Ocean Guilds

The great white shark and the Salmon shark are closely related — each part of what’s called a shark “guild.” Up next — a scientist talks about tracking the movements of shark guilds. Speaking with Randy Kochevar, a scientist with California’s Monterey Bay Aquarium.

Kochevar is principle investigator of TOPP — the Tagging of Pacific Pelagics project. It uses electronic tags to track the largest predators of the Pacific Ocean via satellite.

TOPP looks at what are called “guilds” of closely related animals. For example, rather than just tracking great white sharks, TOPP has looked at the mako, the thresher and the salmon shark — all part of the same shark guild. This approach has generated questions for Kochevar and his colleagues.

Kochevar: So how are they using the ocean in different ways? If they were using the ocean in exactly the same way, then they’d all be white sharks, or they’d all be salmon sharks, but they’re not, they’re different. So, what makes a salmon shark different from a white shark? How does it behave differently? How does it utilize the ocean differently? This becomes an interesting question, and it’s one that we can start to address.

And something remarkable became apparent in the case of the salmon-loving Salmon shark. Once thought to hover in the cold coastal waters of Alaska, these sharks were found to migrate large distances south, with several winding up far off the coast of Southern California.

Interview with Randy Kochevar

RK: My name is Dr. Randy Kochevar [KOH chee vur]. My title is science communications manager at the Monterey Bay Aquarium, and I’m also one of four principal investigators of the Tagging of Pacific Pelagics, or TOPP program.

ES: So tell me about TOPPS.

RK: The Tagging of Pacific Pelagics Research Program is one of several field projects that are under the umbrella of the Census of Marine Life. The Census of Marine Life is Envisioned as a 10-year long, billion dollar kind of a program designed to answer some very basic questions about the ocean — what lived there, what lives there now, and what will live there. And TOPP is one of the field programs designed to answer that second question — what lives in the oceans. And we’re taking what we call a top-down view of understanding life specifically in the North Pacific. And what we’re doing is that we’re trying to understand the movements of these marine mega-fauna, these big charismatic animals like whales and sharks and sea birds and sea turtles and sea lions, and things like that that travel across the ocean, across the North Pacific. They cover great distances. They’re feeding at the top of the food chain. So we’re just trying to understand where these animals go, and — more importantly — what are the factors that control those movements. We can think about questions like, where are the watering holes, to draw the analogy out to terrestrial eccosystems. Where are the breeding grounds, Where are the fertile valleys, where are the deserts, and what are the passage ways used to travel from place to place.

ES: What kind of information do you get from tagging these animals?

RK: The kind of information that we can get from tagging and tracking these animals is information about — where are the critical places in their worlds. You have to remember that we’re talking about a group of animals that are largely invisible. We might see them at the surface for a few brief minutes at one point on earth. Then we might see them half a year from then, half way around the world. But we really don’t have a sense of what were the things that were happening in between. What were they doing? Were they feeding? Where they breeding? Were they simply migrating? And where did they go? These are the kinds of really basic questions that, for most animals in the ocean, we don’t know the answers to. So, who cares? Why would we want to know these kinds of things. If we are to eventually protect these animals, and several of the animals that we’re talking about are either threatened or endangered — for example the leatherback sea turtles are critically endangered, they will be extinct in our lifetimes if we don’t do something quickly. But we really know very little about how they use the open ocean environment. So if we can start understanding where they go, what they do, what are the factors that control those movements, we may be able to, for example, predict where they go, and to be able to create management programs that will take into account where we know these animals are going, so that we can keep them from places where they’ll be in harm’s way.

ES: Why did you choose to study these particular animals, the apex predators?

RK: The reason that we decided to focus on the apex predators, on the big animals at the top of the food chain, is actually quite simple. If we were to ask our listeners to close their eyes — if they’re not driving of course — and picture the African Plain. They would be able to do that, they could picture where those animals go, and in fact if a scientist wanted to study the movements of animals across the African Plain, one way to do it would be to sit on the top of a mountain with a pair of binoculars, and you could watch, just the lions, or just the jaguars, or just the apex predators, we could watch those animals, because where they go is going to be driven by where their prey goes, the animals that are below them on the food chain. So we’re going to see the lions moving around following the zebras or following the antelope. And those animals are going to be moving in response to other environmental factors — like where’s the water, where’s the grass growing, where is their food. So, by just focussing on those animals at the top of the food chain, we can actually learn quite a lot about the functioning of the entire ecosystem below them.

ES: How is what you’re doing now different than when these animals have been studied in the past?

