Finding the edge: Preliminary insights into blue whale habitat selection in New Zealand

By Dawn Barlow, MSc student, OSU Department of Fisheries and Wildlife, Geospatial Ecology of Marine Megafauna Lab

I was fortunate enough to spend the Austral summer in the field, and so while the winter rain poured down on Oregon I found myself on the water with the sun and wind on my face, looking for blue whales in New Zealand. This spring I switched gears and spent time taking courses to build my analytical toolbox. In a course on technical writing and communication, I was challenged to present my research using only pictures and words with no written text, and to succinctly summarize the importance of my research in an introduction to a technical paper. I attended weekly seminars to learn about the diverse array of marine science being conducted at Oregon State University and beyond. I also took a course entitled “Advanced Spatial Statistics and Geographic Information Science”. In this skill-building course, we were given the opportunity to work with our own data. Even though my primary objective was to expand the tools in my toolbox, I was excited to explore preliminary results and possible insight into blue whale habitat selection in my study area, the South Taranaki Bight region (STB) of New Zealand (Figure 1).

Figure 1. A map of New Zealand, with the South Taranaki Bight (STB) region delineated by the black box. Farewell Spit is denoted by a star, and Kahurangi point is denoted by an X.

Despite the recent documentation of a foraging ground in the STB, blue whale distribution remains poorly understood in New Zealand. The STB is New Zealand’s most industrially active marine region, and the site of active oil and gas extraction and exploration, busy shipping traffic, and proposed seabed mining. This potential space-use conflict between endangered whales and industry warrants further investigation into the spatial and temporal extent of blue whale habitat in the region. One of my research objectives is to investigate the relationship between blue whales and their environment, and ultimately to build a model that can predict blue whale presence based on physical and biological oceanographic features. For this spring term, the question I asked was:

Is the number of blue whales present in an area correlated with remotely-sensed sea surface temperature and chlorophyll-a concentration?

For the purposes of this exploration, I used data from our 2017 survey of the STB. This meant importing our ship’s track and our blue whale sighting locations into ArcGIS, so that the data went from looking like this:

… to this:

The next step was to get remote-sensed images for sea surface temperature (SST) and chlorophyll-a (chl-a) concentration. I downloaded monthly averages from the NASA Moderate Resolution Imaging Spectrometer (MODIS aqua) website for the month of February 2017 at 4 km2 resolution, when our survey took place. Now, my images looked something more like this:

But, I can’t say anything reliable about the relationships between blue whales and their environment in the places we did not survey.  So next I extracted just the portions of my remote-sensed images where we conducted survey effort. Now my maps looked more like this one:

The above map shows SST along our ship’s track, and the locations where we found whales. Just looking at this plot, it seems like the blue whales were observed in both warmer and colder waters, not exclusively in one or the other. There is a productive plume of cold, upwelled water in the STB that is generated off of Kahurangi point and curves around Farewell Spit and into the bight (Figure 1). Most of the whales we saw appear to be near that plume. But how can I find the edges of this upwelled plume? Well, I can look at the amount of change in SST and chl-a across a spatial area. The places where warm and cold water meet can be found by assessing the amount of variability—the standard deviation—in the temperature of the water. In ArcGIS, I calculated the deviation in SST and chl-a concentration across the surrounding 20 km2 for each 4 km2 cell.

Now, how do I tie all of these qualitative visual assessments together to produce a quantitative result? With a statistical model! This next step gives me the opportunity to flex some other analytical muscles, and practice using another computational tool: R. I used a generalized additive model (GAM) to investigate the relationships between the number of blue whales observed in each 4 km2 cell our ship surveyed and the remote-sensed variables. The model can be written like this:

Number of blue whales ~ SST + chl-a + sd(SST) + sd(chl-a)

In other words, are SST, chl-a concentration, deviation in SST, and deviation in chl-a concentration correlated with the number of blue whales observed within each 4 km2 cell on my map?

This model found that the most important predictor was the deviation in SST. In other words, these New Zealand blue whales may be seeking the edges of the upwelling plume, honing in on places where warm and cold water meet. Thinking back on the time I spent in the field, we often saw feeding blue whales diving along lines of mixing water masses where the water column was filled with aggregations of krill, blue whale prey. Studies of marine mammals in other parts of the world have also found that eddies and oceanic fronts—edges between warm and cold water masses—are important habitat features where productivity is increased due to mixing of water masses. The same may be true for these New Zealand blue whales.

