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.

Source: Suzi Eszterhas

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.

Source: Mike Baird.

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.

Source: Trover

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.

Source: Suzi Eszterhas

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.

 

 

The Recipe for a “Perfect” Marine Mammal and Seabird Cruise

By Alexa Kownacki, Ph.D. Student, OSU Department of Fisheries and Wildlife, Geospatial Ecology of Marine Megafauna Lab

Science—and fieldwork in particular—is known for its failures. There are websites, blogs, and Twitter pages dedicated to them. This is why, when things go according to plan, I rejoice. When they go even better than expected, I practically tear up from amazement. There is no perfect recipe for a great marine mammal and seabird research cruise, but I would suggest that one would look like this:

 A Great Marine Mammal and Seabird Research Cruise Recipe:

  • A heavy pour of fantastic weather
    • Light on the wind and seas
    • Light on the glare
  • Equal parts amazing crew and good communication
  • A splash of positivity
  • A dash of luck
  • A pinch of delicious food
  • Heaps of marine mammal and seabird sightings
  • Heat to approximately 55-80 degrees F and transit for 10 days along transects at 10-12 knots
The end of another beautiful day at sea on the R/V Shimada. Image source: Alexa K.

The Northern California Current Ecosystem (NCCE) is a highly productive area that is home to a wide variety of cetacean species. Many cetaceans are indicator species of ecosystem health as they consume large quantities of prey from different levels in trophic webs and inhabit diverse areas—from deep-diving beaked whales to gray whales traveling thousands of miles along the eastern north Pacific Ocean. Because cetacean surveys are a predominant survey method in large bodies of water, they can be extremely costly. One alternative to dedicated cetacean surveys is using other research vessels as research platforms and effort becomes transect-based and opportunistic—with less flexibility to deviate from predetermined transects. This decreases expenses, creates collaborative research opportunities, and reduces interference in animal behavior as they are never pursued. Observing animals from large, motorized, research vessels (>100ft) at a steady, significant speed (>10kts/hour), provides a baseline for future, joint research efforts. The NCCE is regularly surveyed by government agencies and institutions on transects that have been repeated nearly every season for decades. This historical data provides critical context for environmental and oceanographic dynamics that impact large ecosystems with commercial and recreational implications.

My research cruise took place aboard the 208.5-foot R/V Bell M. Shimada in the first two weeks of May. The cruise was designated for monitoring the NCCE with the additional position of a marine mammal observer. The established guidelines did not allow for deviation from the predetermined transects. Therefore, mammals were surveyed along preset transects. The ship left port in San Francisco, CA and traveled as far north as Cape Meares, OR. The transects ranged from one nautical mile from shore and two hundred miles offshore. Observations occurred during “on effort” which was defined as when the ship was in transit and moving at a speed above 8 knots per hour dependent upon sea state and visibility. All observations took place on the flybridge during conducive weather conditions and in the bridge (one deck below the flybridge) when excessive precipitation was present. The starboard forward quarter: zero to ninety degrees was surveyed—based on the ship’s direction (with the bow at zero degrees). Both naked eye and 7×50 binoculars were used with at least 30 percent of time binoculars in use. To decrease observer fatigue, which could result in fewer detected sightings, the observer (me) rotated on a 40 minutes “on effort”, 20 minutes “off effort” cycle during long transits (>90 minutes).

Alexa on-effort using binoculars to estimate the distance and bearing of a marine mammal sighted off the starboard bow. Image source: Alexa K.

Data was collected using modifications to the SEEbird Wincruz computer program on a ruggedized laptop and a GPS unit was attached. At the beginning of each day and upon changes in conditions, the ship’s heading, weather conditions, visibility, cloud cover, swell height, swell direction, and Beaufort sea state (BSS) were recorded. Once the BSS or visibility was worse than a “5” (1 is “perfect” and 5 is “very poor”) observations ceased until there was improvement in weather. When a marine mammal was sighted the latitude and longitude were recorded with the exact time stamp. Then, I noted how the animal was sighted—either with binoculars or naked eye—and what action was originally noticed—blow, splash, bird, etc. The bearing and distance were noted using binoculars. The animal was given three generalized behavior categories: traveling, feeding, or milling. A sighting was defined as any marine mammal or group of animals. Therefore, a single sighting would have the species and the best, high, and low estimates for group size.

