MS. DIANE REHMThanks for joining us. I'm Diane Rehm. A recent survey of California beaches found 140,000 bits of plastic trash for every 100 yards of beach. For this month's Environmental Outlook, marine scientist and conservationist Callum Roberts, he traces the history of the world's oceans and the dramatic impact human beings are having on the seas.

MS. DIANE REHMIn his new book "The Ocean of Life," Roberts proposes a new deal for oceans that aims to halt the growing crisis by establishing marine reserves and fishing less to catch more. Callum Roberts joins me in the studio. We'll welcome your questions, comments. Join us by phone at 800-433-8850. Send your email to drshow@wamu.org. Join us on Facebook or Twitter. Good morning to you, sir, it's good to have you here.

MR. CALLUM ROBERTSGood morning.

REHMI would like to start with a bit of history. You begin with the origins of the oceans. How were they formed?

ROBERTSWell, the oceans came from water which essentially was soaked up by the planet from outer space in the very early history of the formation of earth. So about 4.57 billion years ago, the earth began to coalesce from pieces of debris which were circling around an infant sun and the oceans then coalesced on to the planet from asteroid impacts.

ROBERTSThey also -- there was water in the dust there and eventually as the earth began to cool, so the oceans condensed from the vapor and the gas that was surrounding the planet and they began to form on earth. And so very early in the history of the earth, something like 4.4 billion years ago, there's evidence from the rocks, the earliest rocks on the planet, that there was liquid water around.

REHMBut then you begin to explore how oxygen got into that water.

ROBERTSThat's right. Well, we had to really wait until the origin of life for the world to become oxygenated and that didn't happen for some time. The very first life forms which flickered into life perhaps 4.1 to 3.8 billion years ago, they didn't produce oxygen. They produced methane, another kind of gas and they used hydrogen sulphide as their energy source rather than sunlight. But eventually the transition was made, the great innovation of creating energy from the sun, photosynthesis, and then an oxygen-producing form of photosynthesis evolved.

ROBERTSAnd so we have what's called the great oxidation event which was happening around 2.4 billion years ago as the oxygen levels then began to build up on the planet.

REHMSo what you're saying is we could not have been swimming in that water before the oxygen got into it?

ROBERTSNo. We would have been snuffed out in a moment in this early world. And it was really a world that was the kingdom of the microbes, little microscopic creatures that were living in all sorts of bizarre lifestyles. But at the time, this huge span of time, for billions of years, they were forming the cellular chemistry upon which all of our life is based.

REHMBut you call us, that is, we humans, creatures of the sea. How do you arrive at that?

ROBERTSWell, there is an argument that we owe our very big brains and our cleverness to a diet that's rich in seafood. And one of the reasons is that the nervous system was formed in the oceans and so the evolution of those nervous systems happened in the sea long before we ever came along as multicellular life was emerging.

ROBERTSAnd the building blocks of nervous systems are these fatty acids that we have from marine life, the omega-3 fatty acids that we see as being healthy and good for our hearts these days. And so those are in short supply for animals that live on land, generally speaking, and so we couldn't afford to create a big brain. But it's interesting that some of the earliest evidence of modern humans comes from South Africa, right on the coast and they were eating shellfish. They went down to the shore to gather lots of shellfish and the caves, the dirt in the bottom of the caves there, which gives us evidence of their lives is rich in seafood and so that we can see that people were eating seafood a very long time ago.

REHMCallum Roberts, he is a marine scientist, a conservationist, professor at the University of York in England and author of an earlier book "The Unnatural History of the Sea." The book we're talking about today is titled "The Ocean of Life: The Fate of Man and the Sea." I hope you will join us, 800-433-8850. This book is very worrisome because what you're doing is tracing the life of the ocean, what's in it and what's happening to it. You talk about the history of fishing from its earliest time to now. What's happening?

ROBERTSWell, fishing, as I've just mentioned, was one of the earliest ways in which people affected the sea. It took a very long time, though, for commercial fisheries to develop and we see the earliest evidence from them in the Black Sea and the Mediterranean. In fact, a kind of canned tuna was being shipped around the Black Sea even five millennia ago. You know, 5,000 years ago just think that people were packing amphorae with fish and then shipping them hundreds or even thousands of miles. That's quite extraordinary.

ROBERTSBut it's only in the last 100 years or so that we have seen the industrialization of fishing and that happened in the late 19th century when people added engines to their boats and everyone wanted one. So by the beginning of the 20th century really, the ports were full of engine-powered vessels and that changed fishing forever because it meant that we could drag much bigger fishing gears. We could get out further and faster. We could bring back fresh fish from further afield. We could go deeper down in the oceans.

ROBERTSAnd then we have Clarence Birdseye coming along and he invented flash freezing and so that enabled people then to go even further offshore and preserve fish from much further afield. And so the impact of fishing has spread across the oceans since then.

