foraging ecology – Page 6 – Geospatial Ecology of Marine Megafauna Laboratory

A Summer of “Firsts” for Team Whale Storm

By Lisa Hildebrand, MSc student, OSU Department of Fisheries and Wildlife, Geospatial Ecology of Marine Megafauna Lab

To many people, six weeks may seem like a long time. Counting down six weeks until your favourite TV show airs can feel like time dragging on slowly (did anyone else feel that way waiting for Blue Planet II to be released?). Or crossing off the days on your calendar toward that much-needed holiday that is still six weeks away can feel like an eternity. It makes sense that six weeks should feel like a long time. After all, six weeks are approximately a ninth of an entire year. Yet, I can assure you that if you asked anyone on my research team this summer whether six weeks was a long time, they would all say no.

As I watched each of my interns present our research to a room of 50 engaged community members (Fig. 1) after our six week research effort, I couldn’t help but feel an overwhelming sense of pride for all of them at how far they had come during the course of the field season.

Figure 1. Our audience at the community presentation on August 31. Photo by Leigh Torres.

On the very first day of our two-week training back in July, I gave my team an introductory presentation covering gray whales, their ecology, what the next six weeks would look like, how this project had developed and its results to date (Quick side-note here: I want to give a huge shout out to Florence and Leigh as this project would not be what it is today without their hard work and dedication as they laid the groundwork for it three years ago and have continued to improve and expand it). I remember the looks on my interns’ faces and the phrase that comes to mind is ‘deer in headlights’. It isn’t surprising that this was the case as this internship was the first time any of them had done marine mammal field work, or any kind of field work for that matter. It makes me think back to my first taste of field work. I was a fresh high school graduate and volunteering with a bottlenose dolphin research group. I remember feeling out of place and unsure of myself, both in terms of data collection skills but also having to live with the same people I had worked with all day. But as the first few days turned into the first few weeks, I grew into my role and by the end of my time there, I felt like an expert in what I was doing. Based on the confidence with which my interns presented our gray whale foraging ecology research to an audience just over a week ago, I know that they too had become experts in these short six weeks. Experts in levelling a theodolite, in sighting a blow several kilometres out from our cliff site, in kayaking in foggy conditions, in communicating effectively in high stress situations – the list goes on and on.

While you may have read the previous blog posts written by each of my interns in the last four weeks and thus have a sense of who they are, I want to tell you a little more about each of these hardworking undergraduates that played a large role in making this year’s Port Orford gray whale season so effective. Although we did not have any local high school interns this year, the whole team hails from Oregon, specifically from Florence, Sweet Home and Portland.

Figure 2. Haley on the cliff equipped with the camera waiting for a whale to surface. Photo by Cynthia Leonard.

Haley Kent (Fig. 2), my co-captain and Marine Studies Initiative (MSI) intern, an Environmental Science major, is going into her senior year at OSU this fall. She is focused and driven, which I know will enable her to pursue her dream of becoming a shark researcher (I can’t even begin to describe her excitement when we saw the thresher shark on our GoPro video). I couldn’t have asked for a better right hand person for my first year taking over this project and I am excited to see what results she will reveal through her project of individual gray whale foraging preferences. Also, Haley has a big obsession for board games and provided the team with many evenings of entertainment thanks to Munchkin and King of Tokyo.

Figure 3. Dylan in the stern of the kayak on a foggy day reeling down the GoPro stick on the downrigger. Photo by Haley Kent.

Dylan Gregory (Fig. 3) is transferring from Portland Community College and is going to be an OSU junior this fall. Not only was Dylan always extremely helpful in working with me to come up with ways to troubleshoot or fix gear, but his portable speaker and long list of eclectic podcasts always made him a very good cliff team partner. He was also Team Whale Storm’s main chef in the kitchen, and while some of his dishes caused tears & sweat among some team members (Dylan is a big fan of spices), there were never any leftovers, indicating how delicious the food was.

Figure 4. Robyn on one of our day’s off visiting the gigantic Redwoods in California. Photo by Haley Kent.

Robyn Norman (Fig. 4) will be a sophomore at OSU this fall and her commitment to zooplankton identification has been invaluable to the project. Last year when she was a freshman, Robyn was given our zooplankton samples from 2017, a few identification guides and instructions on how to use the dissecting microscope, before she was left to her own devices. Her level of independence and dedication as a freshman was incredible and I am very grateful for the time and skills she has given to this work. Besides this though, Robyn always brought an element of happiness to the room and I can speak on behalf of the rest of the team, that when she was gone for a week on a dive trip, the house did not feel the same without her.

Figure 5. Hayleigh Middleton at the community presentation. Her dry humour and quips earned her a lot of laughter from the audience keeping them entertained. Photo by Tom Calvanese.

Hayleigh Middleton (Fig. 5), a fresh high school graduate and freshly turned 18 during the project, is starting as a freshman at OSU this fall. She is extremely perceptive and would (thankfully) often remind others of tasks that they had forgotten to do (like take the batteries out of the theodolite or to mention the Secchi depth on the GoPro videos). I was very impressed by Hayleigh’s determination to continue working on the kayak despite her propensity for sea sickness (though after a few days we did remedy this by giving her raw ginger to chew on – not her favourite flavour or texture but definitely very, very effective!). She is inquisitive about almost everything and I know she will do very well in her first year at OSU.

Thank you, Team Whale Storm (Fig. 6), for giving me six weeks of your summer and for making my first year as project leader as seamless as it could have been! Without each and every one of you, I would not have been able to survey for 149.2 hours on the cliff, collect over 300 zooplankton samples, identify 31 gray whales, or launch a tandem kayak at 6:30 am every morning.

Figure 6. Team Whale Storm. Back row, from left to right: Haley Kent, Robyn Norman, Hayleigh Middleton, Dylan Gregory. Front row, from left to right: Tom Calvanese, Dr. Leigh Torres, Lisa Hildebrand. Photo by Mike Baran.

My interns were not the only ones to experience many “firsts” during this field season. I learned many new things for the first time right alongside them. While taking leadership is not a foreign concept to me, these six weeks were my first real experience of leading a project and a team for a sustained period of time. Managing teams, delegating tasks and compiling data felt gratifying because I felt like I was exactly where I should be (Fig. 7).

Figure 7. From left to right: Tom, myself, Hayleigh & Dylan on the cliff site looking for whales. Photo by Leigh Torres.

Figure 8. Haley & I on a cold evening out on the water but very excited to have gotten back the GoPro stick retrieved by divers after it had been stuck in a crevice for over 5 days. Photo by Lisa Hildebrand.

I dealt with many daunting tasks, yet thanks to the support of my interns, as well as Tom (Port Orford field station’s incredible station manager), Florence and Leigh, I learned how to resolve my problems: I fixed and replaced broken or lost gear (I am not a very mechanically inclined person; Fig. 8), budgeted food for five hungry people doing tiring field work (I’ve only ever budgeted for one person previously), and taught people how to use gear that I had not often used before (I can say now that the theodolite and I are friends, but this wasn’t the case for the first few weeks…).

Figure 9. Me with all the gear packed into the truck ready to leave Port Orford after the end of the field season. Photo by Haley Kent.

In the lead up to the summer field season this year, Leigh said to me, in one of the many emails we exchanged, that leading the project was a big task but that it was just six weeks long. She suggested that I rest up and get organised as much as I could ahead of time because, after all, the data collected this summer was going to be my thesis data, so I would want it to be as good as possible. Looking back, she couldn’t have been more right – the six weeks simply flew by, I did need the rest she had advised, and it definitely was a big task. I can’t wait for it to happen all over again next summer.

Looking through the scope: A world of small marine bugs

By Robyn Norman, GEMM Lab summer 2018 intern, OSU undergraduate

Although the average human may think all zooplankton are the same, to a whale, not all zooplankton are created equal. Just like us, different whales tend to favor different types of food over others. Thus, creating a meal perfect for each individual preference. Using a plankton net off the side of our kayak, each day we take different samples, hoping to figure out more about prey and what species the whales, we see, like best. These samples are then transported back to the lab for analysis and identification. After almost a year of identifying zooplankton and countless hours of looking through the microscope you would think I would have seen everything these tiny organisms have to offer. Identifying mysid shrimp and other zooplankton to species level can be extremely difficult and time consuming, but equally rewarding. Many zooplankton studies often stop counting at 300 or 400 organisms, however in one very long day in July, I counted over 2,000 individuals. Zooplankton tend to be more difficult to work with due to their small size, fragility, and large quantity.

Figure 1. A sample fresh off the kayak in the beginning stages of identification. Photo by Robyn Norman.

