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.

Celebrating Hydrothermal Vents!

By Florence Sullivan, MSc Student OSU

40 years ago, in 1977 OSU researchers led an NSF funded expedition to the Galapagos on a hunt for suspected hydrothermal vents. From the 1960s to the mid-1970s, mounting evidence such as (1) temperature anomalies found deep in the water column, (2) conduction heat flow probes at mid ocean ridges recording temperatures much lower than expected, (3) unusual mounds found on benthic mapping surveys, and (4) frequent, small, localized earthquakes at mid oceanic ridges, had the oceanographic community suspecting the existence of deep sea hydrothermal vents. However, until the 1977 cruise, no one had conclusive evidence that they existed.  During the discovery cruise at the Galapagos rift, the PI (principle investigator), Dr. Jack Corliss from OSU, used tow-yos (a technique where you drag a CTD up and down through the water in a zig zag pattern – see gif) to pinpoint the location of the hydrothermal vent plume. The team then sent the Deep Submergence Vehicle (DSV) Alvin to investigate and returned with the first photographs and samples from a hydrothermal vent. While discovery of the vent systems helped answer many questions about chemical and heat fluxes in the deep sea, it generated so many new questions that novel fields of study were created in biology, microbiology, marine chemistry, marine geology, planetary science, astrobiology and the study of the origin of life.

 “Literally every organism that came up was something that was unknown to science up until that time. It made it terribly exciting. Anything that came [up] on that basket was a new discovery,” – Dr. Richard Lutz (Rutgers University)

In celebration of this great discovery, OSU’s College of Earth, Ocean and Atmospheric Sciences sponsored a seminar looking at the past, present, and future of hydrothermal vent sciences. Dr. Robert Collier began with a timeline of how the search for hydrothermal vents began, and a commemoration of all the excellent researchers and collaborations between institutions and agencies that made the discovery possible. He acknowledged that such collaborations are often somewhat tense in terms of who gets credit for which discovery, and that while Oregon State University was the lead of the project, it takes a team to get the work done.  Dr. Jack Corliss proudly followed up with a wonderful rambling explanation of how vent systems work, and a brief dip into his ground breaking paper, “An Hypothesis concerning the relationship between submarine hot springs and the origin of life on Earth.” Published in 1981, with co-authors Dr. John Baross and Dr. Sarah Hoffman, they postulate that the temperature and chemical gradients seen at hydrothermal vents provide pathways for the synthesis of chemical compounds, formation and evolution of ‘precells’ and eventually, the evolution of free living organisms.

Dr. Corliss, Dr. Baross, and Dr. Hoffman were the first to suggest the now popular theory of the origin of life at hydrothermal vents. (click on image to read full paper)

Because of time constraints, the podium was swiftly handed over to Dr. Bill Chadwick (NOAA PMEL/ HMSC CIMRS) who brought us forward to the present day with an exciting overview of current vent research.  He began by saying “at the beginning, we thought, ‘No one has seen one of these systems before, they must be very rare…’ Now, we have found them [hydrothermal vents] in every ocean basin – including the arctic and southern oceans. We just needed to know how to look!”  Dr. Chadwick also reminded us that even 40 years later, new discoveries are still being made. For example, on his most recent cruise aboard the R/V Falkor in December 2016, they found a sulfur chimney that was alternately releasing bubbles of gas (sulfur, CO2 or other, hard to know without sampling) or bubbles of liquid sulfur! Check out the video below:

Some of the goals for this recent cruise included mapping new areas of the Mariana back-arc, and investigating differences in the biological communities between vents in the Mariana trench region (a subduction zone) and vents in the back arc (a spreading zone) to see if geology plays a role in biological community composition.  For some very cool video footage of the expedition and the various dives performed by the brand new ROV SUBastian (because all scientists love puns), check out the Schmidt Ocean Institute youtube channel.

Dr. Chadwick showed this video to highlight results from his last cruise.