By my definitions, I had the research cruise of my dreams. There were moments when I imagined people joining this trip as a vacation. I *almost* felt guilty. Then, I remember that after watching water for almost 14 hours (thanks to the amazing weather conditions), I worked on data and reports and class work until midnight. That’s the part that no one talks about: the data. Fieldwork is about collecting data. It’s both what I live for and what makes me nervous. The amount of time, effort, and money that is poured into fieldwork is enormous. The acquisition of the data is not as simple as it seems. When I briefly described my position on this research cruise to friends, they interpret it to be something akin to whale-watching. To some extent, this is true. But largely, it’s grueling hours that leave you fatigued. The differences between fieldwork and what I’ll refer to as “everything else” AKA data analysis, proposal writing, manuscript writing, literature reviewing, lab work, and classwork, are the unbroken smile, the vaguely tanned skin, the hours of laughter, the sea spray, and the magical moments that reassure me that I’ve chosen the correct career path.

Alexa photographing a gray whale at sunset near Newport, OR. Image source: Alexa K.

This cruise was the second leg of the Northern California Current Ecosystem (NCCE) survey, I was the sole Marine Mammal and Seabird Observer—a coveted position. Every morning, I would wake up at 0530hrs, grab some breakfast, and climb to the highest deck: the fly-bridge. Akin to being on the top of the world, the fly-bridge has the best views for the widest span. From 0600hrs to 2000hrs I sat, stood, or danced in a one-meter by one-meter corner of the fly-bridge and surveyed. This visual is why people think I’m whale watching. In reality, I am constantly busy. Nonetheless, I had weather and seas that scientists dream about—and for 10 days! To contrast my luck, you can read Florence’s blog about her cruise. On these same transects, in February, Florence experienced 20-foot seas with heavy rain with very few marine mammal sightings—and of those, the only cetaceans she observed were gray whales close to shore. That starkly contrasts my 10 cetacean species with upwards of 45 sightings and my 20-minute hammock power naps on the fly-bridge under the warm sun.

Pacific white-sided dolphins traveling nearby. Image source: Alexa K.

Marine mammal sightings from this cruise included 10 cetacean species: Pacific white-sided dolphin, Dall’s porpoise, unidentified beaked whale, Cuvier’s beaked whale, gray whale, Minke whale, fin whale, Northern right whale dolphin, blue whale, humpback whale, and transient killer whale and one pinniped species: northern fur seal. What better way to illustrate these sightings than with a map? We are a geospatial lab after all.

Cetacean Sightings on the NCCE Cruise in May 2018. Image source: Alexa K.

This map is the result of data collection. However, it does not capture everything that was observed: sea state, weather, ocean conditions, bathymetry, nutrient levels, etc. There are many variables that can be added to maps–like this one (thanks to my GIS classes I can start adding layers!)–that can provide a better understanding of the ecosystem, predator-prey dynamics, animal behavior, and population health.

The catch from a bottom trawl at a station with some fish and a lot of pyrosomes (pink tube-like creatures). Image source: Alexa K.

Being a Ph.D. student can be physically and mentally demanding. So, when I was offered the opportunity to hone my data collection skills, I leapt for it. I’m happiest in the field: the wind in my face, the sunshine on my back, surrounded by cetaceans, and filled with the knowledge that I’m following my passion—and that this data is contributing to the greater scientific community.

Humpback whale photographed traveling southbound. Image source: Alexa K.

Forecasting blue whale presence: Small steps toward big goals

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

In 2013, Leigh first published a hypothesis that the South Taranaki Bight region between New Zealand’s North and South Islands is important habitat for blue whales  (Torres 2013). Since then, we have collected three years of data and conducted dedicated analyses, so we now understand that a unique population of blue whales is found in New Zealand, and that they are present in the South Taranaki Bight year-round (Barlow et al. in press).

A blue whale surfaces in the South Taranaki Bight. Photo by Leigh Torres.

This research has garnered quite a bit of political and media attention. A major platform item for the New Zealand Green Party around the last election was the establishment of a marine mammal sanctuary in the South Taranaki Bight. When the world’s largest seismic survey vessel began surveying the South Taranaki Bight this summer for more oil and gas reserves using tremendously loud airguns, there were rallies on the lawn in front of Parliament featuring a large inflatable blue whale that the protesters affectionately refer to as “Janet”. Needless to say, blue whales have made their way into the spotlight in New Zealand.