These preliminary findings emphasize the benefit of having both presence and absence data. The analysis I have presented here is certainly strengthened by having environmental measurements for locations where we did not see whales. This is comforting, considering the feelings of impatience generated by days on the water spent like this with no whales to be seen:

Moving forward, I will include the blue whale sighting data from our 2014 and 2016 surveys as well. As I think about what would make this model more robust, it would be interesting to see if the patterns become clearer when I incorporate behavior into the model—if I look at whales that are foraging and traveling separately, are the results different? I hope to explore the importance of the upwelling plume in more detail—does the distance from the edge of the upwelling plume matter? And finally, I want to adjust the spatial and temporal scales of my analysis—do patterns shift or become clearer if I don’t use monthly averages, or if I change the grid cell sizes on my maps?

I feel more confident in my growing toolbox, and look forward to improving this model in the coming months! Stay tuned.

Keeping up with blue whales in a dynamic environment

By Dawn Barlow, MSc student, Department of Fisheries and Wildlife, Geospatial Ecology of Marine Megafauna Lab

“The marine environment is patchy and dynamic”. This is a phrase I have heard, read, and written repeatedly in my studies of marine ecology, and it has become increasingly tangible during the past several weeks of fieldwork. The presence of the blue whales we’ve come here to study is the culmination of a chain of events that begins with the wind. As we huddle up at anchor or in port while the winds blow through the South Taranaki Bight, the water gets mixed and our satellite images show blooms of little phytoplankton lifeforms. These little phytoplankton provide food for the krill, the main prey item of far larger animals—blue whales. And in this dynamic environment, nothing stays the same for long. As the winds change, aggregations of phytoplankton, krill and whales shift.

When you spend hours and hours scanning for blue whales, you also grow intimately familiar with everything that could possibly look like a blue whale but is not. Teasers include whitecaps, little clouds on the horizon, albatrosses changing flight direction, streaks on your sunglasses, and floating logs. Let me tell you, if we came here to study logs we would have quite the comprehensive dataset! We have had a few days of long hours with good weather conditions and no whales, and it is difficult not to be frustrated at those times—we came here to find whales. But the whale-less days prompt musings of what drives blue whale distribution, foraging energetics, and dreams of elaborate future studies and analyses, along with a whole lot of wishing for whales. Because, let’s admit it, presence data is just more fun to collect.

The view from the flying bridge of R/V Star Keys of Mt. Taranaki and a calm sea with no whales in sight. Photo by D. Barlow.

But we’ve also had survey days filled with so many whales that I can barely keep track of all of them. When as soon as we begin to head in the direction of one whale, we spot three more in the immediate area. Excited shouts of “UP!! Two o’clock at 300 meters!” “What are your frame numbers for your right side photos?” “Let’s come 25 degrees to port” “UUUPPP!! Off the bow!” “POOOOOOP! Grab the net!!” fill the flying bridge as the team springs into action. We’ve now spotted 40 blue whales, collected 8 biopsy samples, 8 fecal samples, flown the drone over 9 whales, and taken 4,651 photographs. And we still have more survey days ahead of us!

A blue whale surfaces just off the bow of R/V Star Keys. Photo by D. Barlow.

In Leigh’s most recent blog post she described our multi-faceted fieldwork here in the South Taranaki Bight. Having a small inflatable skiff has allowed for close approaches to the whales for photo-identification and biopsy sample collection while our larger research vessel collects important oceanographic data concurrently. I’ve been reading numerous papers linking the distribution of large marine animals such as whales with oceanographic features such as fronts, temperature, and primary productivity. In one particular sighting, the R/V Star Keys idled in the midst of a group of ~13 blue whales, and I could see foamy lines on the surface where water masses met and mixed. The whales were diving deep—flukes the size of a mid-sized car gracefully lifting out of the water. I looked at the screen of the echosounder as it pinged away, bouncing off a dense layer of krill (blue whale prey) just above the seafloor at around 100 meters water depth.  As I took in the scene from the flying bridge, I could picture these big whales diving down to that krill layer and lunge feeding, gorging themselves in these cool, productive waters. It is all mostly speculative at this point and lots of data analysis time remains, but ideas are cultivated and validated when you experience your data firsthand.