Finally, Dr. Andrew Thurber wrapped up the session with some thoughts about hydrothermal vents from the perspective of an ecosystem services model. Even after 40 years of research, there are still many unknowns about these ecosystems.  Individual vent systems are inherently unique due to their deep sea isolation. However, most explored sites have revealed metals and mineral deposits that have generated a lot of interest from commercial sea floor mining companies. Exploitation of these deposits would be an example of ecosystem “provisioning services” (products that are obtained from the ecosystem). Other examples include the biology of the vents as a source of new genetic material, and the thermal and chemical gradients as natural laboratories that could lead to breakthroughs in pharmaceutical research. Cultural services are those non-material benefits that people obtain from an ecosystem. At hydrothermal vents these include new scientific discoveries, educational uses (British children’s television show “The Octonauts,” has several episodes featuring hydrothermal vent creatures), and creative inspiration for artists and others. Dr. Thurber cautions that there are ethical questions to be answered before considering exploitation of these resources, but there is a lot of potential for commercial and non-commercial use of vent ecosystems.

Vent inspired art by Lily Simonson

As an undergraduate at the University of Washington, I spent time as a research assistant in Dr. John Baross’ astrobiology lab. We studied evolutionary pathways of hydrothermal vent viruses and bacteria to inform the search for life on exoplanets such as Jupiter’s moon Europa.  It was very fun and exciting for me to attend this seminar, hear stories from pioneers in the field, and remember the systems I worked on in undergrad.  I may have moved up the food chain a little now, but as we all work on our pieces of the puzzle, it is important for scientists to remember the interdisciplinary nature of our work, and how there is always something more to learn.

 

 

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.

 

I love it when a plan comes together

By Dr. Leigh Torres

GEMM Lab

After four full-on days at sea covering 873 nautical miles, we are back in port as the winds begin to howl again and I now sip my coffee with a much appreciated still horizon. Our dedicated team worked the available weather windows hard and it paid off with more great absence data and excellent presence data too: blue whales, killer whales, common dolphins, and happily swimming pilot whales not headed to nearby Farewell Spit where a sad, massive stranding has occurred. It has been an exhausting, exhilarating, frustrating, exciting, and fulfilling time. As I reflect on all this work and reward, I can’t help but feel gratified for our persistent and focused planning that made it happen successfully. So, as we clean-up, organize data, process samples, and sit in port for a few days I would like to share some of our highlights over the past four days. I hope you enjoy them as much as we did.

The team in action on the RV Star Keys. Callum Lilley (DOC) on the bow waiting for a biopsy opportunity, Dawn Barlow (OSU) on the radio communicating with the small boat, Kristin Hodge (Cornell) taking photos of whales, Captain James Dalzell (Western Work Boats) on the helm, and Chief Engineer Spock (Western Work Boats) keeping his eyes peeled for a blow. (Photo credit: L. Torres)

 

In the small boat off looking for whales in a lovely flat, calm sea with an oil rig in the background. (Photo credit: D. Barlow)

 

Small boat action with Todd Chandler (OSU) at the helm, Leigh Torres (OSU) on the camera getting photo-id images, and Callum Lilley (DOC) taking the biopsy shot, and the dart is visible flying toward the whale in the black circle. (Photo credit: D. Barlow)

 

The stars of the show: blue whales. A photograph captured from the small boat of one animal fluking up to dive down as another whale surfaces close by. (Photo credit: L. Torres)

 

Collecting oceanographic data: Spock and Jason (Western Work Boats) deploy the CTD from the Star Keys. The CTD is an instrument that measures temperature, salinity, fluorescence and depth continuously as it descends to the bottom and back up again. (Photo credit: L. Torres)

 

The recently manufactured transducer pole in the water off the RV Star Keys (left) deployed with the echosounder to collect prey availability data, including this image (right) of krill swarms near feeding blue whales. (Photo credit: L. Torres)

 

The small boat returns to the Star Keys loaded with data and samples, including a large fecal sample in the net: The pooper scooper Leigh Torres (OSU), the biopsy rifle expert Callum Lilley (DOC), and the boat operator Todd Chandler (OSU). (Photo credit: D. Barlow)

 

Drone operator and videographer, Todd Chandler (OSU) under the towel (crucial piece of gear) to minimize glare on the screen as he locates and records blue whales. (Photo credit: K. Hodge)

 