Janet the inflatable blue whale accompanies protesters on the lawn in front of Parliament in Wellington, New Zealand. Image credit: Greenpeace.

Now that we know there is a unique population of blue whales in New Zealand, what is next? What’s next for me is an exciting combination of both ecology and conservation. If an effective sanctuary is to be implemented, it needs to be more than a simple box drawn on a map to check off a political agenda item—the sanctuary should be informed by our best ecological knowledge of the blue whales and their habitat.

In July, Leigh and I will attend the Society for Conservation Biology meeting in Wellington, New Zealand, and I’ll be giving a presentation titled “Cloudy with a chance of whales: Forecasting blue whale presence based on tiered, bottom-up models”. I’ll be the first to admit, I am not yet forecasting blue whale presence. But I am working my way there, step-by-step, through this tiered, bottom-up approach. In cetacean habitat modeling, we often assume that whale distribution on a foraging ground is determined by their prey’s distribution, and that satellite images of temperature and chlorophyll-a provide an accurate picture of what is going on below the surface. Is this true? With our three years of data including in situ oceanography, krill hydroacoustics, and blue whale distribution and behavior, we are in a unique position to test some of those assumptions, as well as provide managers with an informed management tool to predict blue whale distribution.

What questions will we ask using our data? Firstly, can in situ oceanography (i.e., thermocline depth and temperature, mixed layer depth) predict the distribution and density of blue whale prey (krill)? Then, can those prey patterns be accurately predicted in the absence of oceanographic measurements, using just satellite images? Next, we’ll bring the blue whales back into the picture to ask: can we predict blue whale distribution based on our in situ measurements of oceanography and prey? And finally, in the absence of in situ measurements (which is most often the case), can we forecast where the whales will be based just on remotely-sensed images of the region?

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

So, cloudy with a chance of whales? Well, you’ll have to stay tuned for that story in the coming months. In the meantime, I can tell you that as daunting as it is to aggregate so many data streams, each step of the way has a piece of the story to tell. I can’t wait to see how it falls together, both from an ecological modeling perspective and a conservation management objective.

A blue whale surfaces in front of a floating production storage and offloading (FPSO) vessel which services the oil rigs in the South Taranaki Bight. Photo by Dawn Barlow.

 

References:

Torres, L. G. (2013). Evidence for an unrecognised blue whale foraging ground in New Zealand. New Zealand Journal of Marine and Freshwater Research47(2), 235-248.

Barlow, D. R., Torres, L. G., Hodge, K. B., Steel, D. Baker, C. S., Chandler, T. E., Bott, N., Constantine, R., Double, M. C., Gill, P., Glasgow, D., Hamner, R. M., Lilley, C., Ogle, M., Olson, P. A., Peters, C., Stockin, K. A., Tessaglia-Hymes, C. T., Klinck, H. (in press). Documentation of a New Zealand blue whale population based on multiple lines of evidence. Endangered Species Research. 

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.

Source: The Tribune.

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:

  1. 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.
Source: The Telegraph.
  1. 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.

 

  1. 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).
Source: Save our Seas Foundation.
  1. 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.

Source: Doretta Smith.

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.

 

 

Sea Otter Management in the U.S.

By Dominique Kone, Masters Student in Marine Resource Management

Since the first official legal protections in 1911, the U.S. has made great strides in recovering sea otter populations. While much of this progress is due to increased emphasis on understanding sea otter behavior, biology, and ecology, there are also several policies that have been just as instrumental in making sea otter conservation efforts successful. Here, I provide a brief overview of the current legal and regulatory policies used to manage sea otters in the U.S. and explain why having a base understanding of these tools can help our lab as we look into the potential reintroduction of sea otters to the Oregon coast.

Sea otter with pup, Prince William Sound, Alaska. Source: Patrick J. Endres

When we talk about sea otter management in the U.S., the two most obvious laws that come to mind are the Marine Mammal Protection Act (MMPA) and the Endangered Species Act (ESA). In short, the MMPA seeks to prevent the take – including kill, harass, capture, or disturb – or importation of marine mammals and marine mammal products[1]. While the ESA seeks to protect and recover imperiled species – not just marine mammals – and the ecosystems which they depend upon[2]. Both laws are similar in the sense that their primary objectives are to protect and recover at-risk species. However, marine mammals will always be protected under the MMPA, but will only be protected under the ESA if the species is considered threatened or endangered.

