pod is using calls and whistles perhaps related to mourning. They sound "more like a very urgent call," says Atkinson. "I think that what you're seeing is the depth of importance of this calf and the grief of the mother and the family." It's a tight-knit one: There are just 75 orcas in three pods in the southern resident population around Oregon, Washington, and Vancouver Island, down from 83 in 2016. None have seen a successful birth since 2015. Amid indications a 4-year-old orca might be starving, an expert describes "at most five more years" in which to try to birth viable offspring. Declines in Chinook salmon have hit the population hard, per Nat Geo. Canada hopes to lend a hand by limiting catches of the fish, while experts hope a necropsy will reveal how J35's calf died, per CTV News. Of course, it must be abandoned first.