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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.

Wildlife of the Western Antarctic Peninsula

Erin Pickett, MS Student, Fisheries and Wildlife Department, OSU

This time last week, I was on a research vessel crossing the Drake Passage. The Drake extends from the tip of the Western Antarctic Peninsula to South America’s Cape Horn, and was part of the route I was taking home from Antarctica. Over the past three months I have been working on a long-term ecological research (LTER) project based out of Palmer Station, a U.S. based research facility located on Anvers Island.

Image: http://www.tetonat.com/2009/11/06/bon-voyage-off-to-antarctica-with-iceaxe-expeditions/
Image: http://www.tetonat.com/2009/11/06/bon-voyage-off-to-antarctica-with-iceaxe-expeditions/

While in Antarctica, I was working on the cetacean component of the Palmer LTER project, which I’ve described in previous blog posts. In lieu of writing more about what it is like to work and live on the Antarctic Peninsula, I thought I’d share some photos with you. Working on the water everyday while searching for whales provided me with many opportunities to photograph the local wildlife. I hope you’ll enjoy a few of my favorite shots.

A porpoise-full lesson on cetacean identification

By Amanda Holdman, M.S. student

The rain is beginning to lighten, the heavy winds are starting  to dissipate, and the sun is beginning to shine. Seabirds are starting to fill the air and marine mammals are starting to fill the coastline, making this week a perfect time to learn about some of the small, cryptic cetaceans that consider the Oregon coast home year round.

While I was walking my dog on South Beach in Newport last week, I heard the mother of a small family point and shout that she had just seen an animal that she referred to as a “porpoise/dolphin/small whale.” Upon a second sighting of it, she ruled against the small whale and decided on a dolphin. In reality, she had just sighted a harbor porpoise.

Throughout the duration of my work with Oregon State studying the patterns of harbor porpoise occurrence, one of the most frequently asked questions I get is “What is the difference between a porpoise and a dolphin?”

Differentiating between a dolphin and porpoise is probably the most common identification mistake when it comes to cetaceans. Understandably, there is significant confusion between the two species. The words dolphin and porpoise were, colloquially, used as synonyms until the 1970’s. Unlike lions and tigers that are not only in the same family, but also the same genus, dolphins and porpoises are in different families, having diverged evolutionarily about 15 million years ago! Therefore, dolphins and porpoises are more distinct than lions and tigers. These differences span from head and fin shape, to behavior, group size and vocals.

Physical Differences

Most people are quite certain they are seeing a dolphin mainly because dolphins are more prevalent than porpoises; over 30 species of dolphins are known to exist, but only 6 porpoise species have been identified worldwide. Unless, you’ve seen dolphins and porpoises side by side, nose to fin, it is quite difficult to tell the difference at first glance. In the natural history of cetacean’s course at Oregon State, we are taught that the three main visual differences are in the shape of the teeth, snout, and dorsal fin. But in reality, the first two characteristics aren’t likely to help you spot them from shore. In addition to fin size, the behavior and group size is more likely to cue you in on what animal you are seeing. The picture below does a pretty good job summarizing their physical characteristics. Porpoise have a small triangle fin, while dolphins have more of a curved, pointy fin.

identificationDrawing by Mike Rock, 2009.

Size Differences

The lengths and widths of dolphins vary anywhere from 4 feet to 30 feet. Killer whales, the largest dolphin species and known predator to the harbor porpoise, can weigh up to ten tons, while the harbor porpoise is about five feet and rarely weighs in over 150 pounds.  Porpoises are one of the smallest cetaceans, and because of their small size, they lose body heat to the water more quickly than other cetaceans. Their blunt snout is likely an adaptation to minimize surface area to conserve heat. The small sizes of porpoise require them to eat frequently, rather than depending on fat reserves, making them more of an opportunistic feeder. The need to constantly forage also keeps harbor porpoise from migrating on a large scale. Harbor porpoise are known to move from onshore to offshore waters with changing water temperatures and prey distributions, but not known to make long migration trips.

Social Differences

Porpoises are also less social and talkative than dolphins. Dolphins are typically found in large groups, can be highly acrobatic, and often seen bow-riding. Porpoise, specifically harbor porpoise, are often found singularly or in groups of two to three, and shy away from vessels, making them difficult to observe at sea. While both species have large melon heads for echolocation purposes, dolphins make whistles through there blow holes to communicate with each other underwater. Evolutionary scientists believe porpoises do not whistle due to structural differences in their blowhole. (This is why acoustics is such a great way to learn about the occurrence patterns of harbor porpoise – their echolocation is very distinct!) Porpoise echolocation signals have evolved into a very narrow frequency range – theoretically to protect themselves from killer whale predation by echolocating at a frequency killer whales cannot hear.  Dolphins have evolved other strategies to avoid predators such as large group size and fast speed.