On the federal level, the U.S. Fish and Wildlife Service (the Service) is primarily responsible for managing sea otter populations. In the U.S., we manage sea otter populations as five distinct stocks, which differ in their population size and geographic distribution – located in California, Washington, and Alaska state waters (Fig. 1). Because sea otters are divided into these single stocks, management decisions – such as recovery targets or reintroductions – are made on a stock-by-stock basis and are dependent on the stock’s population status. Currently, two of these stocks are federally-listed as threatened under the ESA. Therefore, these two stocks are granted protection under both the ESA and MMPA, while the remaining three stocks are only protected by the MMPA (at the federal level; state management may also apply).

Figure 1. Distribution (approximations of population centers) of sea otter stocks in the U.S. (SW = Southwest Alaskan; SC = Southcentral Alaskan; SE = Southeast Alaskan; WA = Washington, SCA = Southern/Californian)

While the MMPA and ESA are important federal laws, I would be remiss if I didn’t mention the important role that state laws and state agencies have in managing sea otters. According to the MMPA and ESA, if a state develops and maintains a conservation or recovery program with protections consistent with the standards and policies of the MMPA and/or ESA, then the Service may transfer management authority over to the state1,2. However, typically, the Service has opted to manage any stocks listed under the ESA, while states manage all other stocks not listed under the ESA.

Sea otter management in the states of Washington and California is a clear example of this dichotomy. The Washington sea otter stock is not listed under the ESA, and is therefore, managed by the Washington Department of Fish and Wildlife (WDFW), which developed the stock’s recovery plan[3]. In contrast, sea otters along the California coast are listed as threatened under the ESA, and the Service primarily manages the stock’s recovery[4].

Interestingly, sea otter management in Alaska is an exception to this rule. The Southeast and Southcentral sea otter stocks are not listed under the ESA, yet are still managed by the Service. However, the state recognizes sea otters as a species of greatest conservation need in the state’s Wildlife Action Plan, which acts as a recommendation framework for the management and protection of important species and ecosystems[5]. Therefore, even though the state is not the primary management authority for sea otters by law, they still play a role in protecting Alaskan sea otter populations through this action plan.

Table 1. Federal and state listing status of all sea otter stocks within U.S. coastal waters.

States have also implemented their own laws for protecting at-risk species. For instance, while the Washington sea otter stock is not listed under the ESA, it is listed as endangered under Washington state law4. This example raises an important example demonstrating that even if a stock isn’t federally-listed, it may still be protected on the state level, and is always protected under the MMPA. Therefore, if the federal and state listing status do not match, which is the case for most sea otter stocks in the U.S. (Table 1.), the stock still receives management protection at some level.

So why does this matter?

Each of the previously mentioned laws are prohibitive in nature, where the objectives are to prevent and discourage activities which may harm the stock of interest. Yet, agencies may grant exceptions – in the form of permits – for activities, such as scientific research, translocations, commercial/recreational fisheries operations, etc. The permit approval process will oftentimes depend on: (1) the severity or likelihood of that action to harm the species, (2) the species’ federal and state listing status, and (3) the unique approval procedures enforced by the agency. Activities that are perceived to have a high likelihood of harming a species, or involve a species that’s listed under the ESA, will likely require a longer and more arduous approval process.

A sea otter release in Monterey Bay, California. Source: Monterey Bay Aquarium Newsroom.

Understanding these various approval processes is vitally important for our work on the potential reintroduction of sea otters to Oregon because such an effort will no doubt require many permits and a thoughtful permit approval process. Each agency may have their own set of permits, administrative procedures, and approval processes. Therefore, it behooves us to have a clear understanding of these various processes relative to the state, agency, or stock involved. If, hypothetically, a stock is determined as a suitable candidate for reintroduction into Oregon waters, having this understanding will allow us to determine where our research can best inform the effort, what types of information and data are needed to inform the process, and to which agency or stakeholders we must communicate our research.