A blue whale shows its fluke as it dives deep in an area with abundant krill deep in the water column. Photo by L. Torres.

The days filled with whales make the days without whales worthwhile and valuable. To emphasize the dynamic nature of the environment we study, when we returned to an area in which we had seen heaps of whales just 12 hours before, we only found glassy smooth water and no whales whatsoever. Changing our trajectory, we came across nothing for the first half of the day and then one pair of whales after another. Some traveling, some feeding, and two mother-calf pairs.

The dynamic nature of the marine environment and the high mobility of our study species is what makes this work challenging, frustrating, exciting, and fascinating. Now we’re ready to take advantage of our next weather window to continue our survey effort and build our ever-growing dataset. I relish the wind-swept, sunburnt days of scanning and musing, and I also look forward to settling down with all of these data to try my best to compile all of the pieces of this blue whale puzzle. And I know that when I find myself behind a computer screen processing and analyzing photos, survey effort, drone footage, and oceanographic data I will be imagining the blue waters of the South Taranaki Bight, the excitement of seeing the water glow brilliantly just before a whale surfaces off our bow, and whale-filled survey days that end only when the sun sets over the water.

A big moon rises to the east and a bright oil rig on the horizon at the end of a long and fruitful survey day. Photo by L. Torres.
And to the west of the moon and the rig, the sun sets over the South Taranaki Bight. Photo by L. Torres.

 

R/V Oceanus Day One: Hungry Hungry Humpbacks

By Florence Sullivan and Amanda Holdman

The GEMM lab is adventuring out into the wild blue yonder of open ocean sampling and educational outreach! Leigh is the chief scientist onboard the R/V Oceanus for the next two days as we sail through Oregon waters in search of marine megafauna. Also onboard are four local teachers and five high school students who are learning the tricks of the trade. Amanda and I are here to help teach basic oceanography and distance sampling techniques to our enthusiastic students.

Science Party musters in the dry lab for safety debrief. photo credit: Florence Sullivan
Science Party musters in the dry lab for safety debrief. photo credit: Florence Sullivan

We started the morning with safety briefings, and headed out through the Newport breakwater, direction: Stonewall Bank.  Stonewall is a local bathymetric feature where upwelling often occurs, leading to a productive ecosystem for both predators and prey. Even though our main sampling effort will be offshore this trip, we didn’t even make out of the harbor before recording our first gray whale and California sea lion sightings.

California Sea Lions on the Newport buoy. Taken under NMFS permit 16111 John Calambokidis
California Sea Lions on the Newport buoy. Taken under NMFS permit 16111 John Calambokidis

Our students (and their teachers) are eager and quick to catch on as we teach them new methodologies. Amanda and I had prepared presentations about basic oceanographic and distance sampling methods, but really the best way to learn is to jump in and go. We’ve set up a rotation schedule, and everyone is taking turns scanning the ocean for critters, deploying and recovering the CTD, logging data, and catching plankton.

a small pod of Orca. Photo credit: Florence Sullivan. Taken under NMFS permit 16111 John Calambokidis
A small pod of Orca. Photo credit: Florence Sullivan. Taken under NMFS permit 16111 John Calambokidis

So far, we have spotted gray whales, sea lions, a pod of (lightning speed) killer whales, lots of seagulls, northern fulmars, sooty shearwaters, storm petrels, and cormorants, but today’s highlight has to the last sighting of ~42 humpback whales. We found them at the Northern edge of Heceta Bank – a large rocky reef which provides structural habitat for a wide variety of marine species. As we approached the area, we spotted one whale, and then another. At first, our spotters had no trouble inputting the data, getting photo-ID shots, and distinguishing one whale from the next, but as we continued, we were soon overwhelmed. With whale blows surrounding us on all sides, it was hard to know where to look first – here a surface lunge, there, a breach, a spout, a fluke, a flipper slap! The surface activity was so dense and enthralling, it took a few moments before realizing there were some sea lions in the feeding frenzy too!

Five humpback whales surface at once. photo credit: Leigh Torres. Taken under NMFS permit 16111 John Calambokidis
Five humpback whales surface at once. photo credit: Leigh Torres. Taken under NMFS permit 16111 John Calambokidis

We observed the group, and tried to document as many individuals as possible as the sunset faded into night. When poor visibility put a stop to the visuals, we hurried to do a plankton tow and CTD cast to find some environmental insights for such a gathering. The CTD revealed a stratified water column, with two distinct layers, and the plankton tow brought up lots of diatoms and krill. As one of the goals of this cruise is to explore how marine mammals vary with ocean gradients, this is a pretty cool way to start.