While differentiating between porpoises and dolphins takes a bit of practice, it is important to differentiate between the two species because we manage them differently due to some of their morphological differences. Their different adaptations between the species make them more sensitive to certain stressors. For example, for harbor porpoise, the sound produced from boat noise or renewable energy devices is more likely to impact them than other cetaceans. The sensitivity of the nerve cells in the ears of animals (including humans) generally corresponds to the frequencies that each animal produces. So animals like the harbor porpoise have more nerves in their ears that are tuned to very high frequencies (since they make high frequency sounds). If the nerve cells in the harbor porpoise ears become damaged, their ability to communicate, navigate and find food is seriously affected. In addition to their small home ranges and moderately high position in the food web, the sensitivity of harbor porpoise to ocean noise levels make harbor porpoise an important indicator species for ecosystem health, and an important species to study on the Oregon Coast.

Smile! You’re on Camera!

By Florence Sullivan, MSc. Student, GEMM Lab

Happy Spring everyone!  You may be wondering where the gray whale updates have been all winter – and while I haven’t migrated south to Baja California with them, I have spent many hours in the GEMM Lab processing data, and categorizing photos.

You may recall that one of my base questions for this project is:

Do individual whales have different foraging strategies?

In order to answer this question, we must be able to tell individual gray whales apart. Scientists have many methods for recognizing individuals of different species using tags and bands, taking biopsy samples for DNA analysis, and more. But the method we’re using for this project is perhaps the simplest: Photo-Identification, which relies on the unique markings on individual animals, like fingerprints.  All you need is a camera and rather a lot of patience.

Bottlenose dolphins were some of the first cetaceans to be documented by photo-identification.  Individuals are identified by knicks and notches in their fins. Humpback whales are comparatively easy to identify – the bold black and white patterns on the underside of their frequently displayed flukes are compared.  Orcas, one of the most beloved species of cetaceans, are recognized thanks to their saddle patches – again, unique to each individual. Did you know that the coloration and shape of those patches is actually indicative of the different ecotypes of Orca around the world? Check out this beautiful poster by Uko Gorter to see!

Gray whale photo identification is a bit more subtle since these whales don’t have dorsal fins and do not show the undersides of their fluke regularly.  Because gray whales can have very different patterns on either side of their body, it is also important to get photos of both their right and left sides, as well as the fluke, to be sure of recognizing an individual if it comes around again.   When taking photos of a gray whale, it’s a good idea to include the dorsal hump, where the knuckles start as it dives, as an easy indicator of which side of the body you are looking at when you’re trying to match photos.  Some clues that I often use when identifying an individual include the placement of barnacles, and patterns of pigmentation and scars.  You can see that patience and a talent for pattern recognition come in handy for this sort of work.

While we were in the field, it was important for my team to quickly find reference features to make sure we were always tracking the same whale. If you stopped by to visit our field station, you may have heard use saying things like “68 has white on both fluke-tips”, “70 has a propeller scar on the left side”,  “the barnacles on 54’s head looks like a polyp”, or “27 has a smiley face in front of the first knuckle left side.” Sometimes, if a trait was particularly obvious, and the whale visited our field station more than once, we would give them a name to help us remember them.  These notes were often (but to my frustration, not always!) recorded in our field notebook, and have come in handy this winter as I have systematically gone through the 8000+ photos we took last summer, identifying each individual, and noting whenever one was a repeat visitor. With these individuals labeled, I can now assess their level of behavioral and distribution consistency within and between study sites, and over the course of the summer.

Why don’t you try your luck?  How many individuals are in this photoset? How many repeats?  If I tell you that my team named some of these whales Mitosis, Smiley, Ninja and Keyboard can you figure out which ones they are?

#1
#2
#2
#3
#4
#4
#5
#5
#6
#6
#7
#7
#8
#8
#9
#9
#10
#10

 

Keep scrolling for the answer key ( I don’t want to spoil it too easily!)

 

 

 

 

 

Answers:

There are 7 whales in this photoset. Smiley and Keyboard both have repeat shots for you to find, and Smiley even shows off both left and right sides.