 

References:

[1] Marine Mammal Protection Act of 1972

[2] Endangered Species Act of 1973

[3] State of Washington. 2004. Sea Otter Recovery Plan. Washington Department of Fish and Wildlife: Wildlife Program

[4] U.S. Fish & Wildlife Service. 2003. Final Revised Recovery Plan for the Southern Sea Otter (Enydra lutris nereis).

[5] Alaska Department of Fish and Game. 2015. Alaska wildlife action plan. Juneau.

 

The Land of Maps and Charts: Geospatial Ecology

By Alexa Kownacki, Ph.D. Student, OSU Department of Fisheries and Wildlife, Geospatial Ecology of Marine Megafauna Lab

I love maps. I love charts. As a random bit of trivia, there is a difference between a map and a chart. A map is a visual representation of land that may include details like topology, whereas a chart refers to nautical information such as water depth, shoreline, tides, and obstructions.

Map of San Diego, CA, USA. (Source: San Diego Metropolitan Transit System)
Chart of San Diego, CA, USA. (Source: NOAA)

I have an intense affinity for visually displaying information. As a child, my dad traveled constantly, from Barrow, Alaska to Istanbul, Turkey. Immediately upon his return, I would grab our standing globe from the dining room and our stack of atlases from the coffee table. I would sit at the kitchen table, enthralled at the stories of his travels. Yet, a story was only great when I could picture it for myself. (I should remind you, this was the early 1990s, GoogleMaps wasn’t a thing.) Our kitchen table transformed into a scene from Master and Commander—except, instead of nautical charts and compasses, we had an atlas the size of an overgrown toddler and salt and pepper shakers to pinpoint locations. I now had the world at my fingertips. My dad would show me the paths he took from our home to his various destinations and tell me about the topography, the demographics, the population, the terrain type—all attribute features that could be included in common-day geographic information systems (GIS).

Uncle Brian showing Alexa where they were on a map of Maui, Hawaii, USA. (Photo: Susan K. circa 1995)

As I got older, the kitchen table slowly began to resemble what I imagine the set from Master and Commander actually looked like; nautical charts, tide tables, and wind predictions were piled high and the salt and pepper shakers were replaced with pencil marks indicating potential routes for us to travel via sailboat. The two of us were in our element. Surrounded by visual and graphical representations of geographic and spatial information: maps. To put my map-attraction this in even more context, this is a scientist who grew up playing “Take-Off”, a board game that was “designed to teach geography” and involved flying your fleet of planes across a Mercator projection-style mapboard. Now, it’s no wonder that I’m a graduate student in a lab that focuses on the geospatial aspects of ecology.

A precocious 3-year-old Alexa, sitting with the airplane pilot asking him a long list of travel-related questions (and taking his captain’s hat). Photo: Susan K.

So why and how did geospatial ecology became a field—and a predominant one at that? It wasn’t that one day a lightbulb went off and a statistician decided to draw out the results. It was a progression, built upon for thousands of years. There are maps dating back to 2300 B.C. on Babylonian clay tablets (The British Museum), and yet, some of the maps we make today require highly sophisticated technology. Geospatial analysis is dynamic. It’s evolving. Today I’m using ArcGIS software to interpolate mass amounts of publicly-available sea surface temperature satellite data from 1981-2015, which I will overlay with a layer of bottlenose dolphin sightings during the same time period for comparison. Tomorrow, there might be a new version of software that allows me to animate these data. Heck, it might already exist and I’m not aware of it. This growth is the beauty of this field. Geospatial ecology is made for us cartophiles (map-lovers) who study the interdependency of biological systems where location and distance between things matters.

Alexa’s grandmother showing Alexa (a very young cartographer) how to color in the lines. Source: Susan K. circa 1994

In a broader context, geospatial ecology communicates our science to all of you. If I posted a bunch of statistical outputs in text or even table form, your eyes might glaze over…and so might mine. But, if I displayed that same underlying data and results on a beautiful map with color-coded symbology, a legend, a compass rose, and a scale bar, you might have this great “ah-ha!” moment. That is my goal. That is what geospatial ecology is to me. It’s a way to SHOW my science, rather than TELL it.

Would you like to see this over and over again…?

A VERY small glimpse into the enormous amount of data that went into this map. This screenshot gave me one point of temperature data for a single location for a single day…Source: Alexa K.