A still shot captured from the drone footage of two adult blue whales surfacing in close proximity. (Photo credit: T. Chandler)

 

The team in action looking for blue whales in ideal survey conditions with Mt. Taranaki in the background. Todd Chandler (OSU) enters survey data while Dawn Barlow (OSU) spies for whale blows. (Photo credit: L. Torres)

 

A late evening at-sea after a big day sees Callum Lilley (DOC) processing a blue whale biopsy sample for transport, storage and analysis. (Photo credit: K. Hodge)

 

And we can’t forget why so many have put time, money and effort into this project: These blue whales are feeding and living within a space exploited by humans for multiple purposes, so we must ensure minimal impacts to these whales and their sustained health. (Photo credit: D. Barlow)

The worst summer ever!

By Dr. Leigh Torres

Geospatial Ecology of Marine Megafauna Lab

“This is the worst summer ever in New Zealand.” During our four days of prep in Wellington before heading off on our vessel, almost all my friends and colleagues I spoke to said this statement (often with added emphasis). It’s been cold and windy here all summer long, and when the weather has cleared it has brought only brief respite. These comments don’t bode well for our blue whale survey dependent on calm survey conditions, but February is typically the prime month for good weather in New Zealand so I’m holding out hope. And this unpredictable weather is the common denominator of all field work. Despite months (years?) of preparation, with minute attention to all sort of details (e.g., poop net handle length, bag size limits, length of deployment lines), one of the most important factors to success is something we have absolutely no control over: the weather.

After just one day on the water, I can see that the oceanographic conditions this year are nothing like the hot-water El Niño conditions we experienced last summer. Surface water temperatures today ranged between 12.8 and 13.6 ⁰C. These temps are 10 degrees (Celsius) cooler than the 22 ⁰C water we often surveyed last summer. 10 degrees! Additionally, the current windy conditions have stirred up the upper portion of the ocean water column causing the productive mixed layer to be much deeper (therefore larger) than last year. While Kiwis may complain about the ‘terrible’ weather this summer, the resulting cold and productive oceanographic conditions are likely preferable for the whales. But where are the whales and can we find them with all this wind?

Today we had a pocket of calm conditions so our dedicated research team and crew hit it with enthusiasm, and collected a whole lot of great absence data. “Absence data?” you may ask. Absence data is all the information about where the whales are not, and is just as important as presence data (information about where the whales are) because it’s the comparison between the two sets of data (Presence vs Absence) that allows us to describe an animal’s “habitat use patterns”. Today we surveyed a small portion of the South Taranaki Bight for blue whales for about 6 hours, but the only blue animals we saw were little blue penguins and a blue shark (plus fur seals, dolphins, albatrosses, shearwaters, gannets, prions, kahawai, and saury).  But during this survey effort we collected a lot of synoptic environmental data to describe these habitats, including continuous depth and temperature data along our track, nine CTD water column profiles of temperature, salinity and florescence (productivity) from the surface to the seafloor, and continuous prey (zooplankton) availability data with our transducer (echosounder).

So, now that we have absence data, we need presence data. But, the winds are howling again and are predicted to continue for the next few days. As we hunker down in a beautiful protected cove I know the blue whales continue to search this region for dense food patches, unencumbered by human-perceived obstacles of high wind and swell. So, while my Kiwi friends are right – this summer is not like previous years – I also know that it is the effects of these dynamic weather patterns that we have come so far, and worked so hard, to study. Even as my patience wears thin and my frustrations mount, I will continue to wait to pounce on the right weather window to collect our needed presence data (and more absence data too, I’m sure).

Our research team collecting absence data aboard the RV Star Keys:

Oceanus Day Three: Dolphin Delights

by Florence Sullivan, MSc student

Our third day aboard the Oceanus began in the misty morning fog before the sun even rose. We took the first CTD cast of the day at 0630am because the physical properties of the water column do not change much with the arrival of daylight. Our ability to visually detect marine mammals, however, is vastly improved with a little sunlight, and we wanted to make the best use of our hours at sea possible.

