torresle, Author at Geospatial Ecology of Marine Megafauna Laboratory

Eavesdropping on blue whales in New Zealand

Kristin Brooke Hodge

Research Analyst, Bioacoustics Research Program, Cornell University

https://www.researchgate.net/profile/Kristin_Hodge

Over the past few weeks, we have surveyed the South Taranaki Bight, New Zealand, collecting biological and oceanographic data to learn more about the population of blue whales in this region. Our efforts have been successful: we have encountered multiple blue whales, and recorded information about their identification, behavior, and habitat. While our visual survey efforts have provided us with an invaluable dataset, our field season is shortly coming to an end. So how can we continue to learn more about the blue whale population, if we cannot collect visual survey data?

Solution: we will study the sounds they make.

Bioacoustics is a non-invasive method to study acoustically-active animal populations in terrestrial and marine habitats. Scientists can eavesdrop on animals by recording and analyzing their sounds, and in turn gain insights about their occurrence, behavior, and movement patterns. This is especially useful for studying elusive or rare species, such as the blue whale, that can be difficult to find in the field. Since blue whales produce high intensity, infrasonic calls and songs that can travel for many miles across ocean basins, we can capture information regarding their spatial and temporal occurrence, even if we cannot see them. (To listen to a blue whale call recorded off of Chile click here.)

We are using Marine Autonomous Recording Units (MARUs), developed by the Cornell Bioacoustics Research Program, to record blue whales (Fig. 1). The MARU is a digital audio recording system contained in a buoyant sphere, which is deployed on the bottom of the ocean using an anchor. Each MARU has a hydrophone that collects acoustic data, and these sounds are recorded and stored on electronic storage media inside the MARU. The MARUs are programmed to record continuous, low-frequency sounds for approximately six months, after which they pop up to the surface of the ocean, ready to be retrieved for data analysis and redeployed with fresh batteries and storage media.

Figure 1. Kristin Hodge about to deploy a Marine Autonomous Recording Unit (MARU) and anchors in the South Taranaki Bight of New Zealand.

Over the course of this field season, we strategically deployed five MARUs across the South Taranaki Bight (Fig. 2), and we will record acoustic data in these five sites over the next couple of years. This will allow us to understand patterns of occurrence at larger spatial and temporal scales than we can accomplish with visual survey alone. Our acoustic dataset will complement the biological and oceanographic data we collected on survey, providing a more complete picture of the blue whale population in the bight.

Figure 2. Approximate locations of Marine Autonomous Recording Unit (MARU) deployment sites across the South Taranaki Bight of New Zealand.

To see us deploy a MARU in New Zealand, check out this video:

Racing blues

By Dr. Leigh Torres, Assistant Professor, Oregon State University, Geospatial Ecology of Marine Megafauna Lab

A week ago we observed two racing blue whales.

Please read my blog about this amazing sighting that was recently posted on The National Geographic Explores webpage. You can also watch these videos:

Blues Clues

Although blue whales are big, the South Taranaki Bight is bigger. So finding them is not straight forward. In fact, with little prior research in this area, the main focus of our project is to gain a better understanding of blue whale distribution patterns in the region. So, while bouncing around on the sea, we are collecting habitat data that we relate to whale occurrence data to learn what makes preferred whale habitat.

We conduct CTD casts. CTD stands for Conductivity, Temperature and Depth. This is an instrument we lower down to the bottom of the ocean on a line and along the w ay it records temperature and salinity (conductivity) data at all depths. This data describes the water structure at that location, such as the depth of the thermocline. The ocean is often layered with warm, low-salt water on top, and cooler and salty water at the bottom. This thermocline can act as a boundary above which prey aggregate.

Todd and Andrew deploy the CTD off the R/V Ikatere. (Photo by Callum Lilley)

We also have a transducer on board that we use to record the presence of biological material in the ocean, like krill (blue whale prey). This transducer emits pings of sound through the water column and the echoes bounce back, either off the seafloor, krill or fish. This glorified echosounder records where blue whale prey is, and is not.

Example display image from our echosounder (EK60) showing patches of prey (likely krill) in the upper surface layer.