A sample that looks quick and easy can turn into a never-ending search for the smallest of mysids. Most of the mysids that I have sorted can be as small as 5 mm in length. Being difficult to identify is an understatement. Figure 1 shows a sample in the beginning stages of analysis, with a wide range of mysids and other zooplankton. Different species of mysid shrimp generally have the same body shape, structure, size, eyes and everything else you can think of. The only way to easily tell them apart is by their telson, which is a unique structure of their tail. Their telsons cannot be seen with the naked eye and it can also be hard to find with a microscope if you do not know exactly what you are looking for.

Throughout my time identifying these tiny creatures I have found 9 different species of mysid from this gray whale foraging ecology project in Port Orford from the 2017 summer. But in 2018 three mysid species have been particularly abundant, Holmesimysis sculpta, Neomysis rayii, and Neomysis mercedis.

Figure 2. Picture taken with microscope of a *Holmesimysis sculpta* telson. Photo by Robyn Norman.

H. sculpta has a unique telson with about 18 lateral spines that stop as they reach the end of the telson (Figure 2). The end of the telson has 4 large spines that slightly curve to make a fork or scoop-like shape. From my own observations I have also noticed that H. sculpta has darker coloring throughout their bodies and are often heavily pregnant (or at least during the month of August). Neomysis rayii and Neomysis mercedis have been extremely difficult to identify and work with. While N. rayii can grow up to 65 mm, they can also often be the same small size as N. mercedis. The telsons of these two species are very similar, making them too similar to compare and differentiate. However, N. rayii can grow substantially bigger than N. mercedis, making the bigger shrimp easier to identify. Unfortunately, the small N. rayii still give birth to even smaller mysid babies, which can be confused as large N. mercedis. Identifying them in a timely manner is almost impossible. After a long discussion, we decided it would be easier to group these two species of Neomysis together and then sub-group by size. Our three categories were 1-10 mm, 11-15 mm, 16+ mm. According to the literature, N. mercedis are typically 11-15 mm meaning that anything over this size should be a N. rayii (McLaughlin 1980).

Figure 3. Microscopic photo of a gammarid. Photo source: WikiMedia.

Figure 4. Caprellidae found in sample with unique coloration. Photo by Robyn Norman.

While mysids comprise the majority of our samples, they are not the only zooplankton that I see. Amphipods are often caught along with the shrimp. Gammarids look like the terrestrial potato bug and can grow larger than some species of mysid (Fig. 3).

As well as, Caprellidae (Fig. 4) that remind me of little tiny aliens as they have large claws compared to their body size, making it hard to get them out of our plankton net. These impressive creatures are surprisingly hardy and can withstand long times in the freezer or being poked with tweezers under a microscope without dying.

In 2017, there was a high abundance of amphipods found in both of our study sites, Mill Rocks and Tichenor Cove. Mill Rocks surprisingly had 4 times the number of amphipods than Tichenor Cove. This result could be one of the possible reasons gray whales were observed more in Mill Rocks last year. Mill Rocks also has a substantial amount of kelp, a popular place for mysid swarms and amphipods. The occurrence of mysids at each of these sites was almost equal, whereas amphipods were almost exclusively found at Mill Rocks. Mill Rocks also had a higher average number of organisms than Tichenor Cove per samples, potentially creating better feeding grounds for gray whales here in Port Orford.

Analyzing the 2018 data I can already see some differences between the two years. In 2018 the main species of mysid that we are finding in both sites are Neomysis sp. and Holmesimysis sculpta, whereas in 2017 Alienacanthomysis macropsis, a species of mysid identified by their long eye stalks and blunt telson, made up the majority of samples from Tichenor Cove. There has also been a large decrease in amphipods from both locations compared to last year. Two samples from Mill Rocks in 2017 had over 300 amphipods, however this year less than 100 have been counted in total. All these differences in zooplankton prey availability may influence whale behavior and movement patterns. Further data analysis aims to uncover this possibility.

Figure 5. 2017 zooplankton community analysis from Tichenor Cove. There was a higher percentage and abundance of *Neomysis rayii* (yellow) and *Alienacanthomysis macropsis* (orange) than in Mill Rocks.

Figure 6. 2017 zooplankton community analysis from Mill Rocks. There was a higher abundance and percentage of amphipods (blue) and *Holmesimysis sculpta* (brown) than in Tichenor cove. Caprellidae (red) increased during the middle of the season, and decreased substantially towards the end.

The past 6 weeks working as part of the 2018 gray whale foraging ecology research team in Port Orford have been nothing short of amazing. We have seen over 50 whales, identified hundreds of zooplankton, and have spent almost every morning on the water in the kayak. An experience like this is a once in a lifetime opportunity that we were fortunate to be a part of. For the past few years, I have been creating videos to document important and exciting times in my life. I have put together a short video that highlights the amazing things we did every day in Port Orford, as well as the creatures that live just below the surface. I hope you enjoy our Gray Whale Foraging Ecology 2018 video with music by Myd – The Sun.

[B]reaching New Discoveries about Gray Whales in Oregon

By Haley Kent, Marine Studies Initiative (MSI) & summer GEMM Lab intern, OSU senior

“BLOW!”, yells a team “Whale Storm” member, as mist remains above the water from an exhaling gray whale (Eschrichtius robustus). While based at the Port Orford Field Station for 6 weeks of my final summer as an undergrad at Oregon State University my heart has only grown fonder for marine wildlife. I am still in awe of this amazing opportunity of researching the foraging ecology of gray whales as a Marine Studies Initiative and GEMM Lab intern. From this field work I have already learned so much about gray whales and their zooplankton prey, and now it’s time to analyze the data we have collected and see what ecological stories we can uncover.

Figure 1. Robyn and Haley enjoy their time in the research kayak. Photo by Lisa Hildebrand.

WORK IN THE FIELD

This internship is my first field work experience and I have learned many skills and demands needed to study marine wildlife: waking up before the sun (every day begins with screaming alarms), being engulfed by nature (Port Orford is a jaw-dropping location with rich biodiversity), packing up damp gear and equipment to only get my feet wet in the morning ocean waves again, and of course waiting on the weather to cooperate (fog, wind, swell). I wouldn’t want it any other way.

Figure 2. Smokey sunrise from the research kayak. Photo by Haley Kent.

Whether it is standing above the ocean on the ‘Cliff Site’ or sitting in our two-man kayak, every day of this internship has been full of new learning experiences. Using various field work techniques, such as using a theodolite (surveying equipment to track whale location and behavior), Secchi disks (to measure water clarity), GoPro data collection, taking photos of wildlife, and many more tools, have given me a new bank of valuable skills that will stick with me into my future career.

Figure 3. Haley drops Secchi disk from the research kayak. Photo by Dylan Gregory.

Data Analysis

To maximize my amazing internship experience, I am conducting a small data analysis project using the data we have collected these past weeks and in previous summers. There are so many questions that can be asked of these data, but I am particularly interested in how many times individual gray whales return to our study area to forage seasonally or annually, and if these individual whales forage preferentially where certain zooplankton prey are available.

Photo Identification

After many hours of data collection in the field either in the kayak or on the cliff, we get to take a breather in the lab to work on various projects we are each assigned. Some job tasks include processing data, identifying zooplankton, and looking through the photos taken that day to potentially identify a known whale. Once photos are processed and saved onto the rugged laptop, they are ready for some serious one on one. Looking through each of the 300 photos captured each day can be very tedious, but it is worthwhile when a match is found. Within the photos of each individual whale I first determine whether it is the left or right side of the whale – if we are lucky we get both! – and maybe even a fluke (tail) photo!

Figure 4. Buttons’ left side. Photo taken by Gray Whale Team of 2018.

Figure 5. Buttons’ left side. Photo taken by Gray Whale Team of 2017.

The angles of these photos (Fig. 4 & 5) are very different, so it could be difficult to tell these are the same whale. But, have a closer look at the pigmentation patterns on this whale. Focus on a single spot or area of spots, and see how patterns line up. Does that match in the same area in the next photo? If yes, you could have yourself a match!

Buttons, one of the identified gray whales (Fig. 4 & 5), was seen in 2016, 17, and 18. I was so excited to identify Buttons for the 3^rdyear in a row as this result demonstrates this whale’s preference for foraging in Port Orford.

Zooplankton and whale foraging behavior

By using the theodolite we track the whale’s position from the cliff location. I have plugged these coordinates into Google Earth, and compared the coordinates to our zooplankton sample stations from that same day. These methods allow me to assess where the whale spent time, and where it did not, which I can then relate to the zooplankton species and abundance we caught in our sample tows (we use a net from the research kayak to collect samples throughout the water column).

