MS. DIANE REHMThanks for joining us, I'm Diane Rehm. Sharks are an ancient fish dating back some 400 million years. Humans have both worshiped and feared them throughout history. Today some species are threatened by overfishing, finning and the inability to reproduce quickly. Washington Post environmental reporter, Juliet Eilperin, traveled the globe to observe sharks in their natural habitat. Her new book is titled "Demon Fish," but it's really an argument for protecting their survival.

MS. DIANE REHMJuliet Eilperin joins me in the studio. You can join us as well, 800-433-8850, send us your email to drshow@wamu.org, feel free to join us on Facebook or Twitter. Good morning to you, Juliet, it's good to see you.

MS. JULIET EILPERINIt's fantastic to be here.

REHMAnd it's good to see you thinking about what you've been going through this past year.

EILPERINExactly. I think it's really important. I love doing daily journalism, but one of the great things about writing a book is you can pull back and kind of put what you've observed in context and that's one of the great things, to kind of put everything together and get a sense of what exactly is going on in the environment.

REHMTell us what your mother said about your writing this book, Juliet?

EILPERINI worked on this book for a few years and about a year into writing the book, my mother said, you're not actually swimming with sharks, are you? That's not possible. And I thought it was a fantastic commentary on maternal denial that not only did she really not accept it, but even after I told her that, yes, I was swimming with sharks, I think she was able to put it out of her head for the rest of the duration of my book writing.

REHMYou know, when I saw the title of your book, I thought to myself, are sharks fish?

EILPERINYou know, a lot of people don't know that because in some ways, they might think that they are more like dolphins or whales and our marine mammals.

REHMExactly.

EILPERINBut in fact, they're cartilaginous fish. They're different from other fish in that a lot of fish have bony skeletons and their skeletons are made out of cartilage, but yes, they're actually fish. But you're right, it's not what comes to mind.

REHMYou could have chosen anything about which to write. How come sharks?

EILPERINI wanted to write a book about the oceans because it's one of the most interesting things I cover. There's such incredible science going on, we're learning more than ever before and we're getting a sense of how we're affecting the ocean. And in some ways, it's more optimistic than writing about climate change and some of the other things I cover, so I wanted to do that.

EILPERINAnd then I talked to a lot of people and came to the conclusion that sharks would be an incredibly compelling way to that tale, that people have -- a lot of people have connections with sharks in a way that they don't with other things in the oceans, something like a coral reef is abstract or, you know, certainly a sea urchin. And so by writing the sharks, you're already tapping into people's natural interest in the ocean, but you get to do it in a thrilling way.

REHMNatural interest, but fear, big time.

EILPERINYeah, absolutely. People have this primordial fear of sharks. There's a good reason why we're scared because obviously, they're one of the few things that cannot only eat us, but launch surprise strikes against us. I think everyone has this fear that you get into the water and you may not see it coming, but a shark's going to come after you and so it propels this incredible terror in a way that very few other animals will.

REHMAnd surely the movie "Jaws" propelled that fear.

EILPERINThat was a seminal turning point, I think, in the -- in not only the American psyche, but frankly, people everywhere. I've -- there are so many people, including marine biologists I've talked to, who as children saw "Jaws" and wouldn't get back in the ocean for a while, wouldn't even get into a swimming pool.

REHMReally.

EILPERINSo there's no question that Peter Benchley, who eventually -- you know, who did become one of the most prominent ocean conversationalists in the country, along with his wife, Wendy, really started by scaring the bejeezus out of all of us.

REHMYou know, my daughter, who is now 47, had already seen the movie when she was, I don't know, 18, 19 and she said, Mom, you've got to see it. And I said, I'm really reluctant to see it. She took me and she held my hand in order to watch that movie. But, you know, you write that sharks have always fascinated human beings.

EILPERINYeah, one of the most interesting things that I learned while researching the book was how many islands societies had entire faith traditions that were constructed around sharks. I mean, they had a much closer connection to the sea and they thought, in some ways, that sharks were their ancestors or could help mete out justice to the neighbor who you didn't like or protect you if you were going out in a storm or determine how many fish you brought in.

EILPERINSo it's really incredible how, you know, we're -- and we're coming new to this. While we might think that we've only focused on "Jaws" and sharks since the mid '70s, it goes back hundreds and hundreds of years.

REHMJuliet, you said you had wanted to tell kind of a good news story, but for sharks, it's a mixed news story.

EILPERINAbsolutely. What we're looking at, by the best estimates, is a third of sharks and their closest relatives, rays, are in danger of extinction, so there's no question that they're in trouble from a few different factors, but that said, there's absolutely a chance for them to continue to survive the way they have for hundreds of millions of years. And, in fact, we have a stake in helping them survive and so I think that's one of the things I'm trying to show, that in fact, by protecting sharks, we can help protect ourselves.