  1. Whale 18 – Mitosis
  2. Whale 70 -Keyboard
  3. Whale 23 -Smiley
  4. Whale 68 – Keyboard
  5. Whale 27 -Smiley
  6. Whale 67
  7. Whale 36 -Ninja
  8. Whale 60 – “60”
  9. Whale 38 – has no nickname even if we’ve seen it 8 times! Have any suggestions? leave it in the comments!
  10. Whale 55 – Smiley

 

Midway Atoll: Two weeks at the largest albatross colony in the world

By Rachael Orben, Postdoctoral Scholar, Seabird Oceanography Lab & Geospatial Ecology of Marine Megafauna Lab, Oregon State University

In January I was extremely lucky to accompany my former PhD advisor, Scott Shaffer to Midway Atoll National Wildlife Refuge in the Papahānaumokuākea Marine National Monument as part of my job as a postdoc working in Rob Suryan’s Seabird Oceanography Lab. We were there with the dual purpose of GPS tracking Laysan and Black-footed albatrosses as part of Scott’s long-term research and to collect fine-scale data on flight behavior to develop collision risk models for wind energy development (in other areas of the species ranges such as Oregon). Here are my impressions of this amazing island.

So many albatrosses! Our approximately four hour flight from Honolulu to Midway landed at night and as we stood around on the dark tarmac greeting the human island residents I could just make out the ghostly glistening outlines of albatrosses by moonlight. But I had to wait until the following morning to really take stock of where I had suddenly landed: Midway Atoll, the largest albatross colony in the world. This was my first trip to the Northwestern Hawaiian Islands, but I have been to other albatross colonies before and Midway is most definitely different.

First of all, it was hot(ish)!

Secondly, I was amazed to see albatrosses nesting everywhere. Unlike the southern hemisphere colonies I have visited, the albatrosses aren’t restricted to their section of the island or even nesting as close to each other as possible. Instead there are nests literally everywhere there might be enough loose substrate! Birds nest in the middle of the roads, in the bike racks (bikes are an easy quick means of transportation), along the paths, next to the extremely loud generator, near piles of old equipment, and around buildings. Hawaiian albatross nests are not much to look at compared to the mud pedestal nests of the southern hemisphere mollymawks (see the photos below) and are often made of just enough sand and vegetation to keep the egg in place. There are no aerial predators of these birds, beyond the occasional vagrant peregrine, and certainly nothing that might rival the tenacity of the skuas in the southern hemisphere. Perhaps it is this naiveté that has lead to their willingness to nest anywhere.

It may also be this naiveté that has facilitated the following unfortunate turn of events. Just before I arrived, the USFWS and a crew of volunteers had just finished up the annual albatross count. During their counting sweeps they noticed injured adults incubating eggs. After setting out trail cams, suspicions were confirmed. The introduced mice on Midway have discovered that albatrosses are a source of food. House mice are known to prey on albatross chicks on Gough and Marion Islands in the South Atlantic (more information here – warning graphic photos), but to my knowledge this is the first time that they have started eating adult birds. You can read the USFWS announcement here. The plane that I flew out on brought in people, traps, and resources to deal with the situation, but stay tuned as I fear this saga is just beginning.

Finally, and on a further less than positive note, I went to Midway fully aware of the problem that plastics pose to these birds and our marine ecosystem, but there is something to be said for seeing it first hand. The chicks were very small when I was there so I didn’t see any direct impacts on them, but see below for photos of carcasses of last year’s fledglings with plastic filled stomachs. Instead, it was the shear amount of random plastic bits strewn around the island and buried layers deep into the sand that struck me. I learned that sometimes the plastic bits are glow-in-the-dark! Sometimes fishing lures have batteries in them – I am not sure what they are used to catch – do you know? And toothbrushes are very common. All of the plastic that I saw among the birds arrived in the stomach of an adult albatross. All-in-all the experience gave me renewed inspiration for continuing to reduce the amount of plastic that I use (click here for more information on albatrosses and plastic, and here and here for info on marine plastic pollution in general). I collected interesting pieces to bring home with me (see the photos below), but it is a non-random sampling of what caught my eye. I left many many plastic shards where they were.

I have written mostly about the birds, but Midway is full of human history. As I biked along the runway, or past the old officer quarters, I often found myself wondering what all these albatrosses have seen over the years and what they might witness in the future. Two weeks was really just a blink-of-an-eye for an albatross that can live over 40 years (or longer like Wisdom the albatross). I was terribly sad to leave such a beautiful place, but I came home with amazing memories, photos, and gigabytes of data that are already giving me a glimpse into the world of albatrosses at sea.