Figure 6. *Holmesimysis sculpta*. This species can range between 4-12mm. The size of this zooplankton relative to the large gray whales foraging on it shows the whale’s incredible senses for prey preference. Photo source: Scripps Institute of Oceanography.

Results (preliminary)

‘Eyeball’ is one of our resident whales that we have identified regularly throughout this season here in Port Orford. I have compared the amount of time Eyeball has spent near zooplankton stations to the prey community we captured at each station.

There is a positive trend in the amount of time the whale spent in an area with the percent abundance of Holmesimysis sculpta (Fig. 7: blue trend line).

Figure 7. Comparative plot between the amount of time the whale “Eyeball” spent within 50m of each zooplankton sampling station and the relative amount of zooplankton species caught at each station. Note the positive trend between time and *Holmesimysis sculpta*, and the negative trend relative to *Neomysis* sp. or Caprellidae.

Conversely, there is an inverse trend with two other zooplankton species: Neomysis sp. (grey trend line) and Caprellidae (orange trend line). These results suggest that Eyeball has a foraging preference for areas where Holmesimysis sculpta (Fig. 6) is more abundant. Who would have known a whale could be so picky? Once the season comes to an end, I plan to use more of our data to continue to make discoveries about the foraging preferences of gray whales in Oregon.

Where the Wild Things Are

By Dylan Gregory, GEMM Lab summer 2018 intern, OSU undergraduate transfer

In ecology, biodiversity is a term often touted for its key importance in stable ecosystems. Every organism plays its role in the constant struggle of nature, competing and cooperating with each other for survival. The sun provides the initial energy to primary producers, herbivores eat those producers, and predators then eat the consumers. The food chain is a simplistic way to look at how ecosystems work, and of course, it is more like an intricate web of interactions. Fungus and plants work together to trade nutrients and create a vast network of fertile soils; kelp forests provide habitats and food for a variety of prey that marine predators feed on. There are checks and balances between all these organisms that give breath into the beauty and color we see in ecosystems around the world. And, here in Port Orford is no exception. Coming to the project I expected to see some whales, of course. However only three weeks in and I’ve been absolutely astounded with the amount of marine biodiversity we’ve experienced. These past three weeks have been nothing if, well, wild.

Eschrichtius robustus, The Gray Whale

There was no doubt we would see gray whales, that is what we are here for after all, and studying them in the field has been an incredibly enlightening experience. Watching an animal every day for weeks really gets you into their head. You start to connect with them and think about their behaviors in different ways. You begin to realize that the individuals have unique quirks, habits and tendencies. For example, one whale would feed quickly for a time, and then seem to run out of energy and “log” itself, floating on the surface, taking multiple breaths in succession to recover before diving back down. Many whales come from the south, to feed in Mill Rocks before moving to Tichenor Cove, and then leave our study region through “Hell’s Gate” to the North, often resting a moment, taking multiple breaths and then launching into the open sea. Still, when you think you know these whales, they surprise you with an alarming unpredictability, making tracking them a new experience every day.

Figure 1 A gray whale surprised us by surfacing right next to our kayak during a routine zooplankton sampling. The site has shown to have a significant amount of zooplankton and it must have been very interested in the prey available, completely ignoring our presence. Photo by Haley Kent.

The whale in Fig. 1 surprised us, and honestly, being so close to it was as humbling as it was awesome. I expected to see whales, but never expected such a close encounter. These gentle giants are one of our not so distant relatives in the ocean. Many of us do this kind of research for more than just the science and the data. Many of us do it for the connection we feel to our mammal family.

Phoca vitulina richardii, The Pacific Harbor Seal

I absolutely adore these harbor seals! They’re well known for their friendliness towards humans as their dopey little heads pop up out of the water to greet you with a curious look in their eyes. They like to bob in the surf and stare at us while we’re out sampling in the kayak. At first, we got quite excited seeing one, often startling them as we’d squeal “seal!” to each other and they’d dip back under and scurry away. Now though, they seem more comfortable being around our kayak (Fig. 2).

Figure 2 This harbor seal surfaced next to Haley and me shortly before the whale in Fig 1. We named him Courage, as he stuck around and kept us company during the whole encounter. Photo by Haley Kent.

One day a seal followed Lisa and Hayleigh around the jetty on their way back from sampling, swimming around the kayak and investigating them. Out in Mill Rocks, we often see them stretching on top of the rocks, seemingly doing a little yoga session while basking in the morning sun. Despite their cute and cuddly appearance, they are still predators. With plenty of fish to eat and make them happy, these harbor seals are quite plentiful themselves, and I’d like to think we’ve become quite good friends with the little guys.

Tursiops truncatus, The Bottlenose Dolphin

Figure 3 A shot of the dorsal fin seen on August 9th in Mill Rocks. Photo by Dylan Gregory.

One morning we were in Mill Rocks and a large cloud of fog moved in, so we decided to wait it out before making our passage to Tichenor Cove. While sitting there, enjoying a snack, we noticed some dorsal fins popping up about 100 meters from us. Caught by surprise, Haley and I scrambled for our cameras and lo and behold, we noticed they were a small pod of dolphins! Two adults and a calf. Unfortunately, as you can see from our pictures, it is difficult to identify what species they were exactly.

Figure 4 The head and rostrum of the dolphin seen in Mill Rocks on August 9th. Photo by Dylan Gregory.

After communicating with Lisa and Leigh, we have decided that their dorsal fins were far too big and curved to be harbor porpoises (Fig. 3), and the intersection of the head and rostrum seem to have the classic look of a bottlenose dolphin (Fig. 4).

If these were in fact bottlenose dolphins, why are they here in Port Orford, Oregon? It’s uncommon for them to be so far north in our colder waters. Were they foraging for food? Finding refuge from predators? Is it because our waters are becoming warmer? A sighting like this gives more weight to how climate change is affecting our oceans and how marine animals are responding by adapting their migratory and feeding behaviors.

Pisaster and Pycnopodia, The Common Sea Star and the Sunflower Star

Figure 5 Pisaster sea stars and anemones on a rock in Mill Rocks. No Pycnopodia (often called sunflower stars for their many legs) have been spotted in our study zone. Photo by Haley Kent.

One of the coolest aspects of living at the Port Orford Field Station is the fact that we have access to a lot of engagement with other scientists. For instance, we were able to attend a webinar about Sea Star Wasting Disease (SSWD) research currently happening at OSU by Post Doc Sarah Gravem. In a nutshell, a bacterial disease has been infecting sea stars along the west coast, causing a rapid plummet in their populations. Pisaster and Pycnopodia (Fig. 5) have been particularly affected. They are keystone predators, and as such, hold an important role in intertidal ecosystems. Feeding on snails, urchins, other sea stars and various mollusks, these sea stars maintain species populations and allow for a diverse and stable intertidal zone, which then supports many other near shore marine species. While SSWD’s cause is relatively unknown, Pisaster seems to be recovering while Pycnopodia is still struggling. I’ve even heard some anecdotal reports that fishermen here in Port Orford have noticed the lack of Pycnopodia as well, but they are rather pleased that these “ragmops” have stopped mucking up their lines and crab pots.

Below the Surface

There is a charm to the deep, a mystery and wonder that has captured the imagination of humans ad nauseam. Stories, movies, music and masterpieces of art have been inspired by The Abyss. Below the surface lies a diverse world teeming with life, full of questions and answers to be found. While marine mammals are why we’re here, there’s an entirely different environment under the water that is unseen from the safety of our dry, oxygen rich air. Our research doesn’t involve any diving, and so our eyes under the water are a GoPro camera attached to a downrigger on our kayak. Although designed to measure zooplankton community density, we’ve seen quite a bit more than itty bitty sea bugs in the depths of our little harbor here in Port Orford.

Strongylocentrotus purpuratus, The Purple Sea Urchin

Urchins are known for their bright colors and spiny ball like exterior. Close relatives to the sea stars, urchins inhabit the intertidal zones and also take residence within kelp beds. During our kayak training, we passed by some rocks near the cliffs and it was an awesome sight seeing the diversity of intertidal critters such as anemones, sea stars and sea urchins. However, a week into data collection, we have noticed something startling: a large quantity of the urchins cover the seafloor and the kelp, or at least what was left of the kelp (Fig. 6).

Figure 6 Sea Urchins decimating a kelp bed in Tichenor Cove. Photo captured from GoPro footage.