REHMWhy don't you read for us from the start of the book?

EILPERINOkay. So what I'm starting with is my first experience with sharks. "The sharks are almost glowing as they pass by, gentling nudging each other as they jostle for the bloody pieces of barracuda that the ichthyologist, Samuel Sonny H. Gruber, has thrown in the sea minutes before.

EILPERINTheir white-ish underbellies reflect the beaming Caribbean sun above. They're shimmering even as their steel grey upper bodies dull the light and provide them with a measure of camouflage. The pearly glow and stealth of these creatures confirm what I have long suspected. Sharks operate in a separate universe.

EILPERINThey glide, this lemon sharks, Caribbean reef sharks, blacknose sharks and nurse sharks. But unlike the pretty tropical fish beside them, which travel in neat, compact schools, these sharks swoop in from all directions. They display no attempt at coordination. Each one is out for itself.

EILPERINBefore I entered the water, a researcher warns me that I should rely on peripheral vision to make sure I can sense whether shark is approaching me from the side. Unlike a character in the movies, I cannot scan the surface of -- for that telltale fin that juts out right before cinematic climax. Shark points appear from array of angles, making such clear distinctions impossible.

EILPERINWhile I'm no expert in scuba maneuvers, I do my best to keep moving in this rapidly shifting underwater feeding frenzy, so as not to collide with one of the sharks by accident. I am more alert than a highway driver checking her blind spot while cruising at 75 miles per hour. It is as if I have crashed an amazing, bizarre party with several friends and need to be on my best behavior at all times for fear of offending our intriguing but menacing hosts."

REHMAnd they're feasting on barracuda and you're right there with them. Whoa.

EILPERINExactly. So luckily, I realized that they were more interested in the barracuda than me, but that really was this moment, particularly when you think that they were coming from all over, it's one of these places where sharks are doing better and so you really feel like, at any moment, you're facing down your primordial enemy.

REHMDid you have fear?

EILPERINI did, absolutely, you know, particularly my first time in the water and then a couple of other times after that. You know, there is something instinctual that takes over. It's almost as if we're programmed to be scared of them for our own survival, but what was amazing, even that first time and this was in 2005, the first time I jumped in the water, is that after a minute or two, I saw how beautiful they were. I really was struck by the gorgeous line of their bodies and how they moved through, like, the water like a torpedo and -- and it really hooked me.

REHMAnd had a glow from the bottom that you describe.

EILPERINYeah, I mean, there's way that, you know, that sunlight is hitting them and that you're seeing them from beneath, which is totally different from how you're often -- you know, the idea of seeing either the fin out of the water or you on the surface looking down, so there was just something, you know, almost heavenly about it.

REHMSo now we come to this question about shark kill.

EILPERINAbsolutely.

REHMAnd how frequently it's being done and the reasons why.

EILPERINThere are a few different reasons why sharks are being killed in massive numbers worldwide, so one of the ways is through the targeting of their fins. Sharks fin soup is a delicacy in Asia, it's popular not only in China, but throughout Asia, particularly in countries where there are large Chinese populations and it's really a prestige dish.

EILPERINThe idea is you serve it at a wedding or a business meal to show that you're willing to pay enough money to have sharks fin soup and also, that you have managed to conquer this beast that we hate. And in that context, you have something -- you know, scientists estimate up to 73 million sharks a year are caught just to supply the shark fin.

REHMSeventy-three million?

EILPERINMillion sharks and by contrast, sharks kill between four and five people worldwide on average, so that's four or five people die each year from shark strikes and up to 73 million sharks are killed a year just for the sharks fin soup.

REHMHave you tasted it?

EILPERINI did. I tasted it in Hong Kong. I thought, you can't write about this without tasting it and what's fascinating is that for the -- the fin is -- they take these really tiny needles out, which become like small, small noodles and they're tasteless. It's the texture and just the idea that it's in there that matters. But the taste for the soup comes from chicken and pork. If you didn't have all the other flavorings they threw in there, you would be tasting nothing.

REHMThe other reason that they're being killed in such large numbers?

EILPERINThe other primary reason why sharks are being killed is through accidental catch, bycatch, is what they call it. So basically, fishing vessels are targeting other large predators, like tuna and swordfish, but they lay out those lines and put in hooks that catch sharks just as much as tuna or swordfish that are going after the fish that's attached to the hook and that certainly kills millions of sharks each year and because they often throw those bodies overboard or they simply take them and sell them, but don't report it, we actually are unclear about how many sharks are killed each year for that.