RK: Typically, what we have learned so far about animal migrations, has happened in a couple of different ways. One is, for example, we have fisherman who are living their lives out on the ocean — and some of these animals are commercially harvested. For example, the tunas that we’re studying are animals that have been commercially harvested since ancient Greek times. And so, fishers know very well where these animals are and where they move, because they’ve spent lifetimes following these animals across the oceans so that they can consistently catch them. So although you may not know where any one given individual animal goes, you know where the schools are going, because you’re following them around the ocean. In other cases, for example some of the whales, we actually know individual whales by markings on their flukes and on their fins. So we know that this particular whale was sighted off of Baja, and then it was sighted off of Monterey, CA, and then it was sighted off of Vancouver. And so we actually do have a sense of where that one individual whale went. But those examples are actually pretty few and far between. The TOPP program makes use of recent advances in technology where we have these little microcomputers that have the kind of processing power of a palmpilot. And we’re able to attach these little computers on to these animals. And they have sensors that are collecting data from the environment. And using those data, we can actually put together a picture of where this animal went and what its behavior was — how warm or cold was the water it was swimming through, how deep was it diving, and where on earth was it, what was its geographic location.

ES: Can you talk a bit about the different kinds of tags used?

RK: The TOPP program is making use of several different kinds of electronic tags to follow these animals around the ocean. I’ll try and briefly describe some of these different kinds of tags. One is called an archival tag, which is basically a set of sensors. There’s a sensor for temperature, there’s another sensor that measures pressure, there’s another sensor that measures the light levels. And in some cases, these archival tags are attached externally on the animal, and in other cases, they’re actually implanted surgically inside the animal so we can measure things like internal body temperature and learn more about the animal’s physiology. But these kinds of tags rely on the fact that the animals are either going to return to the same place, so that we can recover those tags or that the animals are going to be harvested. So these things work great, for example, in Albacore, because Albacore are heavily fished. So when we put tags on Albacore, we have a pretty good chance of getting that tag back and actually being able to download the data from the tag. Now in those cases where the animals aren’t harvested, where there’s a very low likelihood of getting that tag back, we use another kind of a tag called a pop-up satellite tag, and it has the same kind of sensors in it, but it’s mounted externally on the animal, and it’s attached with this corroding pin. and in a predetermined period of time, say after a year or a year and 1/2 or so, a current is sent through that pin, the tage is released from the animal, it floats to the surface, and then it actually telemeters the data back, using a satellite. So we get information back, automatically, telling us in general terms where they’ve been, and how that animal spent its time — what depths it’s been at, what kinds of temperatures its experienced. There are other types of tags that have been used in those cases where animals spend a great amount of time at the surface. Many people are probably familiar with GPS systems, global positioning systems. There are tags that make use of that technology. For example in sea birds, so that we know where the animal is in your real time, we can check every day and learn its position. And other tags that use a different satellite system, but can still estimate the position on the globe are also being used even with some marine animals, animals that live under water but that spend enough time at the surface so that that tage can actually talk to the satellites, and we can actually get a good solid location on that animal.

ES: Dumb question — why aren’t all the tags GPS tags?

RK: These tags are very, very expensive. The GPS tags are actually still being developed, and the technologies are still being perfected for those tags. Whereas for some of the other tag systems, they’ve actually been in use longer. It should be said that one of the decisions that we made early on in TOPP was we didn’t want to invest millions of dollars and years and years in time and effort developing new tags. We wanted to instead kind of hit the ground running, use the tags that have already proven to be reliable, tag animals that we know we can tag, and really focus on trying to answer some of the bigger questions about how these animals are using the ocean, and what’s controlling their movements.

ES: Can you give me an overview of the project — who, what, and when?

RK: The TOPP program officially kicked off back in November of 2000. That was when we had our first meeting where we brought together a group of scientists — biologists, oceanographers, computer scientists, educators, a whole large group of people came together to start talking about whether it might really be possible set up a huge collaborative program like the TOPP program. Many of the people who are involved in the TOPP program have been doing this kind of research for years and years. But they’ve been focused on a limited group of animals. Nobody has ever tried to put together a collaborative effort where we would be tagging 20-somithing different species, over 5000 animals. We’re now just, in 2003, launching into phase 2 of the program, where we’re really building the infrastructure. We’ve done a couple of years of planning now. It’s time to start actually building the infrastructure, building the computer systems to do all of the work. We will also start ramping up the fieldwork. We have 100-150 tags in the ocean right now through the TOPP program. By the end of the fieldwork, which is sometime around 2007 or so, we expect to have about 5000 tags in the water. And then by the time we get through getting all the data back, doing the analysis, publishing the papers, and all that, we’re looking at a program that’s about 10 years long. So, hopefully, by 2010, we’ll be wrapping things up. Some of the other key investigators on this, Dr. Barbara Block from Stanford University, a professor of marine biology at Hopkins Marine Station. She is the leader of the program. She has spent years and years tagging open ocean fishes, primarily tunas, billfishes, sharks. Dr. Dan Costa, is the other lead investigator, Dan is from U.C. Santa Cruz. And he has spent his career tagging marine mammals — elephant seals, sea lions, doing work in Antarctica with other pinnipeds, seals and sea lions. Then we have Stephen Bograd at NOAA. Stephen is a physical oceanographer. And myself at Monterey Bay Aquarium, and I’m working on the education outreach programs for TOPP. One of the other organizations that can’t I can’t go without mentioning are those people who have provided funding for this. The Sloan Foundatation is the group that originally had the vision of the Census of Marine Life, and they have provided us now with two different grants to keep this program going. We’ve also received generous funding from the Packard Foundation, and we’ve received some government funding as well from the Office of Navel Research. And we’re in the process of, constantly, submitting other grant proposals both to private foundations as well as to federal government agencies.