A humpback whale lunge feeds. Photo credit: Leigh Torres. Taken under NMFS permit 16111 John Calambokidis
A humpback whale lunge feeds. Photo credit: Leigh Torres. Taken under NMFS permit 16111 John Calambokidis

A long day observing has left us all exhausted, but not too tired to share our excitement. Stay tuned for more updates from the briny blue!

Follow this link for real time view of our beautiful ship! : http://webcam.oregonstate.edu/oceanus

Humpback flukes for photo ID. photo credit: Leigh Torres. Taken under NMFS permit 16111 John Calambokidis
Humpback flukes for photo ID. photo credit: Leigh Torres. Taken under NMFS permit 16111 John Calambokidis

An update on Oregon’s sound sensitive marine mammal, the harbor porpoise.

By Amanda Holdman, M.S. Student

Marine renewable energy is developing at great speeds all around the world. In 2013, the Northwest Marine Renewable Energy Center (NMREC) chose Newport, Oregon as the future site of first utility-scale, grid-connected wave energy test site in the United States – The Pacific Marine Energy Center (PMEC). The development of marine energy holds great potential to help meet our energy needs – it is renewable, and it is predicted that marine energy sources could fulfill nearly one-third of the United States energy demands.

Wave energy construction in Newport could begin as early as 2017. Therefore, it is important to fully understand the potential risks and benefits of wave energy as the industry moves forward. Currently, there is limited information on wave energy devices and the potential ecological impacts that they may have on marine mammals and their habitats. In order to assess the effects of wave energy, pertinent information needs to be collected prior to the installation of the devices.

This is where I contribute to the wave energy industry in Oregon.

Harbor porpoise are a focal species when it comes to renewable energy management; they are sensitive to a range of anthropogenic sounds at very low levels of exposure and may show behavioral responses before other marine mammals, making them a great indicator species for potential problems with wave energy. Little is known about harbor porpoise in Oregon, necessitating the need to look at the fine scale habitat use patterns of harbor porpoise within the proposed wave energy sites.

I used two methods to study harbor porpoise presence and activity in coastal waters: visual boat surveys, and passive acoustic monitoring. Visual surveys have a high spatial resolution and a low temporal resolution, meaning you can conduct visual boat surveys over a wide area, but only during daylight hours. Whereas acoustic surveys have opposite characteristics; you can conduct surveys during all hours of the day, however, the range of the acoustic device is only a few hundred meters. Therefore, these methods work well together to gain complimentary information about harbor porpoise. These methods are crucial for collecting baseline data on harbor porpoise distribution, and providing valuable information for understanding, managing, and mitigating potential impacts.

Bi-monthly standard visual line-transect surveys were conducted for two full years (October 2013-2015), while acoustic devices were deployed May – October 2014. Field work ended last October, and since then, data analysis efforts have uncovered  seasonal, diel, and tidal patterns in harbor porpoise occurrence and activity.

Harbor porpoises in Oregon are thought to be seasonally migratory. With the onset of spring, coinciding with the start of the upwelling season, porpoise are thought to move inshore and abundance increases into the summer. Most births also occur during the late spring and summer. With the return of winter, porpoise are thought to leave the coastal waters and head out to the deeper waters (Dohl 1983, Barlow 1988, Green et al. 1992).

Results from my data support this seasonal trend. Both visual survey and acoustic recording data document the general pattern of peak porpoise presence occurring in the summer months of June and July, with a gradual decline of detections into the fall (Fig. 1 & 2).

1

Figure 1: Overall, from our acoustic surveys we see a large increase from May to June, suggesting the arrival of harbor porpoise to coastal waters. From July, we see a slow decline into the fall months, suggestive of harbor porpoise moving offshore.

2

Figure 2: Our data from visual surveys mimic those of our acoustic surveys. We see a large increase of porpoises from May to June and then a decline into the fall. We had very low survey effort in July, due to rough seas.  If we were able to survey more, it is likely we would have seen more harbor porpoise during this time.