Randall Munroe www.XKCD.com

Our focus on day three was the Astoria canyon – a submarine feature just off the Oregon and Washington coast. Our first oceanographic station was 40 miles offshore, and 1300 meters deep, while the second was 20 miles offshore and only 170 meters deep.  See the handy infographic below to get a perspective on what those depths mean in the grand scheme of things.  From an oceanographic perspective, the neatest finding of the day was our ability to detect the freshwater plume coming from the Columbia River at both those stations despite their distance from each other, and from shore! Water density is one of the key characteristics that oceanographers use to track parcels of water as they travel through the ocean conveyor belt. Certain bodies of water (like the Mediterranean Sea, or the Atlantic or Pacific Oceans) have distinct properties that allow us to recognize them easily. In this case, it was very exciting to “sea” the two-layer system we had gotten used to observing overlain with a freshwater lens of much lower salinity, higher temperature, and lower density. This combination of freshwater, saltwater, and intriguing bathymetric features can lead to interesting foraging opportunities for marine megafauna – so, what did we find out there?

Click through link for better resolution: Randall Munroe www.XKCD.com/1040/large

Morning conditions were almost perfect for marine mammal observations – glassy calm with low swell, good, high, cloud cover to minimize glare and allow us to catch the barest hint of a blow….. it should come as no surprise then, that the first sightings of the day were seabirds and tuna!

I didn't catch any photos of the Tuna, so here's some mola mola we spotted. photo credit: Florence Sullivan
I didn’t catch any photos of the tuna, so here’s some sunfish we spotted. photo credit: Florence Sullivan

One of the best things about being at sea is the ability to look out at the horizon and have nothing but water staring back at you. It really drives home all the old seafaring superstitions about sailing off the edge of the world.  This close to shore, and in such productive waters, it is rare to find yourself truly alone, so when we spot a fishing trawler, there’s already a space to note it in the data log.  Ships at sea often have “follower” birds – avians attracted by easy meals as food scraps are dumped overboard. Fishing boats usually attract a lot of birds as fish bycatch and processing leftovers are flushed from the deck.  The birders groan, because identification and counts of individuals get more and more complicated as we approach other vessels.  The most thrilling bird sighting of the day for me were the flocks of a couple hundred fork-tailed storm petrels.

Fork-tailed storm petrels
Fork-tailed storm petrels. photo credit: Florence Sullivan

I find it remarkable that such small birds are capable of spending 80% of their life on the open ocean, returning to land only to mate and raise a chick. Their nesting strategy is pretty fascinating too – in bad foraging years, the chick is capable of surviving for several days without food by going into a state of torpor. (This slows metabolism and reduces growth until an adult returns.)

Just because the bird observers were starting to feel slightly overwhelmed, doesn’t mean that the marine mammal observers stopped their own survey.  The effort soon paid off with shouts of “Wait! What are those splashes over there?!” That’s the signal for everyone to get their binoculars up, start counting individuals, and making note of identifying features like color, shape of dorsal fin, and swimming style so that we can make an accurate species ID. The first sighting, though common in the area, was a new species for me – Pacific white sided dolphins!

Pacific white sided dolphin
A Pacific white sided dolphin leaps into view. photo credit: Florence Sullivan. Taken under NMFS permit 16111 John Calambokidis

A pod of thirty or so came to ride our bow wake for a bit, which was a real treat. But wait, it got better! Shortly afterward, we spotted more activity off the starboard bow.  It was confusing at first because we could clearly see a lot of splashes indicating many individuals, but no one had glimpsed any fins to help us figure out the species. As the pod got closer, Leigh shouted “Lissodelphis! They’re lissodelphis!”  We couldn’t see any dorsal fins, because northern right whale dolphins haven’t got one! Then the fly bridge became absolute madness as we all attempted to count how many individuals were in the pod, as well as take pictures for photo ID. It got even more complicated when some more pacific white sided dolphins showed up to join in the bow-riding fun.

Northern right whale dolphins are hard to spot! photo credit: Florence Sullivan Taken under NMFS permit 16111 John Calambokidis
Northern right whale dolphins are hard to spot! photo credit: Florence Sullivan Taken under NMFS permit 16111 John Calambokidis

All told, our best estimates counted about 200 individuals around us in that moment. The dolphins tired of us soon, and things continued to calm down as we moved further away from the fishing vessels.  We had a final encounter with an enthusiastic young humpback who was breaching and tail-slapping all over the place before ending our survey and heading towards Astoria to make our dock time.