REHMJuliet Eilperin, she's national environmental reporter for The Washington Post. Her new book is all about sharks. Short break, right back.

REHMAnd if you've just joined us, Juliet Eilperin is with me. She's national environmental reporter for The Washington Post. She has a new book out, it's titled "Demon Fish: Travels Through the Hidden World of Sharks." And she doesn't mean traveling on the surface. She did get in the water with a number of different species of sharks, some of which I gather could have been a bit frightening.

REHMHere's a question from Jonathan who says, "Were the sharks bigger 200 million years ago? How do we know they preexisted dinosaurs when Sharks have no bone and cartilage? Does not that leave us the same type of fossils?"

EILPERINJonathan, that's an excellent question. The fact is that we do have, for example, fossilized teeth and certain other fossils that come from sharks. And it's, in fact, how we know that there used to be sharks in Montana because that was covered with oceans, you know, a millennia ago, so -- but you -- but he's right in that it's harder to reconstruct these things.

EILPERINThey have been able to, you know, find some fossils that give them guides and the answer is the predecessor, the ancestor of the Great White, for example, was enormous. And the scientists have even been able to calculate that it had the most powerful bite on earth, multiple times the bite of say an African lion, so we really do have some clues, but it's difficult because of the fact that they have a cartilage and a skeleton.

REHMHere's a question from Laura in Bethesda about something she heard with Ira Flatow on "Science Friday" on NPR. She says, "Can the guest comment on the observations of Australian scientists noting that sharks like AC/DC music?"

EILPERINRight, this is a thing that just got a lot of press. The idea's apparently "Back In Black" and, you know, "You Shook Me All Night Long" are things that -- what's interesting is it got reported different ways. The tour operator both said it brought shocks to the boat and it also appeared to calm them down somewhat, so, you know, clearly that's anecdotal, but it will be interesting to see whether that there's that and whether frankly other tour boat operators -- I've been out on a charter fishing boat with someone who went for catching sharks.

EILPERINHe actually plays a song which has to do with South Beach and, you know, so I think different tour operators have different strategies and I think they do whatever works for them.

REHMTalk about the practice of finning. I think you have a section in the book...

EILPERINYes.

REHM...on that. Do you want to read that for us?

EILPERINSure. (unintelligible). So this takes place when I travel to Hong Kong and was able to go inside a shark fin auction, which is something that's -- which is not open to the public and is a little hard to get into. "Each kind of auctioneer has a style. There's the robust cattle auctioneer who spits out numbers in a bold singsong voice that determines where animals go to be bred or to be slaughtered. The elegant estate auctioneer, who's rich, mellifluous (laugh) tone entices art and furniture collectors to fork over their savings.

EILPERINAnd then there's Charlie Lim. A spectacled wiry man in his early 50's. Lim sports a short-sleeved button-down shirt and a modified bowl cut that lets his straight black bangs fall neatly across his forehead, standing in front of the sort of shiny white boards that appear in classrooms and corporate conference rooms across the globe. He doesn't talk much as he auctions off his wares. Instead, he shakes an abacus in short regular bursts. Much of the time, the clicking of the beads is the loudest sound in the room.

EILPERINLim is a shark fin trader. More precisely, he's the secretary of Hong Kong's Shark Fin and Marine Products Association. And at the moment, he's standing in a nondescript auction house, whose spare white décor evokes a Chelsea art gallery. But when the auction begins, the buyers crowd around Lim in a semicircle jostling for a look at the gray triangular fins displayed across the floor.

EILPERINA shark fin auction is as fast as it is secretive. By the time Lim takes his position at the front of the room, one of his assistants has already marked on the board behind him in a bright red felt tip pen which sorts of fins are being auctioned in any given lot. As soon as the men dump the contents of a burlap bag on the floor, the bidding begins. Any interested buyer must approach Lim and punch his suggested price into a single device that only the auctioneer and his assistant can see.

EILPERINThe bidders must make a calculated guess about what price will prevail, rather than compete with each other openly for a given bag of fins. Within two minutes, the lot is sold and the winning price per kilo is duly noted on the board. Lim's assistants sweep the pile back into its bag using a dustpan to gather any errant fins that might have escaped to the side. Another bag containing the first dorsal, pectorals and lower lobe of the caudal fins that are the most valuable is dumped on the floor and the cycle begins again.

EILPERINThe group of men gathered here, and it's all men, are experienced traitors who hear about these auctions through word of mouth. There is no downtime, no chitchat. In fact, there aren't even chairs for them to sit on during an auction. Given the fast pace of shark fin sales, they must be prepared to bid without hesitation. The buyers show no emotion during the entire process. This isn't fine art they plan to furnish their homes with or livestock that they will devote months to raising, it is a heap of desiccated objects they will seek to transfer to someone else as soon as they acquire it.