Or see this once…?

Map made in ArcGIS of Coastal common bottlenose dolphin sightings between 1981-1989 with a layer of average sea surface temperatures interpolated across those same years. A picture really is worth a thousand words…or at least a thousand data points…Source: Alexa K.

For many, maps are visually easy to interpret, allowing quick message communication. Yet, there are many different learning styles. From my personal story, I think it’s relatively obvious that I’m, at least partially, a visual learner. When I was in primary school, I would read the directions thoroughly, but only truly absorb the material once the teacher showed me an example. Set up an experiment? Sure, I’ll read the lab report, but I’m going to refer to the diagrams of the set-up constantly. To this day, I always ask for an example. Teach me a new game? Let’s play the first round and then I’ll pick it up. It’s how I learned to sail. My dad described every part of the sailboat in detail and all I heard was words. Then, my dad showed me how to sail, and it came naturally. It’s only as an adult that I know what “that blue line thingy” is called. Geospatial ecology is how I SEE my research. It makes sense to me. And, hopefully, it makes sense to some of you!

Alexa’s dad teaching her how to sail. (Source: Susan K. circa 2000)
Alexa’s first solo sailboat race in Coronado, San Diego, CA. Notice: Alexa’s dad pushing the bow off the dock and the look on Alexa’s face. (Source: Susan K. circa 2000)
Alexa mapping data using ArcGIS in the Oregon State University Library. (Source: Alexa K circa a few minutes prior to posting).

I strongly believe a meaningful career allows you to highlight your passions and personal strengths. For me, that means photography, all things nautical, the great outdoors, wildlife conservation, and maps/charts.  If I converted that into an equation, I think this is a likely result:

Photography + Nautical + Outdoors + Wildlife Conservation + Maps/Charts = Geospatial Ecology of Marine Megafauna

Or, better yet:

? + ⚓ + ? + ? + ? =  GEMM Lab

This lab was my solution all along. As part of my research on common bottlenose dolphins, I work on a small inflatable boat off the coast of California (nautical ✅, outdoors ✅), photograph their dorsal fin (photography ✅), and communicate my data using informative maps that will hopefully bring positive change to the marine environment (maps/charts ✅, wildlife conservation✅). Geospatial ecology allows me to participate in research that I deeply enjoy and hopefully, will make the world a little bit of a better place. Oh, and make maps.

Alexa in the field, putting all those years of sailing and chart-reading to use! (Source: Leila L.)

 

Living the Dream – life as a marine mammal observer

By Florence Sullivan, MSc.

Living the dream as a marine mammal observer onboard the R/V Bell Shimada Photo credit: Dave Jacobsen

I first learned that “Marine Mammal Observer” was a legitimate career field during the summer after my junior year at the University of Washington.  I had the good fortune to volunteer for the BASIS fisheries-oceanography survey onboard the R/V Oscar Dyson where I met two wonderful bird observers who taught me how to identify various pelagic bird species and clued me in to just how diverse the marine science job market can be. After the cruise, younger Florence went off with an expanded world view and a small dream that maybe someday she could go out to sea and survey for marine mammals on a regular basis (and get paid for it?!).  Eight years later, I am happy to report that I have just spent the last week as the marine mammal observer on the North California Current Survey on the Dyson’s sister ship, the R/V Bell M. Shimada.  While we may not have seen as many marine mammals as I would have liked, the experience has still been everything younger Florence hoped it would be.

Finally leaving port a few days behind schedule due to stormy weather! photo credit: Florence Sullivan

If you’ve ever wondered why the scientists in your life may refer to summer as “field work season”, it’s because attempting to do research outside in the winter is an exercise in frustration, troubleshooting, and flexibility. Case in point; this cruise was supposed to sail away from port on the 24th of February, but did not end up leaving until the 27th due to bad weather.  This weather delay meant that we had to cut some oceanographic stations we would like to have sampled, and even when we made it out of the harbor, the rough weather made it impossible to sample some of the stations we still had left on our map.  That being said, we still got a lot of good work done!