Additionally, the research vessel is always recording surface temperature (SST). I monitor this SST readout somewhat obsessively while at-sea as well as study the latest SST satellite images. Using these two bits of data as my “blues clues”, we search for blue whales.

After a bumpy ride across the Cook Strait we had a good spell of weather last week. We covered a lot of ground, deploying our 5 hydrophones across the Bight and keeping our eyes peeled for blows. Our first day out we found three whales. Fantastic sightings. But, as we continued to survey through warm, low productivity water we found no signs of blue whales. The third day out was a beauty – the type of day I wish for: low swell and low winds – perfect for whale finding. We covered 220 nautical miles this day (deploying 2 hydrophones) and we searched and searched. But no whales. I could see from the SST satellite image that the whole Bight was really warm: about 20 ⁰C. I could also see a strip of cold water down south, toward Farewell Spit. I said “Let’s go there”.

Sea surface temperature (SST) satellite image of the South Taranaki Bight region in New Zealand that shows mostly warm water with a plume of colder water down south.

After twelve and a half hours of survey effort through clear, blue, warm water, we finally saw the water temperature drop (to about 18 ⁰C) and the water color turn green. We started to see gannets, petrels, shearwaters, and common dolphins feeding. Then I heard the magic words come from Todd’s mouth: “Blow!” So began our sunset sighting. From 7:30 to 10 pm we worked with four blue whales capturing photographs and biopsy samples, and echosounder prey data.

Diving blue whale in the South Taranaki Bight, NZ (photo by Leigh Torres)

This is an example of a species-habitat relationship that marine ecologists like me seek to document. We observe and record patterns like this so that we can better understand and predict the distribution of blue whales. Such information is critical for environmental managers to have in order to effectively regulate where and when human activities that may impact blue whales can occur. Over the next two weeks we will continue to document blue whale habitat in the South Taranaki Bight region of New Zealand.

Blown out.

By Dr. Leigh Torres, Assistant Professor, Oregon State University, Marine Mammal Institute, Geospatial Ecology of Marine Megafauna Lab

Hurry up and wait. Can’t control the weather. All set and nowhere to go.

However you want to say it, despite our best efforts to be ready to sail today, the weather has not agreed with our best-laid plans. It’s blowing 20-30 knots in the South Taranaki Bight, which makes it very difficult to spot a whale from our small (but sturdy) research vessel (NIWA’s R/V Ikatere), and practically impossible to take good photos of the whales or to deploy our hydrophones. So, we wait.

Over the last few days we have been busy tracking down gear, assembling the hydrophones, discussing project logistics, preparing equipment (Fig. 1), provisioning the vessel, getting the crew in place, and practicing vessel operations. We have flown to the other side of the world. We have prepared. We are ready. And we wait. Such is field work. I know this. I’ve been through this many times. But it is always hard to take when you feel the clock ticking on your timeline, the funds flowing from your budget, and your people waiting for action. Fortunately, I have built in contingency time so we will still accomplish our goals. We just have to wait a bit longer. As the Kiwis say, ‘Bugger!’

kristin and hydrophones small — Figure 1. Kristin Brooke Hodge of The Bioacoustics Research Program at Cornell University performs a global sound check on the hydrophones (loud bang of hammer to pipe) so that times can all be synced and any clock drift accounted for.

Below is a wind and rain forecast for New Zealand (provide by the MetService). The box in red is our study region of the South Taranaki Bight. We are currently in Wellington where the green star is, but we want to be in Pohara where the yellow star is – this will be our base during the field project, if we can just get there.

Wind strength and direction in these types of maps is depicted by the wind indicator lines: the wind is coming from the tail toward the flag end of the symbol, and the strength is symbolized by the number and size of the barbs on the flag end.

Notice how inside the red box there are lots of barbs on the indicator lines (most saying about 20 knots), but just to the west and north there are few barbs – about 5 to 10 knots. These are great survey conditions, but not where we want to be! A bit heartbreaking. But that’s how it goes, and I know we will get our weather window soon. Until then, we sit tight and watch the wind blow through the pohutukawas and cabbage trees in beautiful Wellington.

