Right Whales Under Stress Mean Fewer Calves
They’re hard to miss when you walk into the New Bedford Whaling Museum: four enormous whale skeletons suspended from the ceiling, nearly filling the 2-story space. There’s a humpback whale and a blue whale, but what catches most peoples’ eye is a pair of whales: a female North Atlantic Right Whale, and her calf—also a female.
The mother and calf were killed by a ship strike off Virginia in 2004. The mother was just 15 years old; her baby, still forming inside her, was just ten months old.
Museum education director Robert Rocha hopes visitors—like this group of 3rd graders—see the pair and are inspired to protect and conserve whales.
“I think it’s a pretty powerful statement both as to how big and how impressive the animals are,” Rocha said, “But [it also shows] how fragile they are when it comes to interacting with things we put in the water.”
This museum could one day be the only place to see a North Atlantic Right Whale mother and her calf together. So far this year, there have been no new right whale births recorded. That’s not good for a species that sustained 17 deaths last year. Two of those deaths were younger females who might have reproduced later—and scientists think there are only about 100 breeding female right whales left in the world.
New England Aquarium Research Scientist Philip Hamilton says years of fishing gear entanglements, ship strikes, noise and chemical pollution—even climate change—are taking a toll on female right whales. Fewer females reached reproductive age over the last few years, and of those that did, fewer gave birth than they had in the past.
“We’ve never had no calves seen by this point in the year,” Hamilton said. “The reproductive females are our hope, so each one that is lost is not just an individual, it’s the potential of hundreds of individuals, literally.”
Take an entanglement, for example. Rosalind Rolland, Director of Ocean Health at the New England Aquarium’s Cabot Center for Ocean Life, says fishing gear can do far more than the visible injuries we see; it can cause long-term damage to a whale’s heart and immune system, it could make a whale susceptible to disease; it can even slow down or stop the reproduction process.
“We know that whales undergo chronic entanglements, and these entanglements can last months and even years,” Rolland said. “Their stress hormones are off the scale. These whales are in extreme physical distress.”
That stress, coupled with other injuries from an entanglement, could prevent a whale from giving birth, or a pregnant female could miscarry. And it’s highly likely a whale has been entangled at least once in her life—some 80 percent of the population has been caught in fishing gear.
Rolland monitors hormone levels throughout the entire whale population using whale fecal samples, among other things.
She takes me to her lab upstairs in the Aquarium where her assistant pulls out a frosty jar from a freezer; the bright-orange droppings inside contain clues about the animal’s diet, overall health, and even its reproductive status.
“They’re really a treasure chest of information about a really hard-to-study animal,” Rolland said.
Rolland can see stress hormone spikes. She can also detect reproduction hormones—or their absence.
“We see each individual whale so frequently that we know completely accurately between the years between calving,” she said.
But other causes for the decline in whale births, like food scarcity, are harder to diagnose. New England Aquarium Research Scientist Philip Hamilton says warming ocean water could be to blame for the whales shifting from the Bay of Fundy to the Gulf of Saint Lawrence in the summer.
“We do know that the Gulf of Maine is warming faster than almost any other body of water in the world,” he said. “It’s basically wreaking havoc on the center of their feeding grounds.”
That shift could make it even tougher for females; they fatten up before swimming south to give birth and nurse. If they are stressed from injury or illness, Rolland said, it could be even harder for them to make it north again to feed and restore their blubber as they prepare to reproduce again.
“I think it’s important to remember there’s more than one possible cause here, and we [sometimes] don’t have the techniques to pursue those and rule them out,” she said.
Though Hamilton, Rolland, and other scientists we’ve talked to for this series said that while the prognosis is grim for right whale survival, all hope is not lost—we can still do something about it. For one thing, a lot of people are focused on this animal, Rolland said.
“This population is so well-known, it’s followed from birth to death by researchers all up and down the East Coast,” she said.
Her hope is that with all those eyes—and minds—keeping track of the right whales, we’ll come closer to finding a way to keep them alive and thriving in the ocean, and out of the history museum.
This is the second installment of our special reporting series on right whales called, "In the Shadow of Extinction."