Humpback whale breach
Humpback whale breach. photo credit: Florence Sullivan. Taken under NMFS permit 16111 John Calambokidis

As a Washington native who has always been interested in a maritime career, I grew up on stories of The Graveyard of the Pacific, and how difficult the crossing of the Columbia River Bar can be. Many harbors have dedicated captains to guide large ships into the port docks.  Did you know the same is true of the Columbia River Bar?  Conditions change so rapidly here, the shifting sands of the river mouth make it necessary for large ships to receive a local guest pilot (often via helicopter) to guide them across.  The National Motor Lifeboat School trains its students at the mouth of the river because it provides some of “the harshest maritime weather conditions in the world”.  Suffice it to say, not only was I thrilled to be able to detect the Columbia River plume in our CTD profile, I was also supremely excited to finally sail across the bar.  While a tiny part of me had hoped for a slightly more arduous crossing (to live up to all the stories you know), I am happy to report that we had glorious, calm, sunny conditions, which allowed us all to thoroughly enjoy the view from the fly bridge.

Cape Disappointment Lighthouse at the Columbia River Bar.
Cape Disappointment Lighthouse at the Columbia River Bar.

Finally, we arrived in Astoria, loaded all our gear into the ship’s RHIB (Ridged Hulled Inflatable Boat), lowered it into the river, descended the rope ladder, got settled, and motored into port. We waved goodbye to the R/V Oceanus, and hope to conduct another STEM cruise aboard her again soon.

Now if the ground would stop rolling, that would be just swell.

Last but not least, here are the videos we promised you in Oceanus Day Two – the first video shows the humpback lunge feeding behavior, while the second shows tail slapping. Follow our youtube channel for more cool videos!

 

Oceanus Day Two: All the Albatrosses

By Amanda Holdman and Florence Sullivan

Today got off to a bright and early start. As soon as daylight permitted, we had spotters out on duty looking for more marine mammals. We began to survey at the north end of Heceta bank, where we again encountered many humpback whales lunge feeding. We broke transect, and got some great video footage of a pair them – so check our youtube channel next week – we’ll upload the video as soon as we get back to better internet (dial up takes some getting used to again – the whales don’t know about highspeed yet).

Humpbacks lunge feeding at surface. photo credit: Leigh Torres. Taken under NMFS permit 16111 John Calambokidis.
Humpbacks lunge feeding at surface. photo credit: Leigh Torres. Taken under NMFS permit 16111 John Calambokidis.

After working with the humpbacks to capture photo-id data for about an hour, we turned south, and ran parallel to Heceta bank until we reached the southern edge. Along the way, we counted 30 humpbacks, and many California gulls, marbled murrelets, pink footed shearwaters, and sooty shearwaters.

After lunch, we conducted a CTD cast to see how conditions might be different between the southern and northern edges of the bank. Surface temperatures increased from 12.09C to 13.2C while bottom temperatures decreased from 8.7C to 7.8C.  The northern station was a textbook perfect two layer system. It had a well mixed surface layer with a steep pycnocline separating it from the colder, saltier, denser, bottom layer. The southern station still had two layers, but the pycnocline (the depth where a rapid change in density occurs, which delineates the edges of water masses) was not as steep. We are interested in these discreet measurements of ocean conditions because areas of high primary productivity (the green chlorophyll-a line) are often re-occurring hot spots of food for many levels of the food chain. Since we can’t phone the whales and ask them where to meet up, we use clues like these to anticipate the best place to start looking.

Readout of the CTD cast. The left plot has temperature in blue, and salinity in green. The right plot has density in black, chlorophyll-a in green, and oxygen in blue. observe how different variables change with depth!
Readout of the CTD cast. The left plot has temperature in blue, and salinity in green. The right plot has density in black, chlorophyll-a in green, and oxygen in blue. observe how different variables change with depth (on the y-axes)!

