Coastal oceanography takes patience

Joe Haxel, Acoustician, Assistant Professor, CIMRS/OSU

Greetings GEMM Lab blog readers. My name is Joe Haxel and I’m a close collaborator with Leigh and other GEMM lab members on the gray whale ecology, physiology and noise project off the Oregon coast. Leigh invited me for a guest blog appearance to share some of the acoustics work we’ve been up to and as you’ve probably guessed by now, my specialty is in ocean acoustics. I’m a PI in NOAA’s Pacific Marine Environmental Laboratory’s Acoustics Program and OSU’s Cooperative Institute for Marine Resources Studies where I use underwater sound to study a variety of earth and ocean processes.

As a component of the gray whale noise project, during the field seasons of 2016 and 2017 we recorded some of the first measurements of ambient sound in the shallow coastal waters off Oregon between 7 and 20 meters depth. In the passive ocean acoustics world this is really shallow, and with that comes all kinds of instrument and logistical challenges, which is probably one of the main reasons there is little or no acoustic baseline information in this environment.

For instance, one of the significant challenges is rooted in the hydrodynamics surrounding mobile recording systems like the drifting hydrophone we used during the summer field season in 2016 (Fig 1). Decoupling motion of the surface buoy (e.g., caused by swell and waves) from the submerged hydrophone sensor is critical, and here’s why. Hydrophones convert pressure fluctuations at the sensor/ water interface to a calibrated voltage recorded by a logging system. Turbulence resulting from moving the sensor up and down in the water column with surface waves introduces non-acoustic pressure changes that severely contaminate the data for noise level measurements. Vertical and horizontal wave motions are constantly acting on the float, so we needed to engineer compliance between the surface float and the suspended hydrophone sensor to decouple these accelerations. To overcome this, we employed a couple of concepts in our drifting hydrophone design. 1) A 10 cm diameter by 3 m long spar buoy provided floatation for the system. Spar buoys are less affected by wave motion accelerations compared to most other types of surface floatation with larger horizontal profiles and drag. 2) A dynamic shock cord that could stretch up to double its resting length to accommodate vertical motion of the spar buoy; 3) a heave plate that significantly reduced any vertical motion of the hydrophone suspended below it. This was a very effective design, and although somewhat cumbersome in transport with the RHIB between deployment sites, the acoustic data we collected over 40 different drifts around Newport and Port Orford in 2016 was clean, high quality and devoid of system induced contamination.

Figure 1. The drifting hydrophone system used for 40 different drifts recording ambient noise levels in 7-20 m depths in the Newport and Port Orford, OR coastal areas.













Spatial information from the project’s first year acoustic recordings using the drifting hydrophone system helped us choose sites for the fixed hydrophone stations in 2017. Now that we had some basic information on the spatial variability of noise within the study areas we could focus on the temporal objectives of characterizing the range of acoustic conditions experienced by gray whales over the course of the entire foraging season at these sites in Oregon. In 2017 we deployed “lander” style instrument frames, each equipped with a single, omni-directional hydrophone custom built by Haru Matsumoto at our NOAA/OSU Acoustics lab (Fig. 2). The four hydrophone stations were positioned near each of the ports (Yaquina Bay and Port Orford) and in partnership with the Oregon Department of Fish and Wildlife Marine Reserves program in the Otter Rock Marine Reserve and the Redfish Rocks Marine Reserve. The hydrophones were programmed on a 20% duty cycle, recording 12 minutes of every hour at 32 kHz sample rate, providing spectral information in the frequency band from 10 Hz up to a 13 kHz.

Figure 2. The hydrophone (black cylinder) on its lander frame ready for deployment.

Here’s where the story gets interesting. In my experience so far putting out gear off the Oregon coast, anything that has a surface expression and is left out for more than a couple of weeks is going to have issues. Due to funding constraints, I had to challenge that theory this year and deploy 2 of the units with a surface buoy. This is not typically what we do with our equipment since it usually stays out for up to 2 years at a time, is sensitive, and expensive. The 2 frames with a surface float were going to be deployed in Marine Reserves far enough from the traffic lanes of the ports and in areas with significantly less traffic and presumably no fishing pressure.  The surface buoy consisted of an 18 inch diameter hard plastic float connected to an anchor that was offset from the instrument frame by a 150 foot weighted groundline. The gear was deployed off Newport in June and Port Orford in July. What could go wrong?