“This is what I would do if I weren’t afraid” – New Zealand blue whale field season 2016

By Dr. Leigh Torres, Assistant Professor, Oregon State University, Geospatial Ecology of Marine Megafauna Lab

Two years ago I documented a blue whale foraging ground in an area of New Zealand called the South Taranaki Bight (STB) – the country’s most industrially active marine area with intense oil and gas exploration and extraction since the 1970’s, elevated vessel traffic, and potential seabed mining (Figure 1). Over just five days of survey effort we observed 50 blue whales and documented foraging behavior. But we still know next to nothing about where and when blue whales are in the STB, how many whales use this area, how important this area is as a feeding area, or to what population the whales belong. Without answers to these questions effective management of human activities in the region to protect the whales and their habitat is unfeasible.

I am now heading back to New Zealand to collect the data needed to answer these questions that will enable successful management. That’s my goal.

Figure 1. Illustration of a space-use conflict between industry activity and blue whales in the South Taranaki Bight, which lies between the north and south islands of New Zealand. Blue whale sightings and strandings recorded between 1970 and 2012.

Such research costs money. In collaboration with the Bioacoustic Research Program at Cornell University (birds.cornell.edu/brp), we are deploying five hydrophones to listen for blue whales across the region for 2 years. We will conduct vessel surveys for 1 month in each year to find whales and collect data on their habitat, behavior, and individual occurrence patterns. As far as field research projects go, this work is not very expensive, but we still need to pay for vessel time, equipment, and personnel time to collect and analyze the data. This is an ugly truth of scientific research – it costs money and there is not a lot out there.

For two years I’ve had my fund raising hat on (Not my favorite hat. I much prefer my research hat). I believe that industry groups active in the STB should take an active role in supporting the necessary research. They exploit the natural resources in the region and should therefore take responsibility for ensuring the ecosystem’s sustainability and health. Right? They did not agree.

I emphasized to these groups that by supporting the project they would demonstrate their environmental responsibility and ultimately be engaged in discussions of management options based on project findings. Despite hundreds of emails, phone calls and discussions, all the oil and gas companies, the seabed mining group, and the maritime traffic organization declined to fund the project, claiming lack of funds or lack of relevance to their interests. Meanwhile, other groups who prioritize conservation management are supporting the project. I am grateful to The Aotearoa Foundation, The National Geographic Society Waitt Foundation, The New Zealand Department of Conservation, Greenpeace New Zealand, OceanCare, Kiwis Against Seabed Mining, and an anonymous donor.

Lately I have been reading Sheryl Sandberg’s poignant book, Lean In, which I feel is a call to women to take responsibility for our equality and leadership. Those familiar with this book will recognize the opening of my blog title from her valid push for women to take more risks and push ourselves beyond our comfort zones. In many ways I feel I am doing this now. It would be much easier for me to withdraw from this project, say I tried, and let things carry on until someone else takes the challenge. Funding is short, last minute contract issues abound, equipment logistics are running late, I fear political pushback, and I have a sore throat. But it’s time for this project to happen. It’s time to recognize biodiversity’s innate right to healthy habitat. It’s time for industry groups to acknowledge their potential impacts on blue whales through elevated ocean noise, vessel strikes, and habitat degradation and displacement. It’s time for management to have the tools to act.

Figure 2. A blue whale surfaces in front of an oil rig in the South Taranaki Bight, New Zealand. Photo by Deanna Elvines.

I remain hopeful that industry groups will engage in this research effort. Through diplomacy, transparency and robust science I want to bring together industry, NGOs, and management groups to develop effective conservation strategies to protect blue whales and their habitat in the STB. Collaboratively we can balance industry activity and biodiversity protection.

Since reading Lean In, I’ve been wondering if the conservation movement suffers because of women’s reluctance to challenge, take risks, and ‘sit at the table’ as Sandberg says. The conservation field is heavily dominated by women. For progress to happen we must be willing to force issues, be perceived as aggressive, and not be nice all the time. Just like men are expected to be.

Over the next four weeks colleagues and I will conduct research in the STB on blue whales. Stay tuned to this blog for updates.

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