The original station map. The warm colors are the west coast of the US, the cold colors are the ocean, and the black dots are planned survey stations

The oceanographers were able to conduct CTD casts at most planned stations, as well as sample the water column with a vertical zooplankton net, a HAB net (for looking for the organisms that cause Harmful Algal Blooms),  and a Bongo Net (a net that specializes in getting horizontal samples of the water column).  When it wasn’t too windy, they were also able to sample with the Manta net (a net specialized for surface sampling – it looks like a manta ray’s mouth) and at certain near-shore stations they did manage to get some bottom beam trawls in to look at the benthic community of fishes and invertebrates.  All this was done while dodging multitudes of crab pots and storm fronts.  The NOAA corps officers who drive the boat, and the deck crew who handle all the equipment deployments and retrievals really did their utmost to make sure we were able to work.

Stormy seas make for difficult sampling conditions! photo credit: Florence Sullivan

For my part, I spent the hours between stations searching the wind-tossed waves for any sign of marine mammals. Over the course of the week, I saw a few Northern fur seals, half a dozen gray whales, and a couple of unidentified large cetaceans.  When you think about the productivity of the North Pacific Ecosystem this may not seem like very much.  But remember, it is late winter, and I do not have x-ray vision to see through the waves.  It is likely that I missed a number of animals simply because the swell was too large, and when we calculate our “detection probability” these weather factors will be taken into account. In addition, many of our local marine mammals are migrators who might be in warmer climates, or are off chasing different food sources at the moment.  In ecology, when you want to know how a population of animals is distributed across a land- or sea-scape, it is just as important to understand where the animals are NOT as where they ARE. So all of this “empty” water was very important to survey simply because it helps us refine our understanding of where animals don’t want to be.  When we know where animals AREN’T we can ask better questions about why they occur where they ARE.

Black Footed Albatross soars near the boat. Photo credit: Florence Sullivan

Notable species of the week aside from the marine mammals include Laysan and Black Footed Albatrosses, a host of Vellella vellella (sailor by the wind hydroid colonies) and the perennial favorite of oceanographers; the shrinking Styrofoam cup.  (See pictures)

We sent these styrofoam cups down to 1800 meters depth. The pressure at those depths causes all the air to escape from the styrofoam, and it shrinks! This is a favorite activity of oceanographers to demonstrate the effects on increased pressure!

These sorts of interdisciplinary cruises are quite fun and informative to participate in because we can build a better picture of the ecosystem as a whole when we use a multitude of methods to explore it.  This strength of cooperation makes me proud to add my little piece to the puzzle. As I move forward in life, whether I get to be the marine mammal observer, the oceanographer, or perhaps an educator, I will always be glad to contribute to collaborative research.

 

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:

  1. 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).
  2. 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).
  3. 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).
  4. 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).
  5. 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).
  6. 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).
  7. 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).
  8. 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).
  9. 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).
  10. 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.

Photo Credit: Point Lobos Foundation

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

  1. 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
  2. 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].
  3. 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.
  4. 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.
  5. 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).

 

What REALLY is a Wildlife Biologist?

By Alexa Kownacki, Ph.D. Student, OSU Department of Fisheries and Wildlife, Geospatial Ecology of Marine Megafauna Lab

The first lecture slide. Source: Lecture1_Population Dynamics_Lou Botsford

This was the very first lecture slide in my population dynamics course at UC Davis. Population dynamics was infamous in our department for being an ultimate rite of passage due to its notoriously challenging curriculum. So, when Professor Lou Botsford pointed to his slide, all 120 of us Wildlife, Fish, and Conservation Biology majors, didn’t know how to react. Finally, he announced, “This [pointing to the slide] is all of you”. The class laughed. Lou smirked. Lou knew.

Lou knew that there is more truth to this meme than words could express. I can’t tell you how many times friends and acquaintances have asked me if I was going to be a park ranger. Incredibly, not all—or even most—wildlife biologists are park rangers. I’m sure that at one point, my parents had hoped I’d be holding a tiger cub as part of a conservation project—that has never happened. Society may think that all wildlife biologists want to walk in the footsteps of the famous Steven Irwin and say thinks like “Crikey!”—but I can’t remember the last time I uttered that exclamation with the exception of doing a Steve Irwin impression. Hollywood may think we hug trees—and, don’t get me wrong, I love a good tie-dyed shirt—but most of us believe in the principles of conservation and wise-use A.K.A. we know that some trees must be cut down to support our needs. Helicoptering into a remote location to dart and take samples from wild bear populations…HA. Good one. I tell myself this is what I do sometimes, and then the chopper crashes and I wake up from my dream. But, actually, a scientist staring at a computer with stacks of papers spread across every surface, is me and almost every wildlife biologist that I know.

