Dive Into Your Imagination

Brent Stewart is a Senior Research Scientist at the Hubbs-SeaWorld Research Institute, and a respected expert on the satellite tagging of marine vertebrates around the world!  Not only has he studied everything from seabirds to elephant seals, but he is also an integral part of the Maldives Whale Shark Research Programme, as well as other whale shark studies around the world!

Having done research all over the world, tell us about some of your findings!  What has been your most fascinating discovery so far? 
Perhaps the most fascinating discovery was one my colleague Robert DeLong and I made in the early 1990s that northern elephant seals make two long distance foraging migrations each year between the Southern California Channel Islands (where they breed and molt) and distant foraging areas in the north and central eastern Pacific Ocean AND that males and females are segregated during these migrations AND that they dive continually throughout these migrations AND that they rarely breathe while living mostly at depths of 1000 to 5000 feet for 8 to 10 months a year.  When we discovered these things, we had a difficult time believing it and just as difficult a time understanding how they do these things singly, even more all at the same time.

One of the most awesome things has been to witness the consistent increase in abundance and expansion of breeding distribution of the northern elephant seal each year for the past 30+ years, a species that was presumed extinct by the late 1800s.  It is a refreshing example of how we might conserve wildlife by doing just simple things such as reducing direct or incidental killing of them, and by limiting the modification or destruction of important habitats.

What kinds of research are you currently working on?
I am now doing broad ecological studies about how various marine species acquire resources to support growth, survival, and reproduction, and how population growth and distribution are affected by their successes and failures.  Many of these studies involve using transmitting tags in addition to direct behavioral observations.  I collaborate with other scientists to use molecular genetic methods to determine the relationships of individuals and the extent of movements of individuals among populations.  I also work with veterinarians, pathologists, and epidemiologists to understand how variation in the health of individuals affects their survival and reproduction, as well as the overall effects of how variation in individual health affects the whole population status and growth.

What different types of populations do you study?  Are their any connections that you can make from one population to another?
Since 1979, I have been conducting a long-term study about populations of northern elephant seals, California sea lions, and harbor seals on the Channel Islands in Southern California waters, a long-term study that I began in 1979.  I’m also studying marine mammals and seabirds in the Antarctic and Southern Ocean, ribbon seals in the Bering Sea, and whale sharks in the Maldives, the Philippines, and Western Australia.  The goals in several of these studies are to discover basic information on the habitats that are important to these poorly known species, as well as the variables, biological and non-biological, that affect them.  The use of tags and molecular genetics are the key tools for understanding how populations of each species interact, and how species (including humans) coexist while using common resources.

What types of field methods do you use to conduct this research?  What different types of tags are there? 
The first challenge in any of these studies is to find the animals.  I do this using a variety of boats, airplanes, helicopters and sometimes submersibles.  Once we find the animals, we have to determine what equipment is the most appropriate for collecting information about them.  Sometimes this winds up being just binoculars, cameras, and paper and pencil.  Other times, when we want to collect information when the animals disappear for long periods of time or when we can’t see them (when it’s dark or they dive) I use various kinds of small recording and transmitting tags.  There are several kinds of tags but most of them are based on small microprocessors that measure depth, salinity (saltiness), light, and temperature.  Some of these tags transmit data directly to us.

Are there any risks associated with tagging these animals? Does the tagging hurt or disturb the animals?
Working with wild animals is often dangerous so we have to develop, test, and apply methods that provide safe conditions and safety for us and for the animals that we study.  I have worked with various colleagues to develop tagging methods that do not harm the animals we are trying to learn about.  Sometimes we can work with animals in zoos or aquariums to the extent that these are compatible with the normal requirements of those institutions.  In some cases we can actually monitor the short and long term responses of animals to tagging whereas in others we just spend as much time as we can observing how animals respond to handling and tagging.  We also examine data that we recover from tags to help us monitor and understand any responses of animals to tagging.  We use all of that feedback to modify our techniques if needed in order to disturb the animals as little as possible.