We next turned west to transect the continental shelf break. Here, we were hoping to observe changes in species composition as waters got deeper, and habitat changed.  The shelf break is often known as an area of upwelling and increased primary productivity, which can lead to concentrations of marine predators taking advantage of aggregations of prey. As we moved further offshore, everyone was hoping for some sperm whales, or maybe some oceanic dolphin species, and if we’re really lucky, maybe a beaked whale or two.

Black footed Albatross with immature gulls. photo credit: Leigh Torres
Black footed Albatross with immature gulls. photo credit: Leigh Torres

Today our students learned the lesson of how difficult marine mammal observation can be when our target species spend the majority of their lives underwater – where we can’t see them. While there were a couple of hours of mammal empty water in there, observers were kept busy identifying long tailed- jaegers, cassin’s auklets, murrelets, petrels, shearwaters, fulmars, and so many black-footed albatrosses, that they almost became “normal”.  That being said, we did spot a fin whale, a few groups of Dall’s porpoise, and three pacific-white-sided dolphins.  Unexpectedly, we also saw an unidentified shark, and several sunfish (mola mola)!

Humpback whale profile. photo credit: Amanda Holdman. Taken under NMFS permit 16111 John Calambokidis.
Humpback whale profile – notice the hump before the dorsal fin. photo credit: Amanda Holdman. Taken under NMFS permit 16111 John Calambokidis.
Fin Whale profile. photo credit: Amanda Holdman. Taken under NMFS permit 16111 John Calambokidis.
Fin Whale profile – notice how long the back is before the fin, and how pointed the dorsal fin is compared to the humpback. photo credit: Amanda Holdman. Taken under NMFS permit 16111 John Calambokidis.

Last but not least, we engaged in a long standing oceanographic tradition, which is to draw on Styrofoam cups, and send them down to Davy Jone’s Locker attached to the CTD.  When you bring them back up, the pressure has caused them to shrink to a fraction of their original size, which is an excellent demonstration of the crushing power of pressure (and why its harder to build a submarine than a rocket).

Shrunken cups! The first row have been sent down to 1400m, while the back row are still full size!
Shrunken cups! The first row have been sent down to 1400m, while the back row are still full size!

Now, we are steaming north toward Astoria Canyon, where we hope to make some more sightings in the morning. Stand by for news from our final day at sea.

Fin Whale. photo credit Amanda Holdman. Taken under NMFS permit 16111 John Calambokidis.
Fin Whale. photo credit Amanda Holdman. Taken under NMFS permit 16111 John Calambokidis.
Dahl's Porpoise. photo credit: Florence Sullivan. Taken under NMFS permit 16111 John Calambokidis.
Dahl’s Porpoise. photo credit: Florence Sullivan. Taken under NMFS permit 16111 John Calambokidis.

Scratching the Surface

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

I have been reminded of a lesson I learned long ago: Never turn your back on the sea – it’s always changing.

The blue whales weren’t where they were last time. I wrongly assumed oceanographic patterns would be similar to our last time out in 2014 and that the whales would be in the same area. But the ocean is dynamic – ever changing. I knew this. And I know it better now.

Below (Fig. 1) are two satellite images of sea surface temperature (SST) within the South Taranaki Bight and west coast region of New Zealand that we surveyed in Jan-Feb 2014 and again recently during Jan-Feb 2016. The plot on the left describes ocean surface conditions in 2014 and illustrates how SST primarily ranged between 15 and 18 ⁰C. By comparison, the panel on the right depicts the sea surface conditions we just encountered during the 2016 field season, and a huge difference is apparent: this year SST ranged between 18 and 23 ⁰C, barely overlapping with the 2014 field season conditions.

Figure 1. A comparison of satellite images of sea surface temperature (SST) in the South Taranaki Bight region of New Zealand between late January 2014 and early February 2016. The white circles on each image denote where the majority of blue whales were encountered during each field season.
Figure 1. A comparison of satellite images of sea surface temperature (SST) in the South Taranaki Bight region of New Zealand between late January 2014 and early February 2016. The white circles on each image denote where the majority of blue whales were encountered during each field season.