Sea urchins are important members in their communities. They graze on algae and control it from overwhelming the waters, but when left unchecked urchins can completely decimate kelp beds. This pattern is often referred to as “urchin barrens”. Sea otters and sea stars are the urchin’s main predator, and due to the absence of otters and the emergence of SSWD, the occurrence of urchin barrens has risen. An assessment of the reintroduction of the sea otters to Oregon by Dominique Kone, a GEMM Lab graduate student, is underway, and there is a lot of new research on SSWD, both of which could support the ‘ecosystem control’ of urchin populations. We’ve already spotted the urchins wreaking their havoc on the kelp in two separate sites in Tichenor Cove. Since gray whales primarily feed within these kelp beds, this increase in urchin populations is something that we are monitoring. An urchin barren can happen quickly and causes significant ecosystem damage, so this is not something to ignore. If we lose the kelp, it’s easy to imagine that we may lose the whales.

Alopias vulpinus, The Thresher Shark

Figure 7 A thresher shark spotted in Tichenor Cove in Port Orford, OR. Photo captured by GoPro footage.

By far, the most exciting thing I’ve seen so far has been this lovely creature (Fig. 7). The thresher shark usually inhabits the oceanic and coastal zones in tropical and temperate waters. They feed on pelagic schooling fish, squid and sometimes even shorebirds. They attack by whipping their tails (which grow to be the size of their body!) at their prey to stun them. Threshers are on the IUCN Red List of Threatened Species as “Vulnerable” due to their declining populations. They are often hunted for shark fin soup, or by trophy hunters due to their elegant and unique tails.

Haley, our resident shark enthusiast, was able to tell that this shark was a female by the lack of claspers (male appendages) on her pelvic fin. Why was she here though? During the summer, threshers will migrate to colder yet productive northern waters to feed, and on some rare occasions, such as this one, they will come closer to shore. Perhaps she was chasing prey into the harbor and found it to be full of yummy food, or she is a juvenile, which often stay near the continental shelf.

Either way, we were all surprised and excited to see such an exotic and beautiful species of shark caught on camera in our study zone. She even does a little strut in front of the GoPro camera, showing off her beautiful caudal fin!

Protecting our Wilds

These are only a few examples of the many different animals at work in Port Orford’s ecosystem. Perhaps the biodiversity here is why this is such a hot spot for our whale friends. The productive and lively waters have shown us so many critters, and likely many more we have yet to see. But alas, we have three more weeks of data collection and new discoveries, and I couldn’t be more excited.

“It is a curious situation that the sea, from which life first arose should now be threatened by the activities of one form of that life. But the sea, though changed in a sinister way, will continue to exist; the threat is rather to life itself.”

– Rachel Carson, The Sea Around Us

This experience only drives me further into my pursuit of ecological research. I believe it’s incredibly important to understand the world and how it functions, and to do so before it’s too late. All too often we have breakthrough discoveries in science because something has already fallen apart. Ecosystems are fragile, and climate change, pollution, and other anthropogenic disturbances all have an impact which damage and alter ecosystems and the services they provide. However, it’s an impact we can control with a fundamental understanding of how nature works. With a little hope, some integrity, and a whole lot of passion, I believe we have the power to truly make a difference.

Cold Fingers and Carabiners

By Hayleigh Middleton, GEMM Lab summer 2018 intern, entering OSU undergrad

Cold Fingers and Carabiners: that’s what most of the past three weeks have been about. We’ve progressively been getting up earlier—with many thanks to the coffee pot and multiple alarms— in order to be on the water collecting data before the wind and fog decide to kick in. Working on the ocean at 7 am with wet hands, metal equipment, a tight suit, and a “refreshing” breeze while trying to keep an eight-foot sit-on-top kayak from tipping over is challenging to say the least. Making sure the Theodolite is perfectly level on its tripod resting on sand-covered ground at the top of a cliff? Not much easier. The air is cold, the wind is cold, the equipment is cold, I’m cold, and now, everything is wet.

Rugged laptop on the cliff site. Photo by Hayleigh Middleton.

I absolutely love it.

Of all the ways I could have chosen to spend my summer before starting college at OSU, I’m so glad I took a chance and asked to spend it here. The official goals of our research project are to monitor and record the foraging habits of the Pacific Coast Feeding Group of gray whales, attempt to find out if specific individuals tend to have site fidelity and forage here year after year, and why or how they choose certain spots to feed over others. What does that mean for me? I get to kayak and take pictures of whales for six weeks! Of course, there’s a bunch of technical stuff and expensive equipment that took us two weeks to learn, but now we’re off to a great start and ready to learn more about these amazing creatures.

We have such a short amount of time to collect all this data to try and fill in the puzzle that is gray whale behavior, and we’re only a few weeks in, but I feel like I’ve already connected with this group of 60,000-pound mammals. That, in essence, is really what we’re doing here. We’re on top of a 33-meter-high cliff watching empty water for hours on the chance that we’ll be able to see a whale, identify it through photo-ID, track it with the theodolite to figure out its behavior, and use our kayak data to figure out its diet and feeding choices. Even though the whales forage up to two kilometers away from our tracking spot, it feels like they know we’re watching them. Sometimes it feels like they’re teasing us—we’ll see one, and once we get the sights fixed on it, it dives down and doesn’t come back up until we’ve turned our attention. One whale got into a very predictable pattern: three blows and then a deep dive, forage for five minutes, pop up half a viewfinder away, three more blows. We set our sights on the third blow and waited for her to resurface.

…and waited.

She swam away and didn’t show herself again.

Other times it’s like they conspire against us. Earlier this week, we spent most of the morning tracking the same whale. A couple hours into the track, another whale popped up right next to the first. Since we use a computerized tracking program, each whale is assigned a group number. That way, we can track each individual’s path and later match it to the photo identification database and sometimes a nickname. The two whales surfaced at just the right frequency and distance apart that deciding which number was currently up was guesswork for a good 15 minutes, but we gave them new track numbers and were able to sort it out later after reviewing our photos.

Searching for whales. Photo by Haley Kent.

On another day, we surveyed for whales until quitting time, which is 3:00 pm. About 2:30 pm, one was finally spotted. I named her Princess because she couldn’t be bothered to bring her body out of the water enough so we could mark her location or take a picture except for when her pectoral fin, the tip of which was “gloved” in white, came out and made a motion like a princess in a parade. When there are whales around, we can’t just say “oh look, 3:00 pm time to go” because this is important data to collect. So, we decided to wait until 3:30 pm to see if she surfaced again within visual range. 3:30 pm came and still no sign of her, so I packed up the theodolite and tripod. As soon as the box was closed, she blew, and another whale surfaced right in front of the cliff. We got some pictures of the closer one for a bit and decided that was enough. As the camera was being lowered into its case, another whale surfaced in the cove. It felt like the first went and told all the whales heading south “hey, these guys want to leave at 3, so show up right around then.” That day we got back to the lab around 5. Even though this meant being on the cliff for almost 10 hours that day, it was thrilling to have seen so many whales in one day.

Then there are times when the whales seem to beg for attention. On our third day on the cliff, we saw what we believe to be a juvenile come swimming into view. We assume that he was a juvenile because he was “small” and quite blank in terms of pigmentation and scarring. He was adorable. He stayed over at Mill Rocks for a while foraging, all of which we “fixed” into the tracking program via the Theodolite, and then he came toward us into the little kelp patch just in front of our cliff site. He would dive down, scoop up some zooplankton to eat, and resurface right in the middle of the kelp. The cutest part is that he would then proceed to roll around in the kelp and further drape himself in it.

Having such a young whale come and forage made us wonder if mothers who have site fidelity then teach their young “hey, you don’t have to go all the way north, there’s a ton of good food here in Port Orford.” Hopefully that’s one of the things we’ll be able to figure out with the data collected with this long–term study. But in the meantime, I still have three weeks of data to collect and a bunch more whales to meet.

Cloudy with a chance of blue whales

By Dawn Barlow, PhD student, Department of Fisheries & Wildlife, Geospatial Ecology of Marine Megafauna Lab

As a PhD student studying the ecology of blue whales in New Zealand, my time is occupied by questions such as: When and where are the blue whales? Can we predict where they will be based on environmental conditions? How does their distribution overlap with human activity such as oil and gas exploration?

Leigh and I have just returned from New Zealand, where I gave an oral presentation at the Society for Conservation Biology Oceania Congress entitled “Cloudy with a chance of whales: Forecasting blue whale presence to mitigate industrial impacts based on tiered, bottom-up models”. While the findings I presented are preliminary, an exciting ecological story is emerging, and one with clear management implications.

