It’s been a killer year for an endangered orca pod off British Columbia’s coast.
Another whale was born to the southern resident population, bringing the annual birth rate up to eight—a number that hasn’t been seen in nearly four decades. The Centre for Whale Research says they haven’t seen a baby boom like this since 1977, when nine calves were born. In more recent years, the birth rate has averaged at around three calves per year.
The newborn whale was first spotted on December 1 near the San Juan Islands and Vancouver Island. Last week, the researchers managed to snap a photo to confirm it wasn’t another one of the calves born this year.
And while it’s being referred to as a “boom,” Michael Harris, the director of the Pacific Whale Watch Association, told CBC News that the latest calf actually just puts the birth rate back on track.
Based on calculations that take all female orcas of reproductive age into account, researchers estimate that if conditions are optimal, up to nine babies could be produced each year.
But not only is this isolated population of whales genetically and culturally distinct, they also have a very distinct diet, made up of almost entirely chinook salmon.
Dwindling salmon stocks and global warming are said to be major contributors to the previously low birth rates, and researchers warn that these factors could affect the whales’ long-term survival as well.
An adult whale can eat up to eight large chinook salmon every day, and they often have to travel multiple kilometres for each fish.
“Warmer ocean waters are less productive, and rivers without continual water from snow melt (rains run off too quickly) and with warmer water are lethal to salmon,” Harris told CBC News. “In the years immediately following poor salmon years, we see fewer babies and higher mortality of all age cohorts.”
That means, despite the good news, the survival of these whales, both young and old, depends on a plentiful stock of Chinook salmon in the northeastern Pacific Ocean ecosystem.