It's a girl! Why the newest orca calf's gender is so important

SAN JUAN ISLANDS, Wash. -- The newest southern resident orca calf is reportedly fat and healthy, but that's not the only news researchers are celebrating: She's also female.

It's a great sign for the dwindling population that has seen far more male calves than females in recent years.

"If she makes it her teens she might start producing babies of her own," said Ken Balcomb of Center for Whale Research. "Unfortunately, none of them made it recently to their teens."

Balcomb, looking at a photo of the new calf known as J56, indicated that the endangered population is obviously trying to repopulate.

While the population has more than 70 whales, he said only about a third of them are of reproductive age. Of those, only five have proven to successfully reproduce.

If J56 continues to be a viable calf, her mom, J31, will make six reproductive whales. Researchers know J31 has been pregnant at least one other time. In 2016, she gave birth to a stillborn calf.

Samuel Wasser of University of Washington's Conservation Biology said the most likely hypothesis for the skewed sex ratio in southern resident calves is inbreeding.

If there is too much inbreeding, the embryo is too genetically similar to the mother and there isn't a strong implantation response. About 70 percent of pregnancies fail in the population.

"The reason that tends to create a male bias is because, all else being equal, males are more different to the mom than are females because males have a y chromosome," Wasser said. "What that means is that when you do get conceptions under this time you're more likely to make boys. And that means you're just cooked."

It's why J50, or Scarlet's, death last year was even more devastating. Researchers had hoped the three-and-a-half-year-old female would grow up to be a mom.

Researchers have not yet identified the sex the other new calf in L pod, L124.