The South Taranaki Bight (STB) region of New Zealand is an important area for a population of blue whales which are unique to New Zealand. A wind-driven upwelling system brings cold, productive waters into the bight [1], which sustains high densities of krill [2], blue whale prey. The region is also frequented by busy shipping traffic, oil and gas drilling and extraction platforms as well as seismic survey effort for subsurface oil and gas reserves, and is the site of a recently-permitted seabed mine for iron sands (Fig. 1). However, a lack of knowledge on blue whale distribution and habitat use patterns has impeded effective management of these potential anthropogenic threats.

Figure 1. A blue whale surfaces in front of a floating production storage and offloading vessel servicing the oil rigs in the South Taranaki Bight. Photo by D. Barlow.

Three surveys were conducted in the STB region in the summer months of 2014, 2016, and 2017. During that time, we not only looked for blue whales, we also collected oceanographic data and hydroacoustic backscatter data to map and measure aspects of the krill in the region. These data streams will help us understand the functional, ecological relationships between the environment (oceanography), prey (krill), and predators (blue whales) in the ecosystem (Fig. 2). But in practice these data are costly and time-consuming to collect, while other data sources such as satellite imagery are readily accessible to managers at a variety of spatial and temporal scales. Therefore, another one of my aims is to link the data we collected in the field to satellite imagery, so that managers can have a practical tool to predict when and where the blue whales are most likely to be found in the region.

Figure 2. Data streams collected during surveys of the South Taranaki Bight Region in 2014, 2016, and 2017.

So what did I find? Here are the highlights from my preliminary analyses:

The majority of the patterns in blue whale distribution can be explained by the density, depth, and thickness of the krill patches.
Patterns in the krill are driven by oceanography.
Those same oceanographic parameters that drive the krill can be used to explain blue whale distribution.
There are tight relationships between the important oceanographic variables and satellite images of sea surface temperature.
Blue whale distribution can, to some degree, be explained using just satellite imagery.

We were able to identify a sea surface temperature range in the satellite imagery of approximately 18°C where the likelihood of finding a blue whale is the highest. Is this because blue whales really like 18° water? Well, more likely this relationship exists because the satellite imagery is reflective of the oceanography, and the oceanography drives patterns in the krill distribution, and the krill drives the distribution of blue whales (Fig. 3). We were able to make each of these functional linkages through our series of models, which is quite exciting.

Figure 3. The tiered modeling approach we took to investigate the ecological relationships between blue whales, krill, oceanography, and satellite imagery. Because of the ecological linkages we made, we are able to say that any relationship between whale distribution and satellite imagery most likely reflects a relationship between the blue whales and their prey.

That’s all well and good, but we were interested in testing these relationships to see if our identified habitat associations hold up even when we do not have field data (oceanographic, krill, and whale data). This past austral summer, we did not have a field season to collect data, but there was a large seismic airgun survey of the STB region. Seismic survey vessels are required to have trained marine mammal observers on board, and we were given access to the blue whale sightings data they recorded during the survey. In December, when the water was right around the preferred temperature identified by our models (18°C), the observers made 52 blue whale sightings (Fig. 4). In January and February, the waters warmed and only two sightings were made in each month. This is not only reassuring because it supports our model results, it also implies that there is the potential to balance industrial use of the area with protection of blue whale habitat, based on our understanding of the ecology. In January and February, very few blue whales were likely disturbed by the industrial activity in the STB, as conditions were not favorable for foraging at the location of the seismic survey. In contrast, the blue whales that were in the STB region in December may have experienced physiological consequences of sustained exposure to airgun noise since the conditions were favorable for foraging in the STB. In other words, the whales may have tolerated the noise exposure to gain access to good food, but this could have significant biological repercussions such as increased stress [3].

Figure 4. Monthly sea surface temperature (MODIS Aqua) overlaid with blue whale sightings from marine mammal observers aboard seismic survey vessel R/V Amazon Warrior. Black rectangles represent areas of seismic survey effort. Blue whale sighting location data were provided by RPS Energy Pty Ltd & Schlumberger, and Todd Energy.

In the first two weeks of July, we presented these latest findings to managers at the New Zealand Department of Conservation, the Minister of Conservation, the CEO and Policy Advisor of a major oil and gas conglomerate, NGOs, advocacy groups, and scientific colleagues. It was valuable to gather feedback from many different stakeholders, and satisfying to see such a clear interest in, and management application of, our work.

Dr. Leigh Torres and Dawn Barlow in front of Parliament in Wellington, New Zealand, following the presentation of their recent findings.

What’s next? We’re back in Oregon, and diving back into analysis. We intend to take the modeling work a step further to make the models predictive—for example, can we forecast where the blue whales will be based on the temperature, productivity, and winds two weeks prior? I am excited to see where these next steps lead!

References:

Shirtcliffe TGL, Moore MI, Cole AG, Viner AB, Baldwin R, Chapman B. 1990 Dynamics of the Cape Farewell upwelling plume, New Zealand. New Zeal. J. Mar. Freshw. Res. 24, 555–568. (doi:10.1080/00288330.1990.9516446)
Bradford-Grieve JM, Murdoch RC, Chapman BE. 1993 Composition of macrozooplankton assemblages associated with the formation and decay of pulses within an upwelling plume in greater cook strait, New Zealand. New Zeal. J. Mar. Freshw. Res. 27, 1–22. (doi:10.1080/00288330.1993.9516541)
Rolland RM, Parks SE, Hunt KE, Castellote M, Corkeron PJ, Nowacek DP, Wasser SK, Kraus SD. 2012 Evidence that ship noise increases stress in right whales. Proc. Biol. Sci. 279, 2363–8. (doi:10.1098/rspb.2011.2429)

Oregon sea otter reintroduction: opinions, perspectives, and theories

By Dominique Kone, Masters Student in Marine Resource Management

Species reintroductions can be hotly contested issues because they can negatively impact other species, ecosystems, and society, as well as failing, altogether. The uncertainty of their outcomes forces stakeholder groups to form their own opinions on whether it’s a good idea to proceed with a reintroduction. When you have several groups with conflicting values and views, managers need to focus on the information most important for them to make a well-informed decision on whether to pursue a reintroduction.

As researchers, we can play an important role by carefully considering and addressing these views through our research, if the appropriate data is available. Despite being in the early days of our study on the potential sea otter reintroduction to Oregon, we have already heard several perspectives regarding its potential success, the type of research we should do, and if sea otters should be brought back to Oregon. Here, I present some of the most interesting and relevant opinions, perspectives, and theories I’ve heard regarding this reintroduction idea.

The first reintroduction failed because of X, Y, and Z.

From 1970-1971, managers translocated 93 sea otters to Oregon in a reintroduction effort (Jameson et al. 1982). However, in a matter of 5-6 years, all sea otters disappeared, and the effort was considered a failure. Researchers have theorized that sea otters left Oregon due to a lack of suitable habitat and prey, or to return home to sites from which they were captured. Others have reasoned that managers should have introduced southern sea otters instead of northern sea otters, suggesting one subspecies’ genetic pre-disposition may improve their chance for survival.

Knowing the reasons for this failure may help managers avoid these causes in a future reintroduction attempt and increase its chance of success. We, as scientists, can also gain insight from knowing these causes because this may help us better tailor our research to potentially investigate whether those causes still pose a threat to sea otters during a second attempt. Unfortunately, we lack concrete evidence on what exactly caused this failure, but we can still work to test some these theories.

An otter is an otter, no matter where you put it.

There is evidence that northern and southern sea otters are genetically distinct, to a certain degree (Valentine et al. 2008, Larson et al. 2012), and hypotheses have been put forward that the two subspecies may be behaviorally- and ecologically-distinct, too. Studies have shown that northern and southern sea otters have different sized and shaped skulls and teeth, which researchers hypothesize may be a specialized foraging adaptation for consuming different prey species (Campbell & Santana 2017, Timm-Davis et al. 2015). This view suggests that each subspecies has developed unique traits to adapt to the environmental conditions specific to their current ranges. Therefore, when considering which subspecies to bring to Oregon, managers should reintroduce the subspecies with traits better-suited to cope with the types of habitat, prey assemblages, and oceanographic conditions specific to Oregon.

However, other scientists hold the opposite view, and argue that “an otter is an otter” no matter where you put it. This perspective suggests that both subspecies have an equal chance at surviving in any type of suitable habitat because all otters behave in similar ways. Therefore, ecologically, it may not matter which subspecies managers bring to Oregon.

Oregon doesn’t have enough sea otter habitat.

Kelp is considered important sea otter habitat. In areas with high sea otter densities, such as central and southern California, kelp forests are persistent throughout the year. However, in Oregon, our kelp primarily consists of bull kelp – a slightly more fragile species compared to the durable giant kelp in California. In winter, this bull kelp gets dislodged during intense storms, resulting in seasonal changes in kelp availability. Managers worry that this seasonality could reduce the amount of suitable habitat, to the point where Oregon may not be able to support sea otters.