EILPERINLim does make a few remarks in Cantonese about the fins before his feet, but it's not the sort of chatter most auctioneers use to boast about the price of a given lot. He's not saying, take a look at these great beauties or anything to that effect. Sometimes he indicates the species that's collected in a given bag, blacktip, hammerhead or blue shark, but a shark fin auction is not really about salesmanship, it's about moving product."

REHMTell me about the importance of those fins to the sharks.

EILPERINThey're essential. They can't survive without them. So what will happen is that the fishing vessel will pull up sharks, which it's caught in a number of ways, slice off the fins and then, they'll make the decision often to dump the bodies overboard because it's cheaper for them to store just the fins that don't take up that much space and leave the body in the ocean, but at that point, the shark will die because it can't survive without them.

REHMIt cannot navigate.

EILPERINAbsolutely. And it also needs to keep moving. One of the interesting things I found while writing the book is, you know, people think that sharks are so scary because they're always moving and their mouths are open and that's because they don't have the same kind of swim bladder that other fish have. And so for them, with few exceptions, they need to keep moving so that the water can wash over their gills and provide them with the oxygen they need. So if they can't move, then they're not getting the oxygen they need to survive.

REHMNow, what about the outlawing of taking of those fins?

EILPERINWhat we're really seeing, which is very interesting, is the push to do that in a number of different ways. And right now, we're in the midst of a push for shark fin bans like we've never seen. So in the Pacific Northwest, there is a huge drive to outlaw the sale, possession or trade of shark fins. Washington has already enacted a law on this, so they did that last month.

EILPERINOregon has passed the law in both Houses and it's awaiting the governor's signature. And most significantly, in California, which has two of the largest Chinese food markets outside of Asia in San Francisco and Los Angeles, the California State Assembly passed by an overwhelming vote a ban on the possession, sale and trade of shark fins and it's likely to pass the Senate within the next few weeks and get signed by the governor.

REHMBut what about worldwide?

EILPERINWorldwide, it's a mixed bag. One thing you are seeing and the United States has done this, some other countries have done this, is move to insist that people who fish for sharks land them with their fins attached. That way, it at least cuts down the incentive to purely target them for their fins.

REHMBut why would they want them?

EILPERINWell, you can sell shark meat in various different instances and so there are certain fisheries where, yeah, they're used for fish and chips in England, they're sold in Germany and elsewhere. There's not that big a market for sharks here, but there...

EILPERINSeventy-three million.

EILPERINRight, but -- so part of the idea is you're going to cut down the economic incentive and, you know, maybe people will still continue to hunt some sharks, but they'll have fewer of them. So for example, Obama signed in a law that passed both the House and Senate by wide margins late last year in December that did mandate landing sharks with fins attached and Chile has already passed it in one chamber and may pass it as soon as today or later in the week.

REHMWhen you think about where the 73 million have been caught...

EILPERINRight.

REHM...or grabbed for fins, primarily where has that been?

EILPERINWell, actually, it's worldwide. I mean, that's one of the things. They go where the sharks are, so sometimes they're doing it off Costa Rica, where there are incredible congregations of hammerheads. There are times that they're doing it in Indonesia and Papua New Guinea, so, you know, because there are all sorts of different, you know, species of sharks, but many of them are ocean going and travel across borders, across ocean basins and so some -- you know, they can target them whether it's (word?) or here.

EILPERINWhile the trade is driven by Asia, there are Spanish fishermen who are going after them, there're, you know, again local villagers in small island nations that target them.

REHMAnd how long does it take them to repopulate?

EILPERINWell, that's an excellent question. It takes quite a long time. Sharks mature sexually much later than other and many other both fish and mammal -- marine mammals and then they often don't have as many young, so some, for example, might have one or two pups and, for example, the spiny dogfish has one of the longest gestation periods. It takes something like at least a year and a half, it might even be as much as two years, to produce a pup. And having been pregnant, I can say I wouldn't want to be pregnant for that long and you're not going to produce that many offspring if that's how long it takes to produce one.

REHMAnd do fishermen go after these pups as well as the full-grown sharks?

EILPERINWhat they actually go after are the females. That's the key thing. Females are often targeted. They can -- in some cases, they're larger. Certainly when they're pregnant, they're bigger. And so what happens is they're wiping out the part of the population that's most essential for reproducing.

REHMHere's an email from Barbara in Chevy Chase. She says, "I've been reading Laura Hillenbrand's book 'Unbroken,' the story of survival in the Pacific theatre of World War II.' The first part of the book focuses on the dangers of the air campaign and the threat that sharks posed to airmen whose planes crashed and to other servicemen who ended up stranded in the Pacific.