The “dry lab” on the R/V Nathaniel B. Palmer en route to Antarctica. This room full of technology is where the majority of the science takes place. Drake Passage, International Waters in August 2015. Source: Alexa Kownacki

There is an illusion that wildlife biologists are constantly in the field doing all the cool, science-y, outdoors-y things while being followed by a National Geographic photojournalist. Well, let me break it to you, we’re not. Yes, we do have some incredible opportunities. For example, I happen to know that one lab member (eh-hem, Todd), has gotten up close and personal with wild polar bear cubs in the Arctic, and that all of us have taken part in some work that is worthy of a cover image on NatGeo. We love that stuff. For many of us, it’s those few, memorable moments when we are out in the field, wearing pants that we haven’t washed in days, and we finally see our study species AND gather the necessary data, that the stars align. Those are the shining lights in a dark sea of papers, grant-writing, teaching, data management, data analysis, and coding. I’m not saying that we don’t find our desk work enjoyable; we jump for joy when our R script finally runs and we do a little dance when our paper is accepted and we definitely shed a tear of relief when funding comes through (or maybe that’s just me).

A picturesque moment of being a wildlife biologist: Alexa and her coworker, Jim, surveying migrating gray whales. Piedras Blancas Light Station, San Simeon, CA in May 2017. Source: Alexa Kownacki.

What I’m trying to get at is that we accepted our fates as the “scientists in front of computers surrounded by papers” long ago and we embrace it. It’s been almost five years since I was a senior in undergrad and saw this meme for the first time. Five years ago, I wanted to be that scientist surrounded by papers, because I knew that’s where the difference is made. Most people have heard the quote by Mahatma Gandhi, “Be the change that you wish to see in the world.” In my mind, it is that scientist combing through relevant, peer-reviewed scientific papers while writing a compelling and well-researched article, that has the potential to make positive changes. For me, that scientist at the desk is being the change that he/she wish to see in the world.

Scientists aboard the R/V Nathaniel B. Palmer using the time in between net tows to draft papers and analyze data…note the facial expressions. Antarctic Peninsula in August 2015. Source: Alexa Kownacki.

One of my favorite people to colloquially reference in the wildlife biology field is Milton Love, a research biologist at the University of California Santa Barbara, because he tells it how it is. In his oh-so-true-it-hurts website, he has a page titled, “So You Want To Be A Marine Biologist?” that highlights what he refers to as, “Three really, really bad reasons to want to be a marine biologist” and “Two really, really good reasons to want to be a marine biologist”. I HIGHLY suggest you read them verbatim on his site, whether you think you want to be a marine biologist or not because they’re downright hilarious. However, I will paraphrase if you just can’t be bothered to open up a new tab and go down a laugh-filled wormhole.

Really, Really Bad Reasons to Want to be a Marine Biologist:

  1. To talk to dolphins. Hint: They don’t want to talk to you…and you probably like your face.
  2. You like Jacques Cousteau. Hint: I like cheese…doesn’t mean I want to be cheese.
  3. Hint: Lack thereof.

Really, Really Good Reasons to Want to be a Marine Biologist:

  1. Work attire/attitude. Hint: Dress for the job you want finally translates to board shorts and tank tops.
  2. You like it. *BINGO*
Alexa with colleagues showing the “cool” part of the job is working the zooplankton net tows. This DOES have required attire: steel-toed boots, hard hat, and float coat. R/V Nathaniel B. Palmer, Antarctic Peninsula in August 2015. Source: Alexa Kownacki.

In summary, as wildlife or marine biologists we’ve taken a vow of poverty, and in doing so, we’ve committed ourselves to fulfilling lives with incredible experiences and being the change we wish to see in the world. To those of you who want to pursue a career in wildlife or marine biology—even after reading this—then do it. And to those who don’t, hopefully you have a better understanding of why wearing jeans is our version of “business formal”.

A fieldwork version of a lab meeting with Leigh Torres, Tom Calvanese (Field Station Manager), Florence Sullivan, and Leila Lemos. Port Orford, OR in August 2017. Source: Alexa Kownacki.