Yet, we know sea otters used to exist here; therefore, we can assume there must have been some suitable habitat that may persist today. Furthermore, sea otters use a range of habitats, including estuaries, bays, and reefs (Laidre et al. 2009, Lafferty & Tinker 2014, Kvitek et al. 1988). Therefore, even during times when kelp is less abundant, sea otters could use these other forms of habitat along the Oregon coast. Luckily, we have the spatial tools and data to assess how much, where, and when we have suitable habitat, and I will specifically address this in my thesis.

They’ll eat everything!

Sea otters are famous for their voracious appetites for benthic invertebrates, some of which are of commercial and recreational importance to nearshore fisheries. In some cases, sea otters have significantly reduced prey densities, such as sea urchins and Dungeness crab (Garshelis & Garshelis 1984, Estes & Palmisano 1974). However, without a formal analysis, it’s difficult to know if sea otters will have similar impacts on Oregon’s nearshore species, as well as at spatial scale these impacts will occur and whether our fisheries will be affected. We can predict where sea otters are likely to occur based on the presence of suitable habitat, but foraging impacts could be more localized or widespread across sea otter’s entire potential range. To better anticipate these impacts, managers will need an understanding of how much sea otters eat, where foraging could occur based on the availability of prey, and where sea otters and fisheries are likely to interact. I will also address this concern in my thesis.

To reintroduce or not to reintroduce? That is the question.

I have found that many scientists and managers have strong opinions on whether it’s appropriate to bring sea otters back to Oregon. Those who argue against a reintroduction often highlight many of the theories already mentioned here – lack of habitat, potential impacts to fisheries, and genetics. While other opponents provided more logistical and practical justifications, such as confounding politics, as well as difficulties in getting public support and regulatory permission to move a federally-listed species.

In contrast, proponents of this idea argue that a reintroduction could augment the recovery of the species by providing additional habitat for the species to rebound to pre-exploitation levels, as well as allowing for increased gene flow between southern and northern sea otter populations. Other proponents have brought up potential benefits to humans, such restoring ecosystem services, providing an economic boost through tourism, or preserving tribal and cultural connections. Such benefits may be worth attempting another reintroduction effort.

As you can see, there are several opinions and perspectives related to a potential sea otter reintroduction to Oregon. While it’s important to consider all opinions, managers still need facts to make key decisions. Scientists can play an important role in providing this information, so managers can make a well-informed decision. Oregon managers have not yet decided whether to proceed with a sea otter reintroduction, but our lab is working to provide them with reliable and accurate science, so they may form their own opinions and arrive at their own decision.

References:

Estes, J. A. and J. F. Palmisano. 1974. Sea otters: the role in structuring nearshore communities. Science. 185: 1058-1060.

Garshelis, D. L. and J. A. Garshelis. 1984. Movements and management of sea otters in Alaska. The Journal of Wildlife Management. 48: 665-678.

Jameson, R. J, Kenyon, K. W., Johnson, A. M., and H. M. Wight. 1982. History and status of translocated sea otter populations in North America. Wildlife Society Bulletin. 10: 100-107.

Lafferty, K. D., and M. T. Tinker. 2014. Sea otters are recolonizing southern California in fits and starts. Ecosphere. 5(5).

Laidre, K. L., Jameson, R. J., Gurarie, E., Jeffries, S. J., and H. Allen. 2009. Spatial habitat use patterns of sea otters in coastal Washington. Journal of Mammalogy. 90(4): 906-917.

Kvitek, R. G. ,Fukayama, A. K., Anderson, B. S., and B. K. Grimm. 1988. Sea otter foraging on deep-burrowing bivalves in a California coastal lagoon. Marine Biology. 98: 157-167.

Larson, S., Jameson, R., Etnier, M., Jones, T., and R. Hall. 2012. Genetic diversity and population parameters of sea otters, Enhydra lutris, before fur trade extirpation from 1741-1911. PLoS ONE. 7(3).

Timm-Davis, L. L, DeWitt, T. J., and C. D. Marshall. 2015. Divergent skull morphology supports two trophic specializations in otters (Lutrinae). PLoS ONE. 10(12).

Valentine et al. 2008. Ancient DNA reveals genotypic relationships among Oregon populations of the sea otter (Enhydra lutris). Conservation Genetics. 9:933-938.

Assessing suitable sea otter habitat along Oregon’s coast

By Dominique Kone, Masters Student in Marine Resource Management

When considering a species reintroduction into an area, it is important to assess the suitability of the area’s habitat before such efforts begin. By doing this assessment at the outset, managers and conservationists can gain a better understanding of the capacity of the area to support a viable population overtime, and ultimately the success of the reintroduction. However, to do a habitat assessment, researchers must first have a base understanding of the species’ ecological characteristics, behavior, and the physical habitat features necessary for the species’ survival. For my thesis, I plan to conduct a similar assessment to identify suitable sea otter habitat to inform a potential sea otter reintroduction to the Oregon coast.

To start my assessment, I conducted a literature review of studies that observed and recorded the various types of habitats where sea otters currently exist. In my research, I learned that sea otters use in a range of environments, each with a unique set of habitat characteristics. With so many features to sort through, I have focused on specific habitat features that are consistent across most of the current range of sea otters – from Alaska to California – and are important for at least some aspects of sea otters’ everyday life or behavior, specifically foraging. Focusing my analysis on foraging habitat makes sense as sea otters require around 30% of their body weight in food every day (Costa 1978, Reidman & Estes 1990). Meaning sea otters spend most of their day searching for food.

Here, I present four habitat features I will incorporate into my analysis and explain why these features are important for sea otter foraging behavior and survival.

Habitat Features:

Kelp: Sea otters are famously known for the benefits they provide to kelp forests. In the classic three-trophic-level model, sea otters allow for the growth of kelp by keeping sea urchins – consumers of kelp – in check (Estes & Palmisano 1974). Additionally, sea otters and kelp have a mutually-beneficial relationship. Sea otters will often wrap themselves amongst the top of kelp stocks while feeding, resting, or grooming to prevent being carried away by surface currents. Meanwhile, it’s thought that kelp provide a refuge for sea otters seeking to avoid predators, such as sharks, as well as their prey.

Distance from Kelp: The use of kelp, by sea otters, is relatively straight-forward. Yet, kelp can still have an influence on sea otter behavior even when not used directly. A 2014 study found that sea otters along the southern California coast were almost 10 times more likely to be located within kelp habitat than outside, while outside kelp beds sea otter numbers declined with distance from the edge of kelp canopies. Sea otters will often forage outside or next to kelp canopies when prey’s available, and even sometimes to socialize in age- or sex-specific rafts (Lafferty & Tinker 2014). These findings indicate that sea otters can and do regularly disperse away from kelp habitat, but because they’re so dependent on kelp, they don’t stray very far.

Seafloor Substrate: Sea otters forage over a variety of sediment substrates, including rocks, gravel, seagrass, and even sometimes sand. For example, sea otters hunt sea urchins over rocky substrates, while in other areas they may hunt for crabs in seagrass beds (Estes & Palmisano 1974, Hughes et al. 2014). The type of substrate sea otters forage in typically depends on the substrate needs of their target prey species. Despite some variability across their range, sea otters predominantly forage in rocky substrate environments. Rocky substrate is also necessary for kelp, whose holdfasts need to attach to hard, stable surfaces (Carney et al. 2005).

Depth: Seafloor depth plays a pivotal role in sea otter foraging behavior and therefore acts as a natural boundary that determines how far away from shore sea otters distribute. Many of the prey species sea otters eat – including sea urchins, crabs, and snails – live on the seafloor of the inner continental shelf, requiring sea otters to dive when foraging. Interestingly, sea otters exhibit a non-linear relationship with depth, where most individuals forage at intermediate depths as opposed to extremely shallow or deep waters. One study found the average foraging depth to be around 15 meters (Lafferty & Tinker 2014). This behavior results in a hump-shaped distribution of diving patterns as illustrated in Figure 1 below.

Figure 1. Average probability of occurrence as a function of depth for female (A) and male (B) sea otters as predicted by a synoptic model of space-use (Tinker et al. 2017).

Of course, local conditions and available habitat are always a factor. For example, a study found that sea otters along the coast of Washington foraged further from shore and in slightly shallower environments than sea otters in California (Laidre et al. 2009), indicating that local topography is important in determining distribution. Additionally, diving requires energy and limits how deep sea otters are able to forage for prey. Therefore, diving patterns are not only a function of local topography, but also availability of prey and foraging efficiency in exploiting that prey. Regardless, most sea otter populations follow this hump-shaped diving pattern.