Using acoustic recorders, we are able to get data on harbor porpoise occurrence throughout all hours of the day, regardless of weather conditions. We deployed hydrophones in two locations – one in a near-shore REEF habitat located 4 km from shore, and the second in the middle of the South Energy Testing Site (SETS) 12 km off-shore. These two sites differ in depth and habitat type. The REEF habitat is 30 m deep and has a rocky bottom as a habitat type, while SETS is 60 m deep and has a sandy bottom. When we compare the two sites (Figure 3), we can see that harbor porpoise have a preference for the REEF site.

Additionally, we are also able to get some indices of behavior from acoustic recordings. Equivalent to sonar or radar, marine mammals use echolocation (high frequency sounds) to communicate and navigate. Marine mammals, specifically odonotocetes, also use echolocation to locate prey at depth when there is very little or no light. Porpoises use a series of clicks during their dives, and as the porpoise approach their prey, the clicks become closer and closer together so they sound like a continuous buzz. When studying echolocation patterns in odontocetes we typically look at the inter-click-intervals (ICIs) or the time between clicks. When ICIs are very close together (less than 10 ms apart) it is considered a foraging behavior or a buzz. Anything greater than 10 ms is classified as other (or clicks in this figure).

Click_Buzz_bargraph.

Figure 3: We see harbor porpoise clicks were detected about 27% of the time at the REEF, but only 18% at SETS. Potential feeding was also higher at the REEF site (14%) compared to (4%) at SETS.

Not only did we find patterns in foraging behavior between the two sites, we also found foraging patterns across diel cycles and tidal cycles:

  1. We found a tendency for harbor porpoise to forage more at night (Figure 4).
  2. The diel pattern of harbor porpoise foraging is stronger at the SETS than the REEF site (Figure 4). This result may be due to the prey at the SETS (sandy bottom) exhibiting vertical migration with the day and night cycles since prey there do not have alternative cover, as they would in the rocky reef habitat.
  3. At the reef site, we see a relationship between increased foraging behavior and low tide (Figure 5).

ratio

Figure 4: When analyzing data for trends in foraging behavior across different sites and diel cycles, we use a ratio of buzzes to clicks, so that we incorporate both echolocation behaviors in one value. This figure shows us that the ratio of buzzes to clicks is pretty similar at the REEF site across diel periods, but there is more variation at the SETS site, with more detections at night and during sunrise.

blog_5

Figure 5: Due to the circular nature of tides rotating between high tide and low tide, circular histograms help to observe patterns. In this figure, we see a large preference for harbor porpoise to feed during low tide. We are unclear why harbor porpoise may prefer low tide, but the relationship may be due to minimal current movement that could enhance feeding opportunities for porpoises.

Overall, the combination of visual surveys and passive acoustic monitoring has provided high quality baseline data on harbor porpoise occurrence patterns. It is results like these that can help with decisions regarding wave energy siting, operation and permitting off of the Oregon Coast.

REFERENCES

Barlow, J. 1987. Abundance estimation for harbor porpoise (Phocoena phocoena) based on ship surveys along the coasts of California, Oregon and Washington. SWFC Administrative Report LJ-87-05. Southwest Fishery Center, La Jolla, CA. 36pp.

Dohl, T.P., Guess, R.C., Dunman, M.L. and Helm, R.C. 1983, Cetaceans of central and northern California, 1980-83: status, abundance, and distribution. Final Report to the Minerals Management Service, Contract 14-12-0001-29090. 285pp.

Green, G.A., Brueggeman, J. J., Grotefendt, R.A., Bowlby, C.E., Bonnel, M. L. and Balcomb, K.C. 1992. Cetacean distribution and abundance off Oregon and Washington, 1989-1990. Chapter 1 In Oregon and Washington Marine Mammal and Seabird Surveys. Ed. By J. J. Brueggeman. Minerals Management Service Contract Report 14-12-0001-30426.

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.
Todd and Andrew deploy the CTD off the R/V Ikatere. (Photo by Callum Lilley)
CTD cast
Example data retrieved from a CTD cast showing how temperature (green line) decreases and salinity (red line) increases as it descends through the water column (depth on y-axis).

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.
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.
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)
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.

New Zealand’s mega-fauna come to Newport, Oregon.

By Olivia Hamilton, PhD Candidate, University of Auckland, New Zealand.