Why is tagging an important aspect of your research?  Are there other methods that could give the same information?
Tags of various sorts are very important tools for discovering basic things about the lives of animals that are key to their conservation and management, and for establishing how subsequent studies should be planned and executed.  Certain kinds of tags allow us to clearly identify and monitor individuals and to examine the effects of age and sex on the behaviors, physical biology, foraging and reproduction.  In some cases, like whale sharks, we might be able to identify individuals by their body coloration and scarring patterns, but we still need some independent mark or tag to validate those photographic methods.  Some of the tags can also tell us where animals are and what they are doing when we cannot see them, which can be most of their lives \ in some species.

What research have you done with the whale sharks in the Maldives?  What research have you done with whale sharks elsewhere?  What conclusions has this research led you to?
I have been collaborating with the Maldives Whale Shark Research Programme to determine when and how often particular whale sharks appear near South Ari Atoll in the Maldives, as well as how quickly they grow.  I have also been attaching satellite-linked data recording and transmitting tags to these sharks to determine where these sharks are and what their foraging habitats are when they are not seen.  I have been conducting similar studies along the coasts of Kenya and Western Australia and in the Philippines. (For more about whale sharks in the Maldives, see what Adam Harman has to say!)

I’m also collecting small samples of skin to evaluate the relationships of whale shark groups among the Indian Ocean, Pacific Ocean, and Atlantic Ocean.  So far we’ve seen that whale sharks are continually mobile though we have not seen evidence for extensive migrations, and the genetics studies indicate that sharks move between groups and interbreed.  However, the evidence from the photographic tagging studies do indicate that whale sharks, especially males males, move into areas of the Maldives where they can be seen when they are a few years old (about 3 to 4 meters long).  Perhaps this constitutes immigration (moving into a population) though we still don’t know how far they were from the Maldives before they became visible.  Some of those sharks are seen in subsequent seasons for up to several years but then vanish when they are around 7 to 8 meters long.  This may constitute emigration (moving out of a population), but we do not know where any of those sharks go nor do we know where females live throughout their lives.  The use of telemetry and transmitting tags is a fundamental tool to allow us to discover those things.

Your research is so unique!  What advice would you give to a child interested in becoming involved in science as a career?
Expose yourself to as much educational (formal and informal) rigor as you can, read as much as you can of as many different kinds of literature.  Practice writing and rewriting and rewriting. Learn to be reasonably skeptical and constructively critical.  Explore.  Work in as many different jobs as time allows and learn how to maintain your integrity, even when others might be convinced that compromising it will result in material rewards.  Perhaps a bit heavy, but very important I think.  And, oh yeah, include music as a part of your every day life!

As a scientist how have you used creativity and your imagination?
I use it every day even when I not aware of it, though it does seem to be painful at times.  I don’t think being creative is easy, but that is why I think it is so rewarding in the end.  It changes you and you see everything a little differently and hopefully more clearly.   It also provokes more creative effort!  As a scientist you can watch things and imagine what you see might mean or how it might actually work but then the next step is to explore those imagined things rigorously to confirm or deny whether your imagination was realistic and reasonable or whether you need to look at things a bit differently to understand what they really mean.  This is essentially the scientific method.  Sometimes you need to start with pure wild imagination when looking at things that are little known, like whale sharks, and then move forward .  But when you know a little more about some things you can challenge or question your imaginations immediately to get on the path to truth.   This means that scientific thinking and scientists are not necessarily as stereotypically straitjacketed as many might claim.  Imagination is an important central element of our lives too.

Dr. Brent Stewart received both his Bachelor of Arts and Doctoral degree in Biology from the University of California Los Angeles, he also holds a Master of Science Degree in Ecology from California State University at San Diego, as well a Juris Doctorate from Boalt Hall School of Law, University of California at Berkeley with an emphasis in Constitutional, Administrative, and U.S. and International Environmental Law.  Dr. Stewart has studied the population biology, foraging and physiological ecology, and behavior of marine mammals, sea birds, and whale sharks for over 30 years.  His research has taken him all over the world, from Greenland to Africa, from California to Russia, and from the Antarctic’s Southern Ocean to China’s Yangtze River.  His research consists of comparative studies of marine vertebrates in order to understand what habitats are important to them, how they navigate and migrate over vast distances, how they hunt, reproduce, and interact, as well as how they respond to various anthropogenic changes in their habitats.  The overall objectives of his scientific studies are to contribute his findings to scientific literature and to education, conservation, and management authorities to promote science-based conservation of ocean life. 

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