These features are not a complete list of all habitat characteristics that support viable sea otter populations, but seem to be the most consistent throughout their entire range, as well as present in Oregon’s nearshore environment – making them ideal features to include in my analysis. Furthermore, other studies that have predicted suitable sea otter habitat (Tinker et al. 2017), estimated carrying capacity as a product of suitable habitat identification (Laidre et al. 2002), or simply observed sea otter foraging behavior (Estes & Palmisano 1974), have echoed the importance of these four habitat features to sea otter survival.

As with most reintroduction efforts, the process of identifying suitable habitat for the species of interest can be complicated. No two ecosystems or habitats are exactly alike and each comprise their own unique set of physical features and are impacted by environmental processes to varying degrees. The Oregon coast consists of a unique combination of oceanographic conditions and drivers that likely impact the degree and amount of available habitat to sea otters. Despite this, by focusing on the habitat features that are consistently preferred by sea otters across most of their range, I will be able to identify habitat most suitable for sea otter survival in Oregon. The questions of where this habitat is and how much is available are what I’ll determine soon, so stay tuned.

References:

Carney, L. T., Robert Waaland, J., Kilinger, T., and K. Ewing. 2005. Restoration of the bull kelp Nereocystis luetkeana in nearshore rocky habitats. Marine Ecology Progress Series. 302: 49-61.

Costas, D. P. 1978. The ecological energetics, waters, and electrolyte balance of the California sea otter (Enhydra lutris). Ph.D. dissertation, University of California, Santa Cruz.

Estes, J. A. and J. F. Palmisano. 1974. Sea otters: their role in structuring nearshore communities. Science. 185(4156): 1058-1060.

Hughes et al. 2014. Recovery of a top predator mediate negative eutrophic effects on seagrass. Proceedings of the National Academy of Sciences. 110(38): 15313-15318.

Lafferty, K. D. and M. T. Tinker. 2014. Sea otters are recolonizing southern California in fits and starts. Ecosphere. 5(5): 1-11.

Laidre et al. 2002. Estimates of carrying capacity for sea otters in Washington state. Wildlife Society Bulletin. 30(4): 1172-1181.

Laidre et al. 2009. Spatial habitat use patterns of sea otters in coastal Washington. Journal of Mammalogy. 90(4): 906-917.

Tinker et al. 2017. Southern sea otter range expansion and habitat use in the Santa Barbara Channel, California: U.S. Geological Survey Open-File Report 2017-1001 (OCS Study BOEM 2017-022), 76 p., http://doi.org/10.3133/ofr20171001.

Reidman, M. L. and J. A. Estes. 1990. The sea otter (Enhydra lutris): behavior, ecology, and natural history. United States Department of the Interior, Fish and Wildlife Service, Biological Report. 90: 1-126.

With new approaches come new insights: What we do and don’t know about blue whales

By Dawn Barlow, MSc student, Department of Fisheries and Wildlife

A few weeks ago, my labmate Dom’s blog reminded me that it is important to step back from the data and appreciate the magnificence of the animals we study from time to time. I have the privilege of studying the largest creatures on the planet. When people hear that I study blue whales, I often get a series of questions: Just how big are they, really? How many are there? Where do they migrate? Where do they breed? Despite the fact that humans hunted blue whales nearly to extinction [1,2], we still know next to nothing about these giants. The short answer to many of those questions is, “Well we don’t really know, but we’re working on it!” Which brings me back to taking time to marvel at these animals for a bit. Isn’t it remarkable that the largest animals on earth can be so mysterious?

A blue whale comes up for air in a calm sea. Photo by Leigh Torres.

Last year at this time we were aboard a research vessel in New Zealand surveying for blue whales and collecting a myriad of biological data to try and glean some insight into their lives. This winter I am processing those data and conducting a literature review to get a firm grasp on what others have found before about blue whale foraging and bioenergetics. On any given Tuesday morning Leigh and I can be found musing about the mechanics of a baleen whale jaw, about what oceanographic boundaries in the water column might be meaningful to a blue whale, about how we might quantify the energy expenditure of a foraging whale. Here are some of those musings.

Approaching a blue whale in a rigid-hull inflatable boat for data collection. UAS piloted by Todd Chandler.

Humans are, for the most part, terrestrial creatures. Even those of us that would prefer to spend most of our time near, on, or in the water are limited in what we can observe of marine life. Much of the early data that was collected on blue whales came from whaling catches. Observations of anatomy and morphology were made once the whales were killed and taken out of their marine environment. This was not long ago—Soviet whaling continued into the 1970’s in New Zealand [3]. Because baleen whales are long lived (exact age unknown for blue whales but a bowhead whale was estimated to be at least 150 years old [4]) it is entirely possible that blue whales living today remember being hunted by whalers. Observing whales in their natural state is not easy, particularly post-commercial whaling when they are few and far between.

Yet, where there is a challenge, clever people develop creative approaches and new technologies, leading to new insights. High-quality cameras have allowed scientists to photograph whales for individual identification—a valuable first step in figuring out how many there are and where they go [5]. Satellite tags have allowed scientists to track the movement of blue whales in the North Pacific and Indian Oceans, a first step in learning where these whales might go to breed. However, no blue whale breeding ground has definitively been discovered yet…

What does a whale do when it is below the surface, out of sight of our terrestrial eyes? A study from 1986 that attempted to calculate the prey demands of a whale assumed that whenever a whale was submerged, it was feeding [6]. A big assumption, but a starting place without any dive data. By 2002, tags equipped with time-depth recorders (TDR) had already revealed that blue whales make dives of variable depths and shapes [7]. But, what determines a whale’s path underwater, where they must conserve as much oxygen as they can while finding and exploiting patches of prey? The advent of digital acoustic recording tags (DTAGs) in the early 2000s have allowed scientists to measure the fine-scale movements of whales in three dimensions [8]. These tags can capture the kinematic signatures (based on pitch, roll, and yaw) of lunge-feeding events below the surface. And with the addition of echosounder technology that allows us to map the prey field, we can now link feeding events with characteristics of the prey present in the area [9]. With this progression of technology, curiosity and insight we now know that blue whales are not indiscriminate grazers, but instead pass up small patches of krill in favor of large, dense aggregations where they will get the most energetic bang for their buck.

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 advent of unmanned aerial systems (UAS, a.k.a. “drones”) have provided yet another unique perspective on the lives of these whales. In 2016, our New Zealand blue whale team recorded nursing behavior between a mother and calf. In 2017, we were able to capture surface lunge feeding behavior from an aerial perspective, both for the first time.

A blue whale lunges on an aggregation of krill. UAS piloted by Todd Chandler.

Through innovative approaches, we are beginning to understand the lives of these mysterious giants. As is true for many things, the more we learn, the more questions we have. Through the GEMM Lab’s blue whale project, we have determined that a unique population of blue whales occupies the South Taranaki Bight region of New Zealand year-round; they do not simply migrate through as their current threat classification status indicates [10]. But what are their distribution patterns? Can we predict when and where whales are most likely to be in the South Taranaki Bight? Does this population have a different foraging strategy than their Californian, Chilean, or Antarctic counterparts? These are the things we are working on unraveling, and that will aid in their conservation. In the meantime, I’ll keep musing about what we don’t know, and remember to keep marveling at what we do know about the largest creatures on earth.

A blue whale mother and calf surface near Farewell Spit, New Zealand. Photo by D. Barlow.

References:

Clapham, P. J., Young, S. B. & Brownell Jr., R. L. Baleen whales: conservation issues and the status of the most endangered populations. Mamm. Rev. 29, 37–60 (1999).
Branch, T. a, Matsuoka, K. & Miyashita, T. Evidence for increases in Antarctic blue whales based on baysian modelling. Mar. Mammal Sci. 20, 726–754 (2004).
Branch, T. A. et al. Past and present distribution, densities and movements of blue whales Balaenoptera musculus in the Southern Hemisphere and northern Indian Ocean. Mammal Review 37, 116–175 (2007).
George, J. C. et al. Age and growth estimates of bowhead whales (Balaena mysticetus) via aspartic acid racemization. Can. J. Zool. 77, 571–580 (1998).
Sears, R. et al. Photographic identification of the Blue Whale (Balaenoptera musculus) in the Gulf of St. Lawrence, Canada. Report of the International Whaling Commission Special Issue 335–342 (1990).
Kenney, R. D., Hyman, M. A. M., Owen, R. E., Scott, G. P. & Winn, H. E. Estimation of prey densities required by Western North Atlantic right whales. Mar. Mammal Sci. 2, 1–13 (1986).
Acevedo-Gutierrez, A., Croll, D. A. & Tershy, B. R. High feeding costs limit dive time in the largest whales. J. Exp. Biol. 205, 1747–1753 (2002).
Johnson, M. P. & Tyack, P. L. A digital acoustic recording tag for measuring the response of wild marine mammals to sound. IEEE J. Ocean. Eng. 28, 3–12 (2003).
Hazen, E. L., Friedlaender, A. S. & Goldbogen, J. A. Blue whales (Balaenoptera musculus) optimize foraging efficiency by balancing oxygen use and energy gain as a function of prey density. Sci. Adv. 1, e1500469–e1500469 (2015).
Baker, C. S. et al. Conservation status of New Zealand marine mammals, 2013. (2016).