While whales can live in a wide range of water temperatures, their prey is much pickier. Krill, tiny zooplankton that blue whales seek and devour in large quantities, tend to aggregate in pockets of nutrient-rich, cool water in this region of New Zealand. During the 2014 field season, we encountered most blue whales in an area where SST was about 15 ⁰C (within the white circle in the left panel of Fig. 1). This year, there was no cool water anywhere and we mainly found the whales off the west coast of Kahurangi shoals in about 21 ⁰C water (within the white circle in the right panel of Fig. 1. NB: the cooler water in the Cook Strait in the southeast region of the right panel is a different water mass than preferred by blue whales and does not contain their prey.)

The hot water we found this year across the survey region can likely be attributed, at least in part, to the El Niño conditions that are occurring across the Pacific Ocean currently. El Niño has brought unusually settled conditions to New Zealand this summer, which means relatively few high wind events that normally churn up the ocean and mix the cool, nutrient rich deep water with the hot surface layer water. These are ideal conditions for Kiwi sun-bathers, but the ocean remains highly stratified with a stable layer of hot water on top. However, this stratification does not necessarily mean the ocean is un-productive – it only means that the SST satellite images are virtually useless for helping us to find whales this year.

Although SST data can be informative about ocean conditions, it only reflects what is happening in the thin, top slice of the ocean. Sub-surface conditions can be very different. Ocean conditions during our two survey periods in 2014 and 2016 could be more similar when compared underwater than when viewed from above. This is why sub-surface sensors and data collection is critical to marine studies. Ocean conditions in 2014 and 2016 could both potentially provide good habitat for the whales. In fact, where and when we encountered whales during both 2014 and 2016 we also detected high densities of krill through hydro-acoustics (Fig. 2). However, in 2014 we observed many surface swarms of krill that we rarely saw this recent field season, which could be due to elevated SST. But, we did capture cool drone footage this year of a brief sub-surface foraging event:

An overhead look of a blue whale foraging event as the animal approaches the surface. Note how the distended ventral (throat) grooves of the buccal cavity (mouth) are visible. This is a big gulp of prey (krill) and water. The video was captured using a DJI Phantom 3 drone in the South Taranaki Bight of New Zealand in on February 2, 2016 under a research permit from the New Zealand Department of Conservation (DOC) permit # 45780-MAR issued to Oregon State University.

Figure 2. An echo-sounder image of dense krill patches at 50-80 m depth captured through hydroacoustics in the South Taranaki Bight region of New Zealand.
Figure 2. An echo-sounder image of dense krill patches at 50-80 m depth captured through hydroacoustics in the South Taranaki Bight region of New Zealand.

Below are SST anomaly plots of January 2014 and January 2016 (Fig. 3). These anomaly plots show how different the SST was compared to the long-term average SST across the New Zealand region. As you can see, in 2014 (left panel) SST conditions in our study area were ~1 ⁰C below average, while in 2016 (right panel) SST conditions were ~1 ⁰C above average. So, what are normal conditions? What can we expect next year when we come back to survey again for blue whales across this region? These are challenging questions and illustrate why marine ecology studies like this one must be conducted over many years. One year is just a snap shot in the lifetime of the oceans.

Figure 3. Comparison of sea surface temperature (SST) anomaly plots of the New Zealand region between January 2014 (left) and January 2016 (right). The white box in both plots denotes the general location of our blue whale study region. (Apologies for the different formats of these plots - the underlying data is directly comparable.)
Figure 3. Comparison of sea surface temperature (SST) anomaly plots of the New Zealand region between January 2014 (left) and January 2016 (right). The white box in both plots denotes the general location of our blue whale study region. (Apologies for the different formats of these plots – the underlying data is directly comparable.)

Like all marine megafauna, blue whales move far and fast to adjust their distribution patterns according to ocean conditions. So, I can’t tell you what the ocean will be like in January 2017 or where the whales will be, but as we continue to study this marine ecosystem and its inhabitants our understanding of ocean patterns and whale ecology will improve. With every year of new data we will be able to better predict ocean and blue whale distribution patterns, providing managers with the tools they need to protect our marine environment. For now, we are just beginning to scratch the (sea) surface.

 

 

 

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.