ES: Isn’t TOPP part of a bigger project – The Census of Marine Life?

RK: Yes, that’s correct, the TOPP program is one of — I think there’s seven or eight — a handful of pilot programs of which TOPP is one.

ES: Let’s talk about one of the successes of the project.

RK: Last summer, one of the big successes on the TOPP program was when a group of researchers went up to Alaska, and they were tagging a group of animals called salmon shark. Salmon sharks are not as widely known as their cousins, white sharks. But they are closely related to them — they’re in this lamnid shark group. These are the big, predatory sharks that are warm-blooded, they keep their internal body temperature above that of the surrounding water. They can swim very fast and cover very great distances. And they also eat very big animals. For example, white sharks will feed on things like elephant seals and sea lions. And the salmon sharks are so-named, not because they look like salmon, but because they feed on salmon up in the gulf of Alaska. So the TOPP researchers went up there and were successful in applying these spot tags, these satellite position only tags, onto salmon sharks and we started tracking these things. Now people thought that, because they’re feeding on salmon, these salmon sharks are probably more of a coastal animal. But in fact it turns out that these sharks are swimming in the open oceans. We have several individuals that took off straight from the Gulf of Alaska, headed straight south towards Monterey, and in one case towards Hawaii. These are animals that are really covering tremendous distances. This was a new and unexpected finding for these animals. Another example of a really exciting development in the TOPP program was — there was this crazy idea, I had said previously that we were trying to avoid working with animals that had never been tagged before. But there were a couple of researchers who were really excited about the idea of being able to tag and track Humboldt squid, which are these big, commercially fished squid. A big Humboldt squid can be five or six feet long, it can weigh 60 to 80 pounds — this is a big animal. So, one of the researchers said that he was going to go down to the Gulf of California and do some tagging. And if we could provide him with one of these electronic tags he would put it on the animal. He was successful in doing that. And we actually got back the first ever satellite tag information, or archival tag information about the movements of one of these big Humboldt squid. So we started learning about where it spends its time during the day and at night, and how quickly it travels and so on. So this is just a glimpse of the kind of learning, I think, that we’re going to be getting out of this program. And as we start looking at greater and greater numbers of animals, and overlaying those data, with things like — what is the sea surface temperature, what are the winds doing, what is the sea surface height — these other physical oceanographic factors, we can start understanding not only more about where the animals go and what they do, but also about what are the factor they’re responding to? What is the ocean like around them that they’re living in.

One of the decisions that we made in the TOPP program about the way we wanted to approach it was to look at what we call guilds of different animals. So, for example, instead of just tagging pacific bluefin tuna, we are going to be tagging bluefin tuna, yellow fin tuna, and albacore. What makes that interesting that these are animals that are closely related but that are different. And when you see that you have different species of animal that are similar, it means that sommehow they’re using the ocean in different ways, there was some reason that these closely related animals over the course of evolutionary time started looking different and behaving different. So they’re finding different ways of using the ocean, different niches if you will. So by tagging groups of closely related animals, we can learn more about different ways of using the open ocean. So how does this relate to salmon sharks, why choose salmon sharks? Well salmon sharks are in this group of lamnid sharks. The lamnid sharks, as a group, are the really powerful, predatory sharks that feed, often times on large animals including mammals, so the great white shark, the mako, the salmon shark, the thresher shark, these are all in this lamnid shark group. So this is another example of a guild of animals, where we know that, for example, the white shark, and the salmon shark, are closely related animals. So how are they using the ocean in different ways? If they were using the ocean in exactly the same way, then they’d all be white sharks, or they’d all be salmon sharks, but they’re not, they’re different. So, what makes a salmon shark different from a white shark? How does it behave differently? How does it utilize the ocean differently? This becomes an interesting question, and one that we can start to address.

ES: How do the findings of

RK: I guess the one other thing that would be nice, is if our listeners are interested in learning more about this program, they’re certainly welcome to go to www.toppcensus.org, or they can go to the Census of Marine Life homepage, which I believe is www.coml.org . And as we move forward with this program, we’ll be developing more, new things that they’ll be able to see on the website. For example, they’ll actually be able to see the data, they’ll be able to follow the animals as they move across the ocean. These are some of the kinds of things that we’re working on right now.

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