REHMThe waters seemed to have been teaming with sharks. My father, who served in the Pacific, also talked of how prevalent they were. Were there greater numbers of sharks in the Pacific in the '40s? What's happened to these populations?"

EILPERINThere were greater numbers of sharks without question and what we've seen really since that point is an incredible decline. In some cases, some shark species have declined by as much as 90 percent, even 99 percent in some cases. In some, it's been closer to 60 to 70 percent, but there's no question that there are fewer sharks swimming both in the Pacific and elsewhere as a result of the fishing pressures that we've seen.

REHMSo why should we be upset?

EILPERINOne of the most legitimate reasons we should want to keep sharks around, even though they scare us is because as one of the top predators in the sea, one of the apex predators, they keep midlevel predators in check. And it's really just a question of maintaining the same kind of balance we see on land, whether you're talking about lions and tigers in the African Savanna or wolves in Yellowstone. A whole host of other species are healthier if you have sharks taking out the weak in the ocean as well as the midlevel predators that can get out of control if they're not around.

REHMJuliet Eilperin, her new book is titled "Demon Fish: Travels Through the Hidden World of Sharks." And you're listening to "The Diane Rehm Show." The other day, I saw photographs of mounds and mounds of jelly fish on shore somewhere in this country and that very point was made that you're wiping out some species of fish who would ordinarily devour some of these other species that devour the jelly fish and hence the jelly fish are reproducing in greater numbers.

EILPERINIt's true. It's what scientists call fishing down the food chain. And one of the things that -- you know, one of, again, the reasons we might want to care about it is there are scientists including Pete Peterson, a marine biologist in North Carolina, who's pointed out in a paper that was published a few years ago that what it ends up doing is when you have the explosion of some of those midlevel predators, it wipes out, say, oysters and clams and, in fact -- and scallops. These are things that we actually like to eat and they're also things that fishermen depend on for their economic livelihood, so there really are real world consequences to this.

REHMSo man has an obsession with sharks one way or another.

EILPERINRight. I mean, so, you know, you really see it -- it's very funny in lots of different ways. People see it sometimes in an incredibly positive way that they think that, you know, again, sharks are almost godlike and have these abilities. I also -- you know, little kids constantly say to me, who's going to win in a fight between a killer whale and a shark. I mean, there's lots of different ways people see this, but I find it interesting that we're so fixated on this creature who, you know, many of us don't see often, but yet it really just looms large and it's something that we care about.

REHMSo at one point, you got into the water and there was kind of a face-to-face confrontation with a shark. Tell us about that.

EILPERINThat was one of my funniest encounters with sharks. This was...

REHMFunny she says. Funny.

EILPERINBecause I survived.

REHMYeah, right.

EILPERINIn the end, I survived to tell the tale. So I was swimming off the Yucatan in a place called Isla Holbox, which is a beautiful, beautiful sleepy island where, actually, there they've made whale shark tourism into a real economic driver of the region and so whale sharks are the biggest fish in the sea, they can be the size of a school bus and even larger than that. And -- but what's great about them is that they're -- they feed on the smallest fish in the sea. They're filter feeders and so there's no question, they're not gonna chomp you with their jaws.

EILPERINBut at one point, when I was -- I kept trying to swim with the whale sharks and they move a mile an hour and I don't swim a mile an hour, so I kept being left behind, so I finally figured out that I should just jump in on the front end in front of a whale shark that was heading my way. And then it occurred to me as the whale shark, this massive, massive fish was approaching me, that I could get run over by it, the same way you could be run over by a school bus, so I actually had to swim out of the way and I managed to avoid it, but that, in some ways, was my most -- my closest call with a shark.

REHMAnd was this a tame shark, if you will, as far as man or woman is concerned?

EILPERINAbsolutely. It's -- you can have a little kid snorkeling with this whale shark and that kid will be fine as long as he or she manages to stay out of the way.

REHMYou know, Juliet, this must also bring up for you the concern about aquaria...

EILPERINYeah.

REHM...around the country and enclosing these glorious creatures of the ocean...

EILPERINRight.

REHM...within glass.

EILPERINIt's an interesting question. I mean, I have to say that I've spent a lot of time with some fantastic folks from aquariums. We obviously have the National Aquarium, both the downtown division as well as Baltimore, the Monterey Bay Aquarium, have scientists who I've dealt with a lot. The Monterey Bay Aquarium, for example, is the only place where they've been able to contain a great white in captivity on different occasions and it's a very interesting question.

EILPERINThere was some controversy about it, but what they do do is they take a juvenile white shark, they have the shark in the tank for a limited period of time and then they tag it and release it and track how it's doing. And by all indications, the sharks that often had been caught inadvertently by fishers do fine once they're released.