Racing blues

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

A week ago we observed two racing blue whales.

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

 

Marine Megafauna Ecology Fund

 

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.

An update from the Antarctic Peninsula

By: Erin Pickett

Yesterday someone said to me, “I don’t know if it was sunrise or sunset, but it was beautiful”. So it goes on the R/V Lawrence M. Gould (LMG), the surrounding scenery is incredible but the work schedule on this research ship makes it difficult to remember what time of day it is.

Here on the Antarctic Peninsula, the sun never really sets and our daily schedules are dependent on things like the diel vertical migration of krill, the current wind speed and the amount of sea ice in between us and our study species, the humpback whale. For these reasons, we sometimes find ourselves starting our workday at odd hours, like 11:45 pm (or 4:00 am). As a reminder, I am currently working on research vessel on a project called the Palmer long term ecological research (LTER) project.  You can read my first blog post about that here. We are about one week into our journey and so far, so good!

Our journey began in Punta Arenas, Chile, where we spent two days loading our research supplies onto the LMG and getting outfitted with cold weather gear. From Punta Arenas we headed south through the straights of Magellan and then across the Drake Passage. Along the way we spotted a variety of cetaceans including minke, fin, sei and humpback whales, and Commerson’s and Peale’s dolphins. I spent as much of our time in transit as I could looking for seabirds, the most numerous being white-chinned and cape petrels, southern giant petrels, and black-browed albatrosses. Spotting either a royal or a wandering albatross was always exciting. An eleven foot wingspan allows these albatross to glide effortlessly above the water and this makes for a beautiful sight!

We have spent the last four days transiting between various sampling stations around Palmer deep, which is an underwater canyon just south of our home base at Palmer station. When conditions allowed, we loaded up our tagging and biopsy gear into a small boat and went to look for humpback whales. We’ve been incredibly successful with the limited amount of time we’ve had on the water and this morning we finished deploying our sixth tag.

We brought a few different types of satellite tags with us to deploy on humpback whales. One type is an implantable satellite tag that transmits location data over a long period of time. These data allow us to gain a better understanding of the large-scale movement and distribution patterns of these animals. The other tag we deploy is a suction cup tag, so called because four small suction cups attach the tag to the whale. These suction cup tags are multi-sensor tags that measure location as well as fine scale underwater movement (e.g. pitch, roll, and heading). They are also equipped with forward and backward facing cameras and most importantly, radio transmitters! This allows us to recover the tags once they fall off the animal and float to the surface (after about 24 hours). The data we get from these tags will allow us to quantify fine-scale foraging behavior in terms of underwater maneuverability, prey type and the frequency, depth and time of day that feeding occurs.

When we deployed each of these tags we also obtained a biopsy sample and fluke photos. Fluke photos and biopsy samples allow us to distinguish between individual animals, and the biopsy samples will also be used to study the demographics of this population through genetic analysis.

Now that we’ve deployed all of our satellite tags and have recovered the suction cup tag just in the nick of time (!), we are starting our first major transect line toward the continental shelf. We will be continuing south along these grid lines for the next week.

My lab mate Logan Pallin and I will be continuing to write about our trip over the next couple of months on another blog we created especially for this project. You can find it here: blogs.oregonstate.edu/LTERcetaceans

I’ll leave you with a few of my favorite photos of the trip so far!

Behind the scenes of modeling

By Olivia Hamilton, PhD Candidate, Institute of Marine Science,

University of Auckland

I am going to take you behind the scenes of modeling. No, I do not mean the kind of modeling where six-foot tall glamazons such as Cindy Crawford get paid exorbitant amounts of money to dress up in fabulous outfits, strike a pose, and attend A-list parties. I am talking about statistical modeling. This usually involves wearing sweatpants, sitting at your computer for extended periods of time, and occasionally turning to a block of chocolate for comfort.

Species distribution models (SDM), also known as habitat models, are a powerful tool for informing conservation and management of animal populations. They essentially enable us to identify important areas of habitat by describing the relationship between the spatial distribution pattern of a species and the attributes of their physical environment. It is logistically difficult to observe top marine predators such as whales, dolphins, sharks, and seabirds. This difficulty is because a) they move, and b) we only get to observe them during the small portion of their lives that they spend near or at the surface of the water. Environmental variables such as water depth and slope do not necessarily influence the habitat use patterns of top predators directly, but we can use them in our models as proxies for more important ecological determinants of habitat use that are more difficult to collect data for, such as the distribution of their prey.

