Scientists Unlock The Secrets (And Sounds) Of Orcas Underwater

Oct 3, 2012

If you’re a resident killer whale Puget Sound can be a busy and noisy place.

Some research shows that during the summer tourist season - when the orcas come into Puget Sound most regularly - they can be surrounded by an average of 20-25 boats.

Scientists are trying to figure out how pleasure boats and larger vessels may be affecting the behavior and recovery of this endangered species.

We get word that the whales are nearby soon after leaving the dock at Friday Harbor Labs on San Juan Island.

Brad Hanson (on radio): “Yeah we just got a report that the whales are in Bellingham Channel.”

Brad Hanson is an expert on orcas with the National Oceanic and Atmospheric Administration in Seattle. “Ok, we’re going to run over there.”

The zodiac takes off, packed with gear and scientists. Their mission is a tricky one. They’re going to try and attach a high tech data collection device to a moving orca.

It’s called a Dtag and it’s about the size of your hand. One side’s lined with small suction cups that will stick onto the whale’s back.

Once it’s attached the Dtag will track the movement of the whale through the water. The goal is to learn more about how all the boats travelling through Puget Sound might be affecting orca behavior. Are they foraging less? Are they socializing less?

We come around Lopez Island heading to Rosario Strait and there are orcas all around us. The research vessel slows way down as the team gets ready.

We encounter several pods of orcas near Lopez Island.
Credit Ashley Ahearn / Earthfix

Now comes the easy part. All they have to do is get the tiny Dtag stuck to the back of a 5-ton whale - a whale that’s moving rapidly through the water on the hunt for salmon.

Jeff Hogan is the lucky guy in charge of that part of the operation. He’s standing in the bow of the boat holding a long pole with the Dtag attached to the end. The whales are just meters away. "Underwater here at a our 4 at 20."

Hogan will throw the pole at a whale so the suction device can stick on to the whale’s back. His set up is harmless, but effective - Picture a cross between a harpoon and a kid’s nerf toy.

The team has picked out a large adult male they identify as L84. Suddenly he surfaces right next to the boat and Jeff Hogan seizes his moment. "Ok, here we come up right here."

Hogan throws the pole at the whale. "Tag’s on. He’s back over here. He’s at our 11. 10 and 11."

The tag sticks and L84 goes right back to hunting for salmon. Deb Giles steps up to the bow. She’s an expert on orca behavior and vessel interaction. "I'm ready."

Giles is holding a device on a tripod that looks like something a land surveyor uses on construction sites. It’s called a laser range finder.

She’s aiming it at the place where L84 last surfaced, waiting for him to come up again. “Basically what I’m recording is where the whale is on the planet, and that allows me to with this equipment to get distances from whales to boats.”

The tag should stay stuck on the whale for the next 6 hours or so, and in that time massive amounts of location and movement data will be recorded.

And get this, the tag has a hydrophone in it. It will record what the whale is hearing as it dives.

"They’re communicating periodically, 'Hey are you there?' 'Yes I’m still here.'” Marla Holt studies acoustics and marine mammals at NOAA’s Northwest Fisheries Science Center. “You can hear some loud calls and some soft calls so you get the sense that there was a call that was produced by the tagged whale and then other of its family members responded by calling back, basically.”

What happens if there’s a big boat in the background? “If there’s a big boat in the background what happens is the noise emitted by the boat, by the motor of the boat," Holt says, "can make it harder for the animals to hear those distant calls.”

Tankers like this one produce underwater noise.
Credit Ashley Ahearn / Earthfix

And that forces the whales to call more loudly. But orcas don’t just use sound to talk to each other under water. It helps them see. The use echolocating clicks to locate their prey, the same way bats hunt using sonar.

For an orca, having a lot of background noise, like the drone of a tanker engine for example, would be sort of like if you tried to find your dog in the woods at night… wearing dark sunglasses.

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.

Holt says 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. … 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. So those are the types of things that are really concerning.”

The scientists have hours and hours of underwater recordings and whale GPS coordinates to analyze. Holt and the rest of the team say it’s too soon to directly link any specific whale behavior with specific vessels that travel through Puget Sound, but with more data, patterns in orca behavior and ship traffic will emerge.

At this point the underwater lives of orcas are largely a mystery to scientists, but gaining access might be the key to protecting this endangered species.

Copyright 2012 Earthfix