REHMJuliet Eilperin, the book is titled "Demon Fish." Short break and then your calls. Stay with us.

REHM"Demon Fish" is the title of Juliet Eilperin's new book, her travels through the hidden world of sharks. And what a fascinating world that is. Let's open the phones first to Stan in Durham, N.C. Good morning to you.

STANGood morning, Diane. I was just a little bit surprised that nobody brought up the fact that the sharks are major scavengers in the ocean. And without them, the oceans become polluted. I mean, we have something twice the size of the state of Texas was plastic in the upper Pacific, but without the sharks, the whole thing goes down.

EILPERINStan, you're absolutely right. And, in fact, I made a brief illusion to it, but there's no question that they go out after the ailing fish, they have incredible senses and they can tell if a fish is struggling. One scientist, Rachel Graham, from the Wildlife Conservation Society who works in Belize makes her pitch and says, how would you feel if the garbage collector didn't come for one week, didn't come for a month, didn't come for a year? If you wipe you sharks, what you're losing is that ability to clean up the oceans.

REHMBoy, that is a strong point to make, isn't it?

EILPERINYou're right. It's really -- it's one of those things you don't think about, but again, this had operated for millennia without us changing it and then once we really started significantly changing it, that's when we noticed what they did.

REHMLet's go to Jacksonville, Fla. Claudine, you're on the air.

CLAUDINEHi, there. Thanks, Diane. I love your show.

REHMThank you.

CLAUDINENow, I have a question. I'm in public health and we have advisories for our coast, Jacksonville Beach particularly, but we know that the larger predatory fish tend to concentrate mercury from the environment and we don't recommend that anybody eat shark. That's one of the fish to avoid. What role do you see in the future worldwide for the demand for shark meat when we know that it is contaminated?

EILPERINThat's an excellent point and it's certainly one of the points that, for example, advocates use in Asia when they talk about this. There's no question that they're very high in mercury, they've tested it, whether you're talking about Thailand or China and it really does pose a level of a health threat that, you know, it's something that people might take into account, but you have to counteract the idea that in Chinese society, when I talk to people about it, they say, it's good for your health, it gives you a long life and it's really something you should be eating.

REHMHere's an email, let's see, from Jen in D.C., who says, "Fear is one of the two fundamental drivers of human behavior. Steven Spielberg mastered his audiences in that respect. It would be so wonderful if he, having made so much money on 'Jaws,' would vocal a visibly and financially take on the cause of our Persia sharks." Did Peter Benchley do that?

EILPERINHe absolutely did. I didn't have a chance to get in touch with Steven Spielberg. I couldn't reach him for the book, but with Peter Benchley, who unfortunately died a few years ago, I do know his wife, Wendy, who is an ocean conservationist herself.

EILPERINAnd Peter, before his death, did a tremendous amount. He teamed up with Greg Stone, a scientist, who now works with Conservation International, as well as the New England Aquarium. He did educational programs on this. He toured not only the United States, but Asia to talk about this issue, so there's no question that he came to appreciate the role sharks did. And, in fact, he was one of the most effective messengers when it came to preserving sharks.

REHMLet's go to San Benito, Texas. Good morning, Phil.

PHILGood morning. Hi. The author said she's been asked by little children all the time who would win in a fight between a killer whale and a shark, but she didn't say who would win.

REHMShe was saving it, I think, Phil.

EILPERINExactly. You know, it's a good question. If I had to bet, I probably would bet on killer whale, but, you know, I think it might depend on the outcome of an individual contest. There's no question it would -- you know, it would be an entertaining thing to watch, although bloody in the end.

REHMAll right. To Alexandria, Va. Hi there, Sean.

SEANGood morning. I was rather surprised to hear that 73 million sharks a year are the estimated take. And, well, as a conservationist, I find that unsettling, but as a surfer and ocean swimmer, I also wonder if, say, over the last five years, that would be a couple 100 million sharks that would still be in the ocean and I was wondering what the effects on fisheries at large might be, but also, would the attacks against humans also be expected to increase if we cut back on the number of shark takes?

EILPERINWell, that's a good point as well. I mean, really, the biggest determinant on what level of attacks there are on humans are how many of us go to the beach. So one thing that you've seen is there are really close correlations. There's something called the International Shark Attack File, which is the best accounting of how many attacks there are worldwide as well as in the United States on humans when it comes to sharks. And really, as human populations grow and as people have more money to take vacations and spend time in the water, that often is what determines whether or not you have sharks.