After monthly buoy checks by the project team, including GPS positions, and buoy cleanings my hopes were pretty high that the surface buoy systems might actually make it through the season with recoveries scheduled in mid-October. Had I gambled and won? Nope. The call came in September from Leigh that one of the whale watching outfits in Depoe Bay recovered a free floating buoy matching ours. Bummer. Alternative recovery plans initiated and this is where things began to get hairy. Fortunately, we had an ace in our back pocket. We have collaborators at the Oregon Coast Aquarium (OCA) who have a top-notch research diving team led by Jim Burke. In the last week of October, they performed a successful search dive on the missing unit near Gull Rock and attached a new set of floats directly to the instrument frame. The divers were in the water for a short 20 minutes thanks to the good series of marks recorded during the buoy checks throughout the summer (Fig. 3).

Figure 3. OCA divers, Jenna and Doug, heading out for a search dive to locate and mark the Gull Rock hydrophone lander.






We had surface marker floats on the frame, but there was a new problem. Video taken by Jenna and Doug from the OCA dive team revealed the landers were pretty sanded in from a couple of recent October storms (Fig. 4). Ugghhh!

Figure 4. Sanded in lander at Gull Rock. Notice the sand dollars and bull kelp wrapped on the frame.

Alternative recovery plan adjustment: we’re gonna need a diver assisted recovery with 2 boats. One to bring a dive team to air jet the sand out away from the legs of the frame and another larger vessel with pulling power to recover the freed lander. Enter the R/V Pacific Surveyor and Capt. Al Pazar. Al, Jim and I came up with a new recovery plan and only needed a decent weather window of a few hours to get the job done. Piece of cake in November off the Oregon coast, right?

The weather finally cooperated in early December in-line with the OCA dive team and R/V Pacific Surveyor’s availability. The 2 vessels and crew headed up to Gull Rock for the first recovery operation of the day. At first we couldn’t locate the surface floats. Oh no. It seemed the rough fall/ winter weather and high seas since late October were too much for the crab floats? As it turns out, we eventually found the floats eastward about 200 m but couldn’t initially see them in the glare and whitecapping conditions that morning. The lander frame had broken loose from its weakened anchor legs in the heavy weather (as it was designed to do through an Aluminum/ Stainless Steel galvanic reaction over time) and rolled or hopped eastward by about 200 m (Fig. 5). Oh dear!

Figure 5. A hydrophone lander after recovery. Notice all but 1 of the concrete anchor legs missing from the recovered lander and the amount of bio-fouling on the hydrophone (compared to Figure 2).







Thankfully, the hydrophone was well protected, and no air jetting was required. With OCA divers out of the water and clear, the Pacific Surveyor headed over to the floats and easily pulled the lander frame and hydrophone on board (Fig. 6). Yipee!

On to the next hydrophone station. This station, deployed ~ 800 m west of the south reef off of South Beach near the Yaquina Bay port entrance. It was deployed entirely subsurface and was outfitted with an acoustic release transponder that I could communicate with from the surface and command to release a pop-up messenger float and line for eventual recovery of the instrument frame. Once on station, communication with the release was established easily (a good start) and we began ranging and moving the OCA vessel Gracie Lynn in to a position within about 2 water depths of the unit (~40 m). I gave the command to the transponder and the submerged release confirmed it was free of its anchor and heading for the surface, but it never made it. Uh oh. Turns out this lander had also broke free of its anchored legs and rolled/ hopped 800 m eastward until it was pinned up against the boulder structure of the south reef. Amazingly, OCA divers Jenna and Doug located the messenger float ~ 5 m below the surface and the messenger line had been fouled by the rolling frame so it could not reach the surface. They dove down the messenger line and attached a new recovery line to the lander frame and the Pacific Surveyor hauled up the frame and hydrophone in-tact (Fig. 6). Double recovery success!

Figure 6. R/V Pacific Surveyor recovering hydrophone landers off Gull Rock and South Beach.

The hydrophone data from both systems looks outstanding and analysis is underway. This recovery effort took a huge amount of patience and the coordination of 3 busy groups (NOAA/OSU, OCA, Capt. Al). Thanks to these incredible collaborations and some heroic diving from Jim Burke and his OCA dive team, we now have a unique and unprecedented shallow water passive acoustic data set from the energetic waters off the Oregon coast.

