Beam Reach

Hydrophone calibration

Thursday, September 13, 2007

We woke up to a thick fog bank off Snug Harbor and scrambled eggs prepared by Ashley. We finished up our post-breakfast chores and sat down to voyage planning for the day. Our pager alerts informed us that no killer whales had been spotted, so we decided to calibrate all of the hydrophones. We lowered the hydrophones tied together like a bunch of bananas off the port side, and a speaker off the starboard. Alex, Tim, and Ashley recorded tones at various gains. Todd prepared homemade mayonnaise for an egg salad that Sam and Shannon whipped up for lunch. After lunch and coffees all around, the students began analyzing preliminary data. In the afternoon, Gato Verde headed out of Snug Harbor and Tim hoisted the main for a bit of sail training. We deployed the hydrophones again and recorded a passing steamer and ferry while collecting data on range, latitude, and longitude. After practicing jibes and chicken jibes, we headed north for Stewart Island and secured a mooring buoy in Redi Harbor. After a very refreshing sunset swim, we sat down to a Greek meal of briam cooked by Alex.

First-ever localization of mother/calf calls

First ever mother/calf recording!

An amazing scientific feat was accomplished during the first sea-week of the fall 2007 program. At the end of the first deployment of our hydrophone array, a mother and calf were recorded vocalizing on the west side of San Juan Island. While orca calves rarely leave their mother’s side, this calf seemed adventurous. It left its mother and another female foraging along a tidal front, approached the hydrophone array we were towing, made an underwater turn to parallel our heading, surfaced close off our port bow, and then diverged from our course to rejoin its mother.Luckily, the Beam Reach team was already effectively collecting data when this rare mother/calf separation occurred. Most of us were watching and listening carefully enough to remember the course of events. Todd was helping Sam take bearings on the orca calf with a hand-held compass and Shannon was taking photographs to help identify the whales. I was writing down the bearings and GPS-synchronized times, noting when good calls were heard (listening through the deck speakers). Val’s computer was recording the data from each of the four hydrophones in the array. Mike was doing a good job of being Whale Wise and maintaining a steady heading (to keep the array straight).

When the array data were analyzed with software that allows us to “localize” sounds recorded on all four hydrophones, the locations of the calls corresponded well with the visual bearings Sam took and the general sequence of events we all remember (and wrote down). This is remarkable because we have struggled for two years to get all of the technologies functioning together. Courtney (2005) and Peggy (2006) will certainly appreciate how lucky we were to have the ability to localize the calls that were made during this unusual mother/calf interaction.

The localization results tell us a lot. It is clear that the calf’s calls are interspersed with the calls of the two nearby adults (mother or brother). This is the first documented call/response interaction of southern resident killer whales! While we have long suspected that the residents call and respond to each other, it isn’t clear which animal makes which sound when listening through a single hydrophone. The array enables us to learn that different animals are making the calls. It also allows us to assign particular calls — and even voices — to specific individuals. So, now we know what one calf’s call sounds like, and we have an opportunity to compare its voice with its mothers voice. This is a fledgling, but critical, first step to voice-recognition in the southern residents. A final breakthrough is being able to visualize the trajectory of the calf underwater. By combining such “passive localization” techniques with acoustic fish tags and bleeding-edge 3-D active sonar technologies (at frequencies above killer whale hearing), we will soon be able to observe how the whales navigate within their complex ecosystem and interact with other animals, their prey, plankton, and the rest of the environment.

So, the fall 2007 program has already made a great technological leap. Congratulations all around! Let’s hope the Beam Reach class continues to have such great luck. Clearly, we are poised to learn a lot more about the southern residents this year with the array system.

Recollections from a week at sea

I recently had the wonderful opportunity to join the Beam Reach students at sea for a week. Thanks to my wife, Annie, and my mother, Leslie, I was able to step away from being a dad for a while and return to the equally intense experience of conducting field science at sea and thinking hard with a talented group of students and teachers.

I’ll blog in more detail about some of the highlights from my week, but first I want to offer a few photos, recollections, and associated vignettes:

• The excitement I felt when hearing orca calls on the radio while 1/2 mile offshore. All visitors to the west side of San Juan Island should know that underwater sound is broadcast live on FM radio station 88.1 MHz. We had lost track of the southern residents (they often seem to “disappear” when you least expect it), so for the first time I really benefitted from the FM transmitter atop the Lime Kiln State Park lighthouse. While scanning Haro Strait with the binoculars, I was surprised to hear clear calls from Lime Kiln where the hydrophone is just 10m offshore and 8m down. Focusing on that part of the shoreline, I could see tourists concentrated in front of the rising fins of orcas. The residents had surfaced right next to shore and were nigh impossible to see against the dark metamorphosed basalt of the Island’s coastline. Note: the FM transmitters have a range of a couple kilometers and a second one is located about a kilometer south of Smuggler’s Cove (at Val’s house, known as OrcaSound).
• We should be helping Soundwatch and Straitwatch educate boaters. After watching a big cruiser violate the voluntary 1/2 mile no-go zone around Lime Kiln lighthouse, paralleling the whales <100m off the Lime Kiln shoreline right in front of hundreds of tourists, I decided Beam Reach should take a more active role in educating boaters about how to be Whale Wise. In the past, I’ve leaned towards measuring first, and educating later. But with the Soundwatch vessel’s engines disabled by a bad head gasket and the Straitwatch vessel already over-burdened, why shouldn’t the Beam Reach staff and students (not to mention Whale Watch captains/naturalists) by hailing such boats on VHF channel 16 to ensure the Captains know the voluntary (soon to be mandatory) boating regulations? Perhaps we could/should also broadcast hydrophone signals from the boat on a VHF or FM channel for the whale watching, recreational, and fishing fleets? [Whoa, another service project.]
• Trying to let Wessal push her limits, but also avert disaster. There’s no question that Wessal is gung ho. I don’t know if it’s because she has relatives who are boat mechanics, or what, but when she took hold of the outboard engine on the Gatito (Gato Verde’s tender), she showed no fear. She did a great job of maneuvering through the kelp to grab some supplies that Val handed us from shore, but on the way back she got up on a plane and inspired me to (again) find the boundary between teaching by inquiry (like a good Beam Reach instructor) and mitigating risk (like a good Beam Reach administrator). Picture my left hand clutching the seat in front of me, my right poised surreptitiously just above hers, the tiller, and the too-sensitive throttle. I don’t know if she noticed my white knuckles as I tried to stay present and enjoy the ride while worst case scenarios skittered and cartwheeled through my imagination.
• The joy of not shaving for a week. My grad school advisor, Russ McDuff, instilled this oceanographic tradition in me. I shaved it off the night I got back to civilization, but I enjoyed the rare pleasure of growing a pirate’s countenance.
• Falling asleep listening to leopard seals recordings.
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• The stunning beauty of the Pacific Northwest — the sunsets, water textures, and mountain range silhouettes

There are many more memories, but those are my favorites. It was a pleasure meeting all of the 071 students in person at last. I look forward to another week-long immersion this Sept 26 – Oct 3!