EILPERINBut your caller makes a good point, which is that also, when you not only protect sharks, but you also, for example, protect seals, their prey, what you've seen is more recent -- there have been additional sightings of great whites off, for example, the Cape Cod and the Massachusetts coast in recent years, so, you know, again, you shouldn't have any illusions. If you're gonna -- if you do something to protect sharks, there are going to be more of them around, but, you know, it still is a very small fraction.

EILPERINI should say for surfers, one thing to keep in mind is when people go surfing around dawn and dusk, that's one moment when sharks could be feeding, so one way to play it safe is to not be in the water where sharks might be at those times where visibility is not that great and you could have a greater chance of running into a shark.

REHMAre sharks normally interested in human beings?

EILPERINNo, they're not. And basically, almost every time a shark takes a bite into a human, it's by accident. There's one researcher in Australia, Christopher Neff, who says we're in the way, but not on the menu. And I think that's a good way to put it, that there's definitely moments where there is an interaction there and sometimes it's -- you know, it takes a serious toll on a person, including it can kill them, but they're not intentionally going after humans.

REHMWhat about that story I've heard so many times that if you have your wits about you, you can punch a shark in the nose and head him off?

EILPERINThere is some evidence to show that that works. Again, luckily, I've never had to practice the nose punch to the shark, but that's what I would do (laugh) if I was faced with that.

REHMJuliet, how long do they normally live?

EILPERINYou know, there -- we don't have -- it both varies by species, but also, we don't have very good estimates on that. You know, there are some that we think that can live certainly more than 70 years, particularly really deep water sharks. Some live shorter than that, but, you know, again, that's one of the things that scientists are still trying to figure out.

REHMAll right. To Silver Spring, Md. Good morning, Bruce.

BRUCEHello.

REHMHi.

BRUCEHello. I'm a scuba diver and I've doven many times with sharks in North Carolina and we've always talked about the possibility of shark attack, but no one I've ever known has had a problem as a diver. And the law about that is that when you're at the surface, you're casting a shadow into the water and really, any fish below you or anything below you really can't see what you are. You look just like a shadow and a shadow could be interpreted as a seal. And so you're basically a good target.

EILPERINBruce is right. The fact is that there are far fewer incidents of divers being struck by sharks as by surfers because of that, because the board casts a long shadow and can in some ways, seem like it looks like a seal or a sea lion from above.

REHMInteresting email from Don in Moscow, Idaho, who says he was told by a health expert to take shark cartilage for arthritis pain. How do they get this cartilage from sharks?

EILPERINWell, they get them by killing them (laugh) is the short answer. And I have heard that and the question really is I don't think that there's robust scientific data that indicates that that's the best thing you can take for arthritis and I'm sure there are things you can take, but there's no question that there is a booming medicinal trade in sharks.

REHMAll right. And to Jacksonville, Fla. Hi there, Walter.

WALTERGood morning. I'm a kayak fisherman and just recently found that sharks are more than just an irritant while I'm tarpon fishing, that they were delicious, but your earlier comment kinda took the wind out of that. Was wondering if you could talk about the blacktip population and how it's going.

EILPERINThe blacktip population, well, I don't have exact numbers on it, it's not one of the populations people talk the most often about being endangered or threatened with extinction, so I'd certainly say that, you know, one -- I could tell one reason for that is their fins aren't as large, so they're not targeted by...

REHMInteresting.

EILPERIN...by shark finners the way others are, so that's one of the best indicators of whether a species is doing okay or not.

REHMHere's an email from Raleigh, N.C. Tommy says, "Fishing and finning are certainly problematic, but isn't the shark's worst enemy global warming?"

EILPERINGlobal warming, which brings with it ocean acidification, is the real issue. I know Ted Danson talked about this last week, that the idea is that with more carbon dioxide going in the air, you know, what you're having is there's -- the seas are becoming more acidic and that makes it harder for particularly marine species at the bottom of the food chain to form their calcium shells, so that's a problem for them also.

EILPERINThe prey are shifting locations and so the sharks are going to have to shift locations as well if they're gonna feed on the same species that they've been targeting, but I wouldn't say that that's their immediate most serious threat. There's pretty strong evidence that fishing is their deepest worry.

REHMAnd here's another, "Please touch on the subject of shark feeding dives and how it conditions sharks to relate to people as a food source."

EILPERINWell, there are scientists that are looking at this, the idea that often your best bet at seeing a shark is when a charter boat captain chums the waters, takes chopped up fish and puts it in and attracts sharks that way. So really, there's mixed evidence on this. I would say that we don't have enough data right now to determine whether this is conditioning sharks. It certainly does condition, for example, rays in the Grand Cayman islands. There's pretty compelling evidence that rays went from being nocturnal to diurnal because of being fed by tourists, so it's definitely something that we need to monitor.