Can we talk about how cool sea otters are?

By Dominique Kone, Masters Student in Marine Resource Management

A couple of months ago, I wrote a blog introducing our new project, and my thesis, on the potential to reintroduce sea otters to the Oregon coast. In that blog, I expressed that in order to develop a successful reintroduction plan, scientists and managers need to have a sound understanding of sea otter ecology and the current state of Oregon’s coastal ecosystems. As a graduate student conducting a research-based thesis in a management program, I’m constantly fretting over the applicability of my research to inform decision-making processes. However, in the course of conducting my research, I sometimes forget just how COOL sea otters are. Therefore, in this blog, I wanted to take the opportunity to nerd out and provide you with my top five favorite facts about these otterly adorable creatures.

Without further ado, here are my top five favorite facts about sea otters:

Sea otters eat a lot. Previous studies show that an individual sea otter eats up to 30% of its own body weight in food each day[1][2]. With such high caloric demands, sea otters spend a great deal of their time foraging the seafloor for a variety of prey species, and have been shown to decrease prey densities in their local habitat significantly. Sea otters are famously known for their taste for sea urchins. Yet, these voracious predators also consume clams, sea stars, crabs, and a variety of other small invertebrate species[3][4].
Photo Credit: Katherine Johns via www.listal.com
Individuals are specialists, but can change their diet. Sea otters typically show individual foraging specialization – which means an individual predominantly eats a select few species of prey. However, this doesn’t mean an otter can’t switch or consume other types of prey as needed. In fact, while individuals tend to be specialists, on a population or species level, sea otters are actually generalist predators[5][6]. Past studies that looked at the foraging habits of expanding sea otter populations show that as populations expand into unoccupied territory, they typically eat a limited number of prey. But as populations grow and become more established, the otters will start to diversify their diet, suggesting intra-specific competition[3][7].
Sea otters exert a strong top-down force. Top-down forcing is one of the most important concepts we must acknowledge when discussing sea otter ecology. With top-down forcing, consumers at the top of the food chain depress the trophic level on which they feed, and this feeding indirectly increases the abundance of the next lower trophic level, resulting in a cascading effect[8]. The archetype example of this phenomenon is the relationship between sea otters, sea urchins, and kelp forests. This relationship goes as follows: sea otters consume sea urchin, and sea urchins graze on kelp. Therefore, sea otters reduce sea urchin densities by direct predation, thereby mediating grazing pressure on kelp. This indirect effect allows kelp to grow more abundantly, which is why we often see relatively productive kelp forests when sea otters are present[9]. This top-down forcing also has important implications for the whole ecosystem, as I’ll explain in my next fact.
Pictured: sea urchin dominated seascape in habitat without sea otters. Photo Credit: BISHOPAPPS via Ohio State University.
Sea otters help restore ecosystems, and associated ecosystem services. In kelp habitat where sea otters have been removed, we often see high densities of sea urchins and low biomasses of kelp. In this case, sea urchins have no natural predators to keep their populations in check and therefore completely decimate kelp forests. However, what we’ve learned is that when sea otters “reclaim” previously occupied habitats or expand into unoccupied territory, they can have remarkable restorative effects because their predation on sea urchins allows for the regrowth of kelp forest[10]. Additionally, with the restoration of key ecosystems like kelp forests, we can see a variety of other indirect benefits – such as increased biodiversity, refuge for fish nurseries and commercially-important species, and carbon sequestration[11][12][13]. The structure of nearshore ecosystems and communities change drastically with the addition or removal of sea otters, which is why they’re often referred to as keystone species.
Photo Credit: University of California, Santa Barbara.
Sea otters are most often associated with coastal kelp forests, but they can also exist in other types of habitats and ecosystems. In addition to kelp dominated ecosystems, sea otters are known to use estuaries and bays, seagrass beds, and swim over a range of bottom substrates[14][15]. As evidenced by previous studies, sea otters exert similar top-down forces in non-kelp ecosystems, as they do within kelp forests. One study found that sea otters also had restorative effects on seagrass beds within estuaries, where they consumed different types of prey (i.e., crabs instead of urchins), demonstrating that sea otters play a significant keystone role in seagrass habitats as well [12]. Findings such as these are vitally important to understanding (1) where sea otters are capable of living relative to habitat characteristics, and (2) how recovering or expanding sea otter populations may impact ecosystems and habitats in which they don’t currently exist, such as the Oregon coast.

Pictured: sea otter swimming through eel grass at Elkhorn Slough, California. Photo Credit: Kip Evans Photography.

Well, there you have it – my top five favorite facts about sea otters. This list is by no means exhaustive of all there is to know about sea otter ecology, and isn’t enough information to develop an informative reintroduction plan. However, a successful reintroduction plan will rely heavily on these underlying ecological characteristics of sea otters, in addition to the current state of Oregon’s nearshore ecosystems. As someone who constantly focuses on the relationship between scientific research and management and conservation, it’s nice every now and then to take a step back and just simply appreciate sea otters for being, well, sea otters.

References:

[1] Costa, D. P. 1978. The ecological energetics, water, and electrolyte balance of the California sea otter (Enhydra lutris). Ph.D. dissertation, University of California, Santa Cruz.

[2] Reidman, M. L. and J. A. Estes. 1990. The sea otter (Enhydra lutris): behavior, ecology, and natural history. United States Department of the Interior, Fish and Wildlife Service, Biological Report. 90: 1-126.

[3] Laidre, K.L. and R. J. Jameson. 2006. Foraging patterns and prey selection in an increasing and expanding sea otter population. Journal of Mammology. 87(4): 799-807.

[4] Estes, J. A., Jameson, R.J., and B. R. Rhode. 1982. Activity and prey election in the sea otter: influence of population status on community structure. The American Naturalist. 120(2): 242-258.

[5] Tinker, M. T., Costa, D. P., Estes, J. A., and N. Wieringa. 2007. Individual dietary specialization and dive behavior in the California sea otter: using archival time-depth data to detect alternative foraging strategies. Deep-Sea Research Part II. (54):330-342.

[6] Newsome et al. 2009. Using stable isotopes to investigate individual diet specialization in California sea otters (Enhydra lutris nereis). Ecology. 90(4): 961-974.

[7] Ostfeld, R. S. 1982. Foraging strategies and prey switching in the California sea otter. Oecologia. 53(2): 170-178.

[8] Paine, R. T. 1980. Food webs: linkage, interaction strength and community infrastructure. The Journal of Animal Ecology. 49(3): 666-685.

[9] Estes, J. A. and J.F. Palmisano. 1974. Sea otters: their role in structuring nearshore communities. Science. 185(4156): 1058-1060.

[10] Estes, J. A., and D. O. Duggins. 1995. Sea otters and kelp forests in Alaska: generality and variation in a community ecological paradigm. Ecological Monographs. 65(1): 75-100.

[11] Wilmers, C. C., Estes, J. A., Edwards, M., Laidre, K. L., and B. Konar. 2012. Do trophic cascades affect the storage and flux of atmospheric carbon? An analysis of sea otters and kelp forests. Frontiers in Ecology and the Environment. 10(8): 409-415.

[12] Hughes et al. 2014. Recovery of a top predator mediate negative eutrophic effects on seagrass. Proceedings of the National Academy of Sciences. 110(38): 15313-15318.

[13] Lee, L.C., Watson, J. C., Trebilco, R., and A. K. Salomon. Indirect effects and prey behavior mediate interactions between an endangered prey and recovering predator. Ecosphere. 7(12).

[14] Laidre, K. L., Jameson, R. J., Gurarie, E., Jeffries, S. J., and H. Allen. 2009. Spatial habitat use patterns of sea otters in coastal Washington. Journal of Mammalogy. 90(4): 906-917.

[15] Lafferty, K. D., and M. T. Tinker. 2014. Sea otters are recolonizing southern California in fits and starts. Ecosphere. 5(5).

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