The week leading up to my departure from New Zealand was an emotional rollercoaster. Excited, nervous, eager, reluctant… I did not feel like the fearless adventurer that I thought I was. D-day arrived and I said my final goodbyes to my boyfriend and mother at the departure gate. Off I went on my three-month research stint at the Hatfield Marine Science Center.

Some thirty hours later I touched down in Portland. I collected my bags and headed towards the public transport area at the airport. A young man greeted me, “Would you like to catch a taxi or a shuttle, ma’am?” “A taxi please! I have no idea where I am”, I responded. He nodded and smiled. I could see the confusion all over his face… My thick kiwi accent was going to make for some challenging conversations.

After a few days in Portland acclimatizing to the different way of life in Oregon, it was time to push on to Newport. I hit a stroke of luck and was able take the scenic route with one of the girls in the GEMM lab, Rachael Orben. With only one wrong turn we made it to the Oregon coast. I was instantly hit with a sense of familiarity. The rugged coastline and temperate coastal forest resembled that of the west coast of New Zealand. However, America was not shy in reminding me of where I was with its big cars, drive-through everything, and RVs larger than some small kiwi houses.

The Oregon Coast. Photo by Olivia Hamilton.
The Oregon Coast. Photo by Olivia Hamilton.

We arrived at Hatfield Marine Science Center: the place I was to call home for the next quarter of a year.

So, what am I doing here?

In short, I have come to do computer work on the other side of the world.

Dr. Leigh Torres is on my PhD committee and I am lucky enough to have been given the opportunity to come to Newport and analyze my data under her guidance.

My PhD has a broad interest in the spatial ecology of mega-fauna in the Hauraki Gulf, New Zealand. For my study, megafauna includes whales, dolphins, sharks, rays, and seabirds. The Hauraki Gulf is adjacent to Auckland, New Zealand’s most populated city and home to one of our largest commercial ports. The Hauraki Gulf is a highly productive area, providing an ideal habitat for a number of fish species, thus supporting a number of top marine predators. As with many coastal areas, anthropogenic activities have degraded the health of the Gulf’s ecosystem. Commercial and recreational fishing, run-off from surrounding urban and rural land, boat traffic, pollution, dredging, and aquaculture are some of the main activities that threaten the Gulf and the species that inhabit it. For instance, the Nationally Endangered Bryde’s whale is a year-round resident in the Hauraki Gulf and these whales spend much of their time close to the surface, making them highly vulnerable to injury or death from ship-strikes. In spite of these threats, the Gulf supports a number of top marine predators.  Therefore it is important that we uncover how these top predators are using the Gulf, in both space and time, to identify ecologically important parts of their habitat. Moreover, this study presents a unique opportunity to look at the relationships between top marine predators and their prey inhabiting a common area.

The Hauraki Gulf, New Zealand. The purple lines represent the track lines that aerial surveys were conducted along.

 

Common dolphins in the Hauraki Gulf. Photo by Olivia Hamilton
Common dolphins in the Hauraki Gulf. Photo by Olivia Hamilton

 

A Bryde’s whale, common dolphins, and some opportunistic seabirds foraging in the Hauraki Gulf. Photo by Isabella Tortora Brayda di Belvedere.
A Bryde’s whale, common dolphins, and some opportunistic seabirds foraging in the Hauraki Gulf. Photo by Isabella Tortora Brayda di Belvedere.

 

Australisian Gannets and shearwaters foraging on a bait ball in the Hauraki Gulf. Photo by Olivia Hamilton.
Australisian Gannets and shearwaters foraging on a bait ball in the Hauraki Gulf. Photo by Olivia Hamilton.

To collect the data needed to understand the spatial ecology of these megafauna, we conducted 22 aerial surveys over a year-long period along pre-determined track lines within the Hauraki Gulf. On each flight we had four observers that collected sightings data for cetaceans, sharks, predatory fish, prey balls, plankton, and other rare species such as manta ray. An experienced seabird observer joined us approximately once a month to identify seabirds. We collected environmental data for each sighting including Beaufort Sea State, glare, and water color.

The summary of our sightings show that common dolphins were indeed common, being the most frequent species we observed. The most frequently encountered sharks were bronze whalers, smooth hammerhead sharks, and blue sharks. Sightings of Bryde’s whales were lower than we had hoped, most likely an artifact of our survey design relative to their distribution patterns. In addition, we counted a cumulative total of 11,172 individual seabirds representing 16 species.