EILPERINBut it's a very tough call because shark ecotourism is one of the greatest ways to combat shark fishing because you're making an argument that they're better off being preserved alive than dead and so it's a tough tradeoff. There's also concern when people watch sharks attacking their prey, for example, off the coast of South Africa, that all the noise is disturbing them and could ultimately affect that feed relationship.

REHMHere's an email -- sorry, a caller in Utica, N.Y. Good morning, Donna.

DONNAHi. I was wondering about the music and the sharks. Do sharks have hearing or are they listening to vibrations? And also, you were talking about midlevel predators. Could you name what some of those predators are?

EILPERINSure thing. So in terms of they do have good hearing, so there's that, although she's absolutely right that they are incredibly good at picking up vibrations and that's one of the main ways...

REHMBut they do hear?

EILPERINYes. They do actually hear. But what I would say on the...

REHMDo they have ears, ear canals? How do they hear?

EILPERINYou know, I know they sense it, but I'm not a huge expert on this, but I know -- you know, what's interesting is, now that you mention it, I know there's actually someone I know who did a great story that we have studied shark hearing. There's someone who studied it to try to figure out because they can regenerate their hearing capacity in a way that humans can't, so there actually is a scientist who's working on this and I'm actually trying to get in touch with that person...

REHMInteresting. Yeah.

EILPERIN...but I have not done it yet, so I know that they can do that, but -- and in response to her second question, cownose rays, which people might be familiar with is a classic example of a midlevel predator. You know, the rays that, again, are related to sharks through their lineage and but when sharks are wiped out, their populations can explode and it's a problem whether you're talking about the Chesapeake Bay or further down off the Atlantic or, you know, in other areas as well.

REHMAnd you're listening to "The Diane Rehm Show." Let's go to Salt Lake City, Utah. Good morning, Gary.

GARYHi, Diane.

REHMHi.

GARYI love your show. It's the third time I've called in. I saw the movie "Soul Surfer," the story of Bethany Hamilton, the wonderful surfer, wonderful young surfer who very tragically had her arm teared off. And one of the points in the film, there's a scene in the film where the shark is caught and killed and actually turned into kind of a trophy and I don't whether that was actually an accurate rendering of what happened in real life or not.

GARYBut I'm just wondering, one of the points that has been made -- and I've been drifting in and out of the show, so I'm not sure if I've -- this was already made or not, but, you know, I wonder what kind of a factor climate change has been in actually bringing these sharks closer to human habitats and the fact that there's such an intersection between, you know, humans and...

REHMSure.

EILPERINYeah, so while we have talked about it, climate change does affect their swimming patterns and, in fact, it's why recently there were a bunch of sharks that were seen off of the Florida coast and that alarmed some people, but really, it probably had to do with shifts in climate.

EILPERINYou know, there are two other points I would make. One is that surfers are often some of the most enthusiastic activist on sharks behalf. They've been working with groups like the Pew Environmental Group. There's even, again, shark attack survivors who lobby on behalf of shark protections. I've met several of them and it's incredible when you think of someone like Bethany Hamilton or others who really, despite having these horrific encounters with sharks, still are willing to protect them and see why they need to stay around.

REHMNow, Juliet, though we don't have time to take her call, Susanne in Winter Haven, Fla. says she lives near Orlando where restaurants serve shark fin soup. Is this allowed?

EILPERINAbsolutely. It's allowed not only in Orlando...

REHMStill allowed.

EILPERIN...but you can -- there are many Chinese restaurants you can go into up and down both the East coast, West coast and in-between that still serve it, so there again, it's only in these -- right now in these states in the Pacific Northwest and, you know, on the West coast that are speaking to ban it.

EILPERINYou won't be able to get shark fin soup fairly soon in some of those places. And again, it may happen elsewhere in the country, but right now, there are no prohibitions, you know, again, with the exception of Washington state that signed its law, you know, into effect. There's no other place where it's not allowed.

REHMWell, I hope your book pushes this issue and I'm sure it will awaken in many their interest, their understanding, appreciation of sharks. Thank you for writing the book.

EILPERINThanks so much, Diane.

REHMJuliet Eilperin, the book is titled "Demon Fish." Thanks for listening, all. I'm Diane Rehm.

ANNOUNCER"The Diane Rehm Show" is produced by Sandra Pinkard, Nancy Robertson, Susan Nabors, Denise Couture, Monique Nazareth and Sarah Ashworth. The engineer is Tobey Schreiner. Katie June-Friesen answers the phones. Visit drshow.org for audio archives, transcripts, podcasts and CD sales. Call 202-885-1200 for more information. Our email address is drshow@wamu.org and we're on Facebook and Twitter. This program comes to you from American University in Washington. This is NPR.