Boat speed is a big problem for Puget Sound’s endangered killer whales,
published Wednesday.
The number of whale-watching vessels in Washington and British Columbia has more than quadrupled since the 1980s. At times, killer whales, or orcas, will be tailed by more than 20 boats when they enter Puget Sound and the Salish Sea.
“Of all the characteristics that we examined, vessel speed was the most important factor for how loud it was for the whales,” said Juliana Houghton, lead author of the paper, which was just published in the journal PLOS One.
Vessel traffic and noise are one of the main threats to Puget Sound’s resident killer whales, which now number about 80 animals. Previous studies have shown that Southern Resident killer whales raise the volume of their calls and change their behavior when vessels are present. The Whales call and echolocate to communicate with one another and find food.
Houghton analyzed hydrophone recordings from suction tags that were attached to more than 20 orcas over the past several years. She took the volume levels in the recordings and lined them up with the numbers of boats that were nearby at the time. She also recorded the size of the boats, how many propellers they had, and the speed they were traveling.
Watch video of the orca tagging operation:
Currently, federal regulations require that boats stay 200 yards away from orcas, but boaters aren’t subject to any specific speed limits when whales are nearby.
The National Oceanic and Atmospheric Administration, which funded the research in partnership with the University of Washington, said the new research will be taken into consideration when the administration weighs the possibility of new regulations on speed limits for boats near orcas.
The hydrophone recordings for the study were gathered from 2010 to 2012.
EarthFix featured the orca tagging operation in 2012. Here is producer Ashley Ahearn’s reporter’s notebook account of the trip:
FRIDAY HARBOR, Wash. -- We catch up with the orcas a few minutes after we leave the dock. They’re near Rosario Strait in the San Juan Islands.
Their sharp dorsal fins pierce the smooth golden-blue-autumn water around us. Representatives from all the pods: K30 off in the distance. L23 closer in. There rises L84, an imposing 20-year-old male.
Getting a suction tag onto a 5-ton orca can be tricky, but the scientific rewards are big. Scientists are using the devices to gather underwater data about orca behavior to find out how vessel traffic might be affecting the endangered whales.
Ashley Ahearn, KUOW/EarthFix (all photos collected under NMFS ESA Scientific Research Permit #16163)
His rounded black head pierces the surface, then his body – a giant barrel of muscle and blubber – rolls into sight above the waves. Then he dives.
He surfaces closer to the boat — a Zodiac loaded down with a team of five scientists from the National Oceanic and Atmospheric Administration — and exhales a loud misty breath. I gasp, too.
The animal instinct somewhere deep in my brain is terrified for a moment, before I remind myself that 1) I am in a boat and 2) This whale not only prefers salmon to any other fish (or human) but he can specifically pick out chinook salmon, and regularly picks them out of fishy lineups when hunting. I am safe. I am clutching my microphone, desperate to capture this moment.
Jeff Hogan is on the bow holding a long pole, a sort of modern-day harpoon. But instead of anything sharp or pointy at the tip there is a flat yellow device about the size of your hand. One side is lined with octopus-looking suction cups. On the other, a tiny antennae.
It’s called a D-tag and Jeff Hogan has to get it to stick on to L84’s back the next time he surfaces.
Once it’s attached, the D-tag will track the movement of the whale through the water. The goal is to learn more about how all the boats traveling through Puget Sound might be affecting orca behavior.
Suddenly L84 surfaces again, feet from the bow, where Hogan stands ready with the long pole.
“Ok, here we come up right here,” he exclaims.
In the blink of an eye the man stretches over the bow, like a pitcher on the mound, and extends the pole to place the tag on L84’s back, just before the whale dives again.
“Tag is on!” the crew exalts. The device has suctioned on to L84’s blubber, without a scrape. The whale seems unfazed and goes back to foraging.
Studying whales requires a lot of patience because you can spend hours waiting for a five second glimpse of these creatures. Scientists don’t know much about what goes on underwater.
But that’s exactly why the D-Tag research is so exciting. It allows scientists to “spy” on orcas deep beneath the waves.
As L84 dives the D-tag is collecting data about his depth, the direction he’s moving – even the angle of his body.
But perhaps most excitingly, it’s collecting audio, recorded on a tiny hydrophone inside the tag.
All of this information is helping whale experts figure out not only what these whales are doing when they’re underwater, but how their surrounding environment might be affecting them. Are the whales foraging less? Are they socializing less? Resting for shorter periods?
From the bow, Deborah Giles, an expert on orca behavior and vessel traffic, keeps a lookout for the tagged whale. She’s holding a device that looks like the tool engineers use to survey plots of land for construction projects. It’s called a laser range finder and it will synch up with L84’s tag the next time he comes up, logging his location. Giles aims it at the bubbles on the surface that signal L84’s imminent arrival.
“Basically what I’m recording is where the whale is on the planet,” Giles explains, “and that allows me to get distances from whales to boats.”
When the scientists get back to shore they’ll create a simulation of the dive – almost like a video game of L84 as he moves.
But here’s the cool part: The scientists will eventually correlate L84’s movements with the coordinates and sizes of the surrounding boats – and there are quite a few boats at this point.
Watch video from another tagging session on orca K33:
It's about 11 o'clock. And that means the pleasure cruisers and whale watch tours are out. The team takes note of a passing naval cruiser and an oil tanker and adds it to the log.
Heading underwater here for a sec: picture the sonic "view" from L84's perspective. You're diving and surfacing, diving and surfacing. You find a sparkling chinook salmon darting through the water and give chase. The fish moves into the deep, dark waters of Puget Sound and you use your echolocator to track him, but the low rumble of motor engines are echoing in your head as well.
Orcas "see" underwater by emitting a series of clicks that bounce back off of their prey. They can tell the difference between a chinook salmon and a coho or a chum. (Yes, they're that good.)
But if orcas use sound to "see," the droning background noise of a ship's engine would be kind of like putting on sunglasses and then trying to go chase your dog in the woods at night.
Hundreds of tankers, whale-watching boats, pleasure cruisers and military vessels travel through orca habitat. One proposal to build a coal export terminal on the coast near Bellingham could add up to 500 more large ships a year. Scientists believe the orcas hear this traffic, and it could be a problem for them.
"It's a valid assumption to say that when you add more boats you're going to add more noise to the ocean," says Marla Holt, an expert on marine mammals and acoustics at NOAA's Northwest Fisheries Science Center in Seattle.
"But at what level would they just not be able to compensate - where it's just so loud, no matter how loud they "shout" that it's not going to matter?" she asks. "Those are the types of things that are really concerning."
For now, scientists don't know exactly how disruptive this underwater noise is for the orcas, but being able to correlate whale movement with vessel size and proximity will provide key information that could influence future protection and recovery strategies for these endangered whales.