Some SDM take this a step further by enabling us to make predictions about a species’ distribution in areas or time periods that we did not survey. This predictive capacity can provide us with a more holistic understanding of their how animals use their range, and the ability to anticipate distribution patterns under variable conditions (think climate change 100 years from now).

The idea of understanding how sharks, dolphins, whales, and seabirds are using the Hauraki Gulf in New Zealand is an extremely exciting prospect for a nosy biologist like me. I have always had a fascination with mega-fauna, and more specifically with large predators. To me, uncovering the reasons that drive their habitat use patterns is the equivalent to finding a pearl in an oyster. However, that’s just me being selfish. The best thing about creating predictive habitat models for mega-fauna in the Gulf is that we will gain a better understanding of how to manage and protect them. The SDM that I am using are called Boosted Regression Trees (BRT). They are a relatively new kid on the habitat modeling block, but are recognized as a powerful tool for making habitat predictions with. Dream result.

My Master’s thesis had a focus on abundance estimates and social structure analyses; everything I have learned about habitat modelling while in the GEMM Lab at Oregon State University was from scratch. One of the largest lessons that I learned was how much behind the scenes preparation is needed before you can even get to the actual modeling point. The length of the preparation stage is proportional to the size of the dataset. Needless to say, the years’ worth of multi-species aerial survey data that I have collected has kept me quite busy.

The first step was to create pseudo-absences.

Pseudo-what you say?

When we are out on the water, or in the plane, and we see animals of interest, we record their geographic location. As a result, our presence sightings are represented as points in space. However, in order to identify areas of preferred habitat we need to also describe the range of environmental conditions that are available to the population. To do this, we also need to obtain environmental data from where animals were not seen, otherwise known as absence data. As I mentioned earlier, observing marine animals is difficult. This makes it difficult to obtain confirmed absence data. Luckily, some savvy scientists came up with the idea of creating pseudo-absences. The idea is to basically use the area in which sightings were not made to generate randomly placed absence points.

As simple as that?

Of course not.

When generating pseudo-absences, we want to make sure that they are placed in areas that reflect true absences. Poor environmental conditions affect our ability to detect animals, especially when travelling along at 160km/h at 500ft in a small plane. After making some exploratory plots of the various environmental conditions relative to sighting frequencies, we identified what conditions hindered our ability to see animals (Fig. 1 & 2). Stretches of the track that we flew in poor conditions were then removed before generating the pseudo-absences.

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Fig. 1. Example of exploratory plots looking at the relationship between detection rates and the amount of glare coverage within our viewing area. Fig. 2. shows that very few detections of common dolphins were made when the glare coverage exceeded 60% and 3 shows that detection rates for gannets were acceptable up to 80% glare coverage. Any stretches of a particular survey that exceeded these values were excluded before pseudo-absences were generated.

The next step was to decide where to place the pseudo-absences along the track-lines. To do this, we used all sightings data for each species to create density plots (Fig. 2), and then distributed our pseudo-absences in an inverse proportion to their density (Fig. 3). That way, we were distributing a higher number of absences in areas of known lower density, and therefore obtaining a representative sample of environmental variables in areas that reflected true absences.olivia2Fig. 2: Density plot of all common dolphin sightings over 22 aerial surveys in the Hauraki Gulf. Red represents the highest density and blue represents the lowest density.

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Fig. 3:  Aerial track-lines flown in the Hauraki Gulf, New Zealand on 19 March 2014. Triangle symbols represent pseudo-absences and black circles represent presence sightings for that day.

Next what?

Step two involved creating environmental layers that would be included as predictor variables in our models. Instead of chucking any old variable in there, we needed to decide what physical or biological features of the environment would be ecologically relevant for explaining the different species distributions. For example, one of the variables we are using is tidal height/flow. Tidal movement pushes around potential food for marine animals and therefore influences how they use their space.  Some others environmental variables included in our models were proximity to potential prey patches (zooplankton and fish), sea surface temperature, and the type of substrate (sand, mud, gravel).