Summary of sightings of megafauna in the Hauraki Gulf.

Summary of sightings of megafauna in the Hauraki Gulf.My goal while here at OSU is to develop habitat models for the megafauna species to compare the drivers of their distribution patterns. But, at the moment I am in the less glamorous, but highly important, data processing and decision-making stage. I am grappling with questions like: What environmental variables affected our ability to detect which species on surveys? How do we account for this? Can we clump species that are functionally similar to increase our sample size? These questions are important to address in order to produce reliable results that reflect the megafauna species true distribution patterns.

Once these questions are addressed, we can get on to the fun stuff – the habitat modeling and interpretation of the results. I will hopefully be able to start addressing these questions soon: What environmental and biological variables are important predictors of habitat use for different taxa? Are there interactions (attraction or repulsion) between these top predators? What is driving these patterns? Predator avoidance? Competition? So many questions to ask! I am looking forward to answering these questions and reporting back.

From Oregon to New Caledonia: Crossing latitudes

**GUEST POST** written by Solène Derville from the Institute of Research for Development, Nouméa, New Caledonia. Entropie Lab

Last term I posted about the analysis of Maui dolphin habitat selection I have undergone under Dr Leigh Torres’ supervision at OSU. The results of this work are now compiled in a manuscript which I hope to submit for publication very soon.

Since I last posted on this blog, many things have changed for me: I went back to France at the end of May (with a heavy heart from leaving Newport and my dear lab mates) and I have graduated from the Ecole Normale Supérieure of Lyon and successfully completed my Biology Master’s degree. In September, I will start a PhD on the spatial ecology of Humpback Whales in New Caledonia. I will work at the French ‘Institut de Recherche pour le Développement’ in Nouméa, New Caledonia, under the co-supervision of Dr Claude Payri, Dr Claire Garrigue, Dr Corina Iovan (IRD) and Dr Leigh Torres (GEMM Lab, OSU).

Before telling you a bit more about my project and this summer field season, I would like to introduce the beautiful place where I will be spending the next 3 years. New Caledonia is an archipelago located in the southwest Pacific Ocean, east of Australia. This special overseas French collectivity includes a main island (Grande Terre) and several other islands such as the Loyalty Islands. New Caledonia’s lagoon is the largest in the world and was added to the list of the UNESCO world heritage sites in 2008, because of its exceptional biodiversity including many emblematic species such as humpback whales, dugongs, marine turtles, manta rays…and many others.

).new+caledonia+mapNew Caledonia location in South Pacific Ocean (map: http://springtimeofnations.blogspot.jp

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Map of the New Caledonian Archipelago (map: http://crosbiew.wordpress.com).

Moreover, the ‘Natural Park of the Coral Sea’ was established very recently by the New Caledonian to protect this biodiversity hotspot. This monumental marine park spans 1.3 million square kilometres and is, to date, the largest protected area on the planet. As the detailed management plan for this park will be progressively established in the coming years, there is a local need for more information about marine mega-fauna space use in order to define key areas for wildlife conservation. Thus, the description of the humpback whales ecological niche in New Caledonian waters is the next logical step to initiate conservation planning. The effect of human activities needs to be investigated as the New Caledonian humpback whales population forms an isolated breeding sub-stock and is exposed to mining industry intensification, shipping, harbour construction and boat recreation associated to tourism development.

The general aim of my project is to investigate how humpback whales are using their habitat within and between reproductive areas of Oceania in order to facilitate their conservation at the scale of giant marine reserves (new generation of marine protected areas over vast surfaces exceeding hundreds of thousands of square kilometres). I will therefore focus on the spatial ecology of humpback whales in the New Caledonian Exclusive Economic Zone, with several specific aims:

1/ to quantify the spatio-temporal patterns and dynamics of humpback whale distribution in New Caledonian waters in order to identify key areas for the species and determine if these areas change over time or depending on social context.

2/ to assess the connectivity and movement patterns between areas of interest at individual scale.

3/ to document humpback whale use of habitat in relation to environmental factors and include these results in the broader-context of the South Pacific Ocean breeding areas.

4/ to provide a spatial and temporal assessment of the anthropogenic activities risks to humpback whales in New Caledonia.