So that’s some of the story from the 2016 and 2017 field season acoustic point of view. I’ll save the less exciting, but equally successful instrument recoveries from Port Orford for another time.

From the highs to the lows, that’s just how it blows!


By: Kelli Iddings, MSc Student, Duke University, Nicholas School of the Environment

The excitement is palpable as I wait in anticipation. But finally, “Blow!” I shout as I notice the lingering spray of seawater expelled from a gray whale as it surfaces to breathe. The team and I scurry about the field site taking our places and getting ready to track the whale’s movements. “Gray whale- Traveling- Group 1- Mark!” I exclaim mustering enough self-control to ignore the urge to drop everything and stand in complete awe of what in my mind is nothing short of a miracle. I’ve spotted a gray whale searching and foraging for food! As a student of the Master of Environmental Management program at Duke University, I am collaborating on a project in Port Orford, Oregon where my team and I are working to gain a better understanding of the interactions between the Pacific Coast Feeding Group (PCFG) gray whales and their prey. Check out this blog post written earlier by my teammate Florence to learn more about the methods of the project and what motivated us to take a closer look at the foraging behavior of this species.

Understanding the dynamics of gray whale foraging within ecosystems where they are feeding is essential to paint a more comprehensive picture of gray whale health and ecology—often with the intent to protect and conserve them. A lot of our recent effort has been focused on developing and testing methods that will allow us to answer the questions that we are asking. For example, what species of prey are the PCFG whales feeding on in Port Orford? Based on the results of a previous study (Newell and Cowles 2006) that was conducted in Depoe Bay, Oregon, and a lot of great knowledge from the local fisheries and the Port Orford community, we hypothesized that the whales were feeding on a small, shrimp-like crustacean in the order Mysida. Given the results of our videos, and the abundance of mysid, it looks like we are right (Fig. 1)!

Figure 1: Mysids, only 5-25mm in length, collected in Tichenor Cove using a downrigger to lower a weighted plankton net into the water column from our kayak.
Mysids are not typically the primary food source of gray whales. In their feeding grounds in the Bering and Chukchi Seas near Alaska, the whales feed on benthic amphipods on the ocean floor by sucking up sediment and water and pushing it through baleen plates that trap the food as the water and sediment is filtered out. However, gray whales demonstrate flexible feeding strategies and are considered opportunistic feeders, meaning they are not obligate feeders on one prey item like krill-dependent blue whales. In Oregon, mysid congregate in dense swarms by the billions, which we hypothesize, makes it energetically worthwhile for the massive 13-15m gray whales to hang around and feed! Figure 2 illustrates a mysid swarm of this kind in Tichenor Cove.

Figure 2: Image captured using a Hero 4 Black GoPro. Rocky Substrate is visible in lower portion of image and a clear swarm of mysid is aggregated around this area.

Once we know what the gray whales are eating, and why, we ask follow up questions like how is the distribution of mysid changing across space and time, if at all? Are there patterns? If so, are the patterns influencing the feeding behavior and movement of the whales? For the most part, we are having success characterizing the relative abundances of mysid. No conclusions can be made yet, but there are a few trends that we are noticing. For instance, it seems that the mysid are, as we hypothesized, very dense and abundant around the rocky shoreline where there are kelp beds. Could these characteristics be predictors of critical habitat that whales seek as foraging grounds? Is it the presence of kelp that mysid prefer? Or maybe it’s the rocky substrate itself? Distance to shore? Time and data analysis will tell. We have also noticed that mysid seem to prefer to hang out closer to the bottom of the water column. Last, but certainly not least, we are already noticing differences in the sizes and life stages of the mysid over the short span of one week at our research site! We are excited to explore these patterns further.

