Looking below the surface with whale DNA
Biologist Stephen Palumbi use the science of genetics to help study and protect whales.
Salazar: I’ve heard you say that, in your research, you use the science of genetics try to find out about how whales really do live their lives these days. And then you use that information to help conserve and protect their populations into the future. Please explain more about that.
Palumbi: We look at the genetics of whales. Whales are just like any other creature, right? They’ve got all of their DNA and all of their cells, and for our purposes, we can get a sample of a whale’s entire genome just by taking a little scratch off of the surface of its skin.
Just by getting a few skin cells off this animal, we can then begin to do all of the things that modern genomics technology lets us do to understand that individual, or the population that that individual comes from, or the species of that individual.
So, to give you an idea of the sort of things that we can ask, we can tell the difference between whale species morphologically, how they behave and what they look like. There are some whale samples useful for that. Those whale samples are samples that we find in whale meat markets around the world. They’re in little styrofoam packages with cellophane on top of them. And all of the normal ways that we would use to identify a whale species, all of the clues … they’re gone. But that meat still has its DNA. Even if its in a can, or if it’s dried, or if it’s made into whale jerky, we have access to the DNA.
By looking at the DNA of the samples, we can see what whales are for sale in different markets around the world. Knowing that tells us a great deal about the risks that whales are facing out in the open ocean, and the risks that they are encountering in commercial markets that are still open to them.
Salazar: What did your research tell you about the kinds of whale meat sold?
Palumbi: What we were able to discover when we looked at the genetics of whale meat markets is that there’s a wide variety of whale species available on those markets.
It turns out that the number of whale species that are really supposed to be for sale, commercially in the world, is quite small. Countries have to give themselves permits to hunt whales for scientific research, and then under certain circumstances they can turn those scientifically hunted whales back to commercial uses. And so, we have a record of all of the scientific permits issued, and that record should match the kinds of species that we find on the whale meat market.
When we started this research, along with Scott Baker, a former post–doc of mine in the early 1990s, what we found was a wide number of species were in those markets that were not represented in those scientific permits, meaning that whales were subjected to hunting under the umbrella of these scientific permits that shouldn’t have been hunted.
In the subsequent years, that record of illicit whaling has gotten better, over time. The number of species that shouldn’t be on the market has dropped. But, at the same time, what we find is that the whale meat market has gotten more and more of other kinds of whales in it; dolphins, porpoises, the so–called “beaked” whales. And these represent another problem.
These animals don’t feed like the big baleen whale. These animals, the dolphins and porpoises, feed on coastal fish and invertebrates, and they can actually bioaccumulate toxins, like heavy metals and dioxin. In some circumstances, those dolphin and porpoises have been known to actually be toxic to human consumption. And here on the whale meat market, we discover that products that really are dolphin or porpoise are labeled as whale, and those products are heavily contaminated with heavy metals and dioxins and coastal contaminants.
So, our next phase in this research was to point out that, in fact, mislabeling of these products, mislabeling dolphin and porpoise as whale, was a health risk to people if they actually got a hold of a toxic piece of dolphin meat and thought it was whale meat and consumed it.
Salazar: How did the industry react to these findings?
Palumbi: The response to this research has been, I guess, all of the stages that you can imagine of denial. And over the years, what’s happened is that gradually there’s been a shift towards the acceptance that the technology is correct, that the genetic data are powerful, that the answers that the genetics provides are actually something that you can rely on. And over that period of time, more and more people have pointed to the need to curtail, essentially, illicit whaling and to try to establish what is essentially a fair marketplace for whales.
It’s not our position whether people should or shouldn’t eat whales. It’s our position that if commercial whaling is going to be allowed, it must follow internationally recognized and sanctioned regulations. There shouldn’t be any cheating. Our attempt to gather data has been to try to make the marketplace as fair and “cheating–free” as possible.
So along those lines, we’re simply trying to get various countries from around the world to agree to an international DNA database that would identify all whales taken for commercial or scientific purposes and make the genetic data broadly available around the world. Because right now, the genetic technology has gotten to the point where we can identify not only the species of whale on the whale meat market, but if we really wanted to, we could actually identify the individual whale.
By having a DNA registry of all individual whales that have ever been taken by scientific or commercial permit, we would be able to know, for example, if we went to a whale meat market and took a sample, and looked at the genetic identity of that sample, at the individual level, we should be able to find that individual’s genotype on this international registry, know when it was hunted, where it was taken, and why, and by who. And if we had that sort of information, the international whale market, as it were, would be much more highly regulated and transparent. Well, we’re far from that right now. We’re facing a lot of opposition to that idea.
We hope that, over the next couple of years, that opposition begins to see that this is not a threat to any kind of scientific whaling industry. It’s actually a way to make the industry more transparent and make it accountable to the regulations.