Finally, we are ready for the main event. Ladies and gentlemen, I introduce to you preliminary results for one of my study species, the Nationally Endangered Bryde’s whale (Fig. 4). These plots show us the relative influence of each the environmental variables on the distribution of Bryde’s whales in the Hauraki Gulf. The percentage value associated with each of the plots tells us how much influence each variable had in the model. We can see that the time of the year (month), the distribution of food (zooplankton and fish), and the difference in water temperature over the year have the most influence on the distribution of Bryde’s whales. This makes complete ecological sense. Prey distribution is one of the main ecological drivers of the distribution of predators both in time and space. Temperature is one of the main drivers for the distribution of prey species. As the water temperature changes throughout the year within the Gulf, so does the availability of the Bryde’s whales prey items. In turn, this influences how much time they spend in the Gulf. When prey is around, the Bryde’s whales are never far away. Eating is a very important part of the day for these 90,000 lbs whales; therefore it pays to stay close to their food supply.

Olivia4Fig. 4: Relative influence of environmental predictors on the distribution of Bryde’s whales within the Hauraki Gulf, New Zealand.

The show is not over yet, folks. While the code is all running smoothly, there is still a bit of fine-tuning to do. I am currently working on this, re-running these models over and over, trying to iron out the creases. At the moment, I am creating SDMs for four of my study species: Bryde’s whales, common dolphins, bronze whaler sharks, and gannets. Once we are satisfied with how things are running, I will start stage two of the modeling process: the prediction maps.

Next year, we will conduct several more aerial surveys in the Hauraki Gulf with the aim of validating our habitat models.

How is that for a cliffhanger?

Stay tuned to gain an insight into the habitat use of mega-fauna in the Hauraki Gulf, New Zealand.

Exciting news for the GEMM Lab: SMM conference and a twitter feed!

By Amanda Holdman (M.S Student)

At the end of the week, the GEMM Lab will be pilling into our fuel efficient Subaru’s and start heading south to San Francisco! The 21st Biennial Conference on the Biology of Marine Mammals, hosted by the Society of Marine Mammalogy, kicks off this weekend and the GEMM Lab is all prepped and ready!

Workshops start on Saturday prior to the conference, and I will be attending the Harbor Porpoise Workshop, where I get to collaborate with several other researchers worldwide who study my favorite cryptic species. After morning introductions, we will have a series of talks, a lunch break, and then head to the Golden Gate Bridge to see the recently returned San Francisco harbor porpoise. Sounds fun right?!? But that’s just day one. A whole week of scientific fun is to be had! So let’s begin with Society’s mission:

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‘To promote the global advancement of marine mammal science and contribute to its relevance and impact in education, conservation and management’ 

And the GEMM Lab is all set to do just that! The conference will bring together approximately 2200 top marine mammal scientists and managers to investigate the theme of Marine Mammal Conservation in a Changing World. All GEMM Lab members will be presenting at this year’s conference, accompanied by other researchers from the Marine Mammal Institute, to total 34 researchers representing Oregon State University!

Here is our Lab line-up:

Our leader, Leigh will be starting us off strong with a speed talk on Moving from documentation to protection of a blue whale foraging ground in an industrial area of New Zealand

Tuesday morning I will be presenting a poster on the Spatio-temporal patterns and ecological drivers of harbor porpoises off of the central Oregon coast

Solène follows directly after me on Tuesday to give an oral presentation on the Environmental correlates of nearshore habitat distribution by the critically endangered Maui dolphin.

Florence helps us reconvene Thursday morning with a poster presentation on her work, Assessment of vessel response to foraging gray whales along the Oregon coast to promote sustainable ecotourism. 

And finally, Courtney, the most recent Master of Science, and the first graduate of the GEMM Lab will give an oral presentation to round us out on Citizen Science: Benefits and limitations for marine mammal research and education

However, while I am full of excitement and anticipation for the conference, I do regret to report that you will not be seeing a blog post from us next week. That’s because the GEMM Lab recently created a twitter feed and we will be “live tweeting” our conference experience with all of you! You can follow along the conference by searching #Marman15 and follow our Lab at @GemmLabOSU

Twitter is a great way to communicate our research, exchange ideas and network, and can be a great resource for scientific inspiration.

If you are new to twitter, like the GEMM Lab, or are considering pursuing graduate school, take some time to explore the scientific world of tweeting and following. I did and as it turns out there are tons of resources that are aimed for grad students to help other grad students.

For example:

Tweets by the thesis wisperer team (@thesiswisperer) offer advice and useful tips on writing and other grad related stuff. If you are having problems with statistics, there are lots of specialist groups such as R-package related hashtags like #rstats, or you could follow @Rbloggers and @statsforbios to name a few.

As always, thanks for following along, make sure to find us on twitter so you can follow along with the GEMM Labs scientific endeavors.