The biggest thing we’re learning out here, however, is the absolute necessity for patience, ingenuity, adaptability, and perseverance in science. You heard that right, as with most things, I am learning more from our failures, than I am from our successes.  For starters, understanding mysid abundance and distribution is great in and of itself, but we cannot draw any conclusions about how those factors are affecting whales if the whales don’t come! We were very fortunate to see whales while training on our instruments in Newport, north of our current study site. We saw whales foraging, whales searching, mother/calf pairs, and even whales breaching! Since we’ve been in Port Orford, we have seen only three whales, thrown in among the long hours of womanpower (#WomenInScience) we have been putting in! We are now learning the realities of ecological science that >gasp< fieldwork can be boring! Nevertheless, we trust that the whales will hear our calls (Yes, our literal whale calls. Like I said, it can get boring up on the cliff) and head on over to give the cliff team in Port Orford some great data—and excitement!

Then, there is the technology. Oh, the joys of technology. You see I’ve never considered myself a “techie.” Honestly, I didn’t even know what a hard drive was until some embarrassing time in the not-so-distant past. And now, here I am working on a project that is using novel, technology rich approaches to study what I am most passionate about. Oh, the irony. Alas, I have been putting on my big girl britches, saddling up, and taking the whale by the fluke. Days are spent syncing a GoPro, Time-Depth Recorder (TDR), GPS, associated software, and our trusty rugged laptop, all the while navigating across multiple hard drives, transferring and organizing massive amounts of data, reviewing and editing video footage, and trouble shooting all of it when something, inevitably, crashes, gets lost, or some other form of small tragedy associated with data management. Sounds fun, right? Nonetheless, within the chaos and despair, I realize that technology is my friend, not my foe. Technology allows us to collect more data than ever before, giving us the ability to see trends that we could not have seen otherwise, and expending much less physical effort doing so. Additionally, technology offers many alternatives to other invasive and potentially destructive methods of data collection. The truth is if you’re not technologically savvy in science these days, you can expect to fall behind. I am grateful to have an incredible team of support and such an exciting project to soften the blow. Below (Fig. 3) is a picture of myself embracing my new friend technology.

Figure 3: Retrieving the GoPro, and some tag-a-long kelp, from the water after a successful deployment in Tichenor Cove.

Last but not least, there are those moments that can best be explained by the Norwegian sentiment “Uff da!” I was introduced to the expression while dining at The Crazy Norwegian, known famously for having the best fish and chips along the entire west coast and located dangerously close to the field station. The expression dates back to the 19th century, and is used readily to concisely convey feelings of surprise, astonishment, exhaustion, and sometimes dismay. This past week, the team was witness to all of these feelings at once as our GoPro, TDR, and data fell swiftly to the bottom of the 42-degree waters of Tichenor cove after the line snapped during deployment. Uff da!!! With our dive contact out of town, red tape limiting our options, the holiday weekend looming ahead, and the dreadful thought of losing our equipment on a very tight budget, the team banded together to draft a plan. And what a beautiful plan it was! The communities of Port Orford, Oregon State University, and the University of Oregon’s Institute of Marine Biology came together in a successful attempt to retrieve the equipment. We offer much gratitude to Greg Ryder, our retrieval boat operator, OSU dive safety operator Kevin Buch, and our divers, Aaron Galloway and Taylor Eaton! After lying on the bottom of the cove for almost three days, the divers retrieved our equipment within 20 minutes of the dive – thanks to the quick and mindful action of our kayak team to mark a waypoint on the GPS at the time of the equipment loss. Please enjoy this shot (Fig. 4) of Aaron and Taylor surfacing with the gear as much as we do!

Figure 4: Aaron Galloway and Taylor Eaton surface with our lost piece of equipment after a successful dive retrieval mission.
Figure 4: Aaron Galloway and Taylor Eaton surface with our lost piece of equipment after a successful dive retrieval mission.

The moral of the story is that science isn’t easy, but it’s worth it. It takes hard work, long hours, frustration, commitment, collaboration, and preparedness. But moments come along when your team sits around a dining room table, exhausted from waking and paddling at 5 am that morning, and continues to drive forward. You creatively brainstorm, running on the fumes of the passion and love for the ocean and creatures within it that brought everyone together in the first place; each person growing in his or her own right. Questions are answered, conclusions are drawn, and you go to bed at the end of it all with a smile on your face, anxiously anticipating the little miracles that the next day’s light will bring.


Newell, C. and T.J. Cowles. (2006). Unusual gray whale Eschrichtius robustus feeding in the summer of 2005 off the central Oregon Coast. Geophysical Research Letters, 33:10.1029/2006GL027189