Now people don’t want to hear scientists saying things like that, mind you. We’re supposed to just do our science and go home. But we feel like it’s important to not only do the science in as effective and rigorous way that we possibly can, but also point out the ability of science to make public policy easier and more successful.
Salazar: Your research also found that humpback whale populations were much higher in the past than was estimated using historical records. How does something as small as DNA tell us that before commerical whaling, the oceans once held 1.5 million humpback whales?
Palumbi: The other way that we use genetics is to try to paint a picture of the past history of whales. We all know that whales were once very abundant, and that whaling around the world reduced their numbers enormously. But what we don’t know, really, is how many whales there were before whaling. And the reason that we don’t really know that is because the records that were kept were kept by the whalers themselves. Sometimes they’re excellent. But sometimes they’re not. And it’s nice to have an independent estimate of what the history of these populations was like. A French explorer named de La Pérouse sailed into Monterey Bay, just here near the Hopkins Marine Station, in the late 1700s, and wrote that he was just appalled by the incredible stench of the bay because the breath of all of the humpback whales around it made the bay air stink of their nasty, smelly breath.
So, we knew that there were a lot of whales in the past. How many, is the question. So, we have really pioneered the use of looking at genetics to answer that question. And here’s the way that it works.
All populations have some genetic variability. But a small population becomes inbred and that genetic variability gets reduced. A big population doesn’t have that much inbreeding and the genetic variation in it actually remains high. So the level of genetic variability in a population tells us how big that population has been in the past.
Now we have to calibrate that by understanding things like the mutation rate, and we have to understand the mutation time. It’s a complicated set of calculations to make.
But the basic principle is that a bigger population, which has been bigger for a longer time, has more genetic variation in it than a smaller population. So then, what we do is we go out and we sample a lot of whales in a population. We get these samples by taking small biopsies, small skin samples of free–ranging whales or sometime we have whales that slough off skin when they breach.
Other times, they are cast up on the beach, and we get a sample that way. We take this sample of the population and calculate the total amount of genetic diversity in that population. And from that calculation of the amount of genetic diversity, we can back calculate how big the population has generally been.
When we do that, for baleen whales, we discoverer much to our enormous surprise that there’s way too much genetic variation in these whales than there should be if the conventional wisdom of how many whales there were before whaling is really true. If that conventional wisdom were true, we’d have a very low amount of genetic diversity in baleen whales. But we have a genetic diversity that sometimes three, sometimes five, sometimes as much as ten times higher than we’d expect on that basis.
And so that leads us to suspect, very strongly, that whale populations in the past were far higher than they are now, maybe up to three, five, or ten times higher.
Salazar: What does the future look like for whales?
Palumbi: Well, I think the future for whales is quite hopeful, but there’s some serious, serious problems that are out there. The hopeful ones are that there are some populations of whales that are coming back; humpback whales, grey whales along the west coast of the United States. These are populations that are returning to at least something like their former numbers. They still have a long way to go, but in addition to what we’ve discovered by letting them begin to grow, that they are a far better industry for whale watching than they ever were for whale hunting. Right now, the value of whales just for tourism and for whale watching industries is about a billion dollars a year, around the world. So, it represents a totally different way of the world, essentially, generating income from whales than before.
So that’s a great sign. Whales actually can begin to come back and that a healthy whale population is actually valuable to lots of different people.
But there are problems. Although the eastern grey whale has been growing in numbers, the western population is in terrible trouble. It’s estimated to be less than 125 individuals left in that population. They have the very unfortunate luck of wanting to feed right in the middle of gas and oil development off the coast of Russia. And they swim sort of along the Asian coast on their way to breeding grounds, which, right now, are undiscovered, and completely unknown. So this is a population that is under enormous threat and is not growing. It requires every effort possible to keep its ecological future bright.
The same is true of right whales in the North Atlantic along the east coast of the United States. There have been less than 300 animals in that population for as long as anybody can remember. It’s not a growing population. These animals like to take naps in shipping corridors, and they get hit by ships as they go by. They’re not reproducing very quickly, and the population is not growing.
So, in general, whale populations have the amazing benefit of a relatively strong and well–organized group, the International Whaling Commission, that regulates their hunting. And that group has really tried to bring all the whale populations in the world back up over the last 20, 25 years. Unfortunately, their efforts may be a little too late for some whale populations that are really not responding. And those are the ones that we really have to make sure will never get into a whale meat market, never get into a situation where their commercial value is allowed to trump their ecological value, and into a situation where we stop protecting them.
Salazar: Thanks for taking time out to speak with us. Is there anything else you’d like to share with the public today?
Palumbi: Thanks for the questions. A final thing to say is that people have been fascinated by whales for a very long time, for centuries. We’re trying to ask questions within a new scientific technology… in this case genetics. But it could be acoustics, or it could be toxins. When we apply these new scientific methods to whales, we always find out something extraordinary and something really important. So hopefully, we’ll continue to do that with whales and get them to the point where we know how to protect them into the future.