I will rely on a large amount of data collected between 1991 and present, and provided by Opération Cétacés (an NGO involved in scientific research on humpback whales and other marine mammals in Oceania since 1996), including boat-based, land-based and aerial observations, satellite tracking and individual-based information (via Photo-Identification and genotyping).

This year, I am taking part in the summer field mission undergone by Opération Cétacés in the South Lagoon. I am currently living in Prony, a little village located along the southern coast of Grande Terre. No electricity, no internet, whale watching from 7am to 4pm on a daily basis: the real life!

In my next post I will tell you a bit more about this field trip with Opération Cétacés but for now, I will let you enjoy these few pictures!

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Prony Bay (© S. Derville)

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Rémi, Claire and Daisy standing next to the “Cap N’Dua” lighthouse from which land observations are made. Whales can be spotted up to 20 nautical miles offshore (© S. Derville) 

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View to the East of Cap N’Dua (© S. Derville)

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Breach observed a few days ago in the South Lagoon (© C. Garrigue)

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Inverted peduncle slap (the whale is lying upside down in the water and energetically slapping the surface with its fluke) (© S. Derville).

Surveying Harbor Porpoises on the Oregon Coast!

Hello Gemm lab readers!

Spring has officially made it to the Oregon coast.  The smells of blooming flowers are lingering in the air at the Hatfield Marine Science Center (HMSC), the seagulls are hovering around our afternoon BBQ’s, the local whale watching tour boats are zipping through the jetty’s to catch sight of all the whales still hovering in the area, and my team and I are right behind them as the field season is upon us in full force!

My name is Amanda Holdman and I am a master’s student in the Oregon State University’s Department of Fisheries and Wildlife and Marine Mammal Institute. Our lab, the geospatial ecology of marine megafuana, or GEMM lab for short, focuseharbor-porpoises_569_600x450s on the ecology, behavior and conservation of marine megafauna including cetaceans, pinnipeds, seabirds, and sharks. My research in particular is centered around the cetacean species that inhabit Oregon’s near coastal waters. While the cetacean order includes over 80 species, 30 of which can be found in Oregon, I am specifically targeting the small and charismatic harbor porpoise! I am hoping to answer questions about seasonal and diel patterns, and the drivers of these patterns to create a better understanding of the porpoise community off the coast of Newport.

To accomplish this, I have been using a couple different survey methods! Over the last year or so I have been conducting marine mammal visual surveys with a crew of observers, binoculars, cameras and lifejackets.  We’ve been very fortunate to work alongside and partner up with a number of labs and projects taking place at HMSC — including Sarah Henkel’s Benthic Ecology Lab, Jay Peterson’s Zooplankton Ecology Project, and Rob Suryan’s Seabird Oceanography Lab — who’ve invited us to share their boat time and join in on cruises to spot marine mammals. We had some motivating cruises with last year’s field season (bow riding pacific white sided dolphins and a possible fin whale sighting!) but now that the summer season is around the corner, It’s time to recruit additional observers and get everyone up to date on their safety certifications (at sea safety, first aid, etc.)

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While we currently have about 6-8 boat trips a month, I am not only just looking  for harbor porpoises, I’m also listening for them. To complement the visual surveys, I’ve added an acoustic component to my research, with the help of the Oregon State Research Collective for Applied Acoustics lab (ORCAA). This allows me to survey for harbor porpoises even under the worst sea conditions, when boat trips are unavailable. Odontocetes, such as the harbor porpoise use echolocation to navigate and forage and can be identified acoustically by their frequency range. While a full-depth analysis of last summer’s data hasn’t yet been accomplished, I was able to take a quick peek and MAN IT LOOKS GOOD! Both harbor porpoise and killer whale vocalizations were identified – you can check out the spectrogram below! This combination of using visual and acoustic surveys will help us answer when the porpoises are in our near waters, and where there primary hang-outs are!

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Visual representation of an echolocation clicks emitted by a feeding harbor porpoise

But springtime isn’t just for fieldwork, it’s also for course work! This quarter, my lab mate Erin Picket and I have enrolled into Julia Jones “Arcaholics anonymous” class, an introductory spatial statistics and GIS course that helps us piece together all the hard work we’ve put towards data collection to look for trends of animal distributions across space and time. This is the first time for both of us that we  get to upgrade our excel spreadsheets into a visual representation of our data! There will be more updates to come soon on how our projects are unfolding, but if you can’t wait til then, feel free to follow along with our class website!