REHMAnd the assumption has always been that there would be more fish, that no matter how much you took from the sea, there would be more to follow. What's happened?

ROBERTSWell, fish are the perfect renewable resource so if you take less than is being produced every year or thereabouts, then you will have fish forever. But if you take a little bit more than is being produced every year, then your capital, your amount of fish will dwindle over time.

REHMAnd that's what we're doing?

ROBERTSThat is what we're doing. And we manage to sustain this kind of exploitation of the sea, serial over-fishing as it is called, because we've been switching from one species to another. So the things that were familiar to us in the 19th century or the early 20th century, many of those species have been depleted a long way now and so we no longer catch them and we've switched to other things.

ROBERTSAnd typically, you know, we're eating a lot more squid today than we used to do. People would use that as bait 50 years ago. Fifty years before that, they would use lobster as bait. So we're switching to other things that are more abundant as we deplete fish that we've formerly prized.

REHMSo what you're saying is that all of this improved technology did not really make the life of a person doing the fishing easier. In fact, it's made it more difficult.

ROBERTSThat's right. The paradox of improving technology is that it's always chasing a dwindling prize. So we're innovating and improving the ability to catch fish because the amount of fish that are out there to be caught is in decline and so we have to. If you want to carry on fishing, if you want to make a living, then you need to find better and better ways of catching fish. But ultimately there is an end to that and that comes when there aren't any other fish that you can switch to.

REHMIt's interesting that you say fully two-thirds of species fished since the 1950s have collapsed and the rate is now accelerating. What kind of fish are you talking about?

ROBERTSWell, there are animals like the Blue Fin Tuna, the Atlantic Blue Fin Tuna, which is a species that has been prized since ancient times. And that was described in poetry 2,000 years ago and the methods of fishing it were exquisitely sophisticated at that time in the Mediterranean. It was caught in the North Atlantic in abundance off the east coast of the United States from Long Island all the way up to Nova Scotia and Newfoundland.

ROBERTSIn the eastern North Atlantic, we were catching them as far north as Norway. But over the last 50 years, those stocks have dwindled and dwindled so there's now none left in the North Sea. You never really see them south of Nova Scotia now in the east coast. We're not finding nearly as many Blue Fin Tuna because the population has just collapsed down to such a small level.

REHMAnd then you have the diminishing size of some breeds of fish.

ROBERTSThat's right. And what happens is that if you intensively exploit an animal, then you're going to be taking out the big fish and progressively the size of the fish dwindles. And in part, that's an evolutionary response by the fish to the increasing exploitation level because they've got to breed earlier at smaller sizes if they're going to survive.

REHMMarine scientist Callum Roberts, his new book is titled "The Ocean of Life." When we come back, we'll talk for further and take your calls.

REHMAnd welcome back. Callum Roberts is a marine scientist, a conservationist professor at the University of York in England. His new book is titled "The Ocean of Life: The Fate of Man and the Sea." You talk about the cautionary tale of Firth and Clyde. Explain that one for us.

ROBERTSWell, off the west coast of Scotland, there's an inlet of the sea which extends for about 100 miles inland. And it's a place which was, 200 years ago, extraordinarily bountiful. It was a very intensive title system which flushed in and out nutrients that fueled plankton growth. And enormous sholes of herring would come in to feed on the plankton and of course, they drew in predators of whales and dolphins and seabirds and other fish. And it was probably one of the most prolific places in the seas around northwestern Europe.

ROBERTSAnd yet what has happened over time, there is that we've seen the progressive elimination of one fish species after another as the Clyde has gone into decline. We've been fishing too intensively. The herring collapsed in the 1960s. That meant that people switched to fishing using bottom trolls that were dragging their nets along the seabed and trying to catch bottom-living fish, like cod and haddock and halibut.

ROBERTSAnd then the stocks of those fish began to decline and we switched even smaller and we started to fish for prawns. And if you know the size of a prawn, you know you have to use a small mesh on the net to catch them. And that meant that all the young of the fish started to get collected up as well. And so we've seen the Clyde transformed within a period of only 50 years or so from abundance to scarcity. And there's now only two animals that are really sustaining fisheries there, and that is the prawns and the scallops, a kind of a shellfish.

REHMNow, the question becomes whether, in fact, natural evolution is progressing along with manmade efforts to deplete those waters. In other words, is nature in part at fault or is it all man?

ROBERTSWell, it isn't entirely man, but I think in the case of a place like the Firth of Clyde, it's 90 percent people overexploiting and 10 percent other kinds of changes. But more broadly in the oceans, the oceans are changing at a remarkably rapid rate under a whole variety of influences that ultimately come down to us. And so there is the global warming side of things with greenhouse gas emissions and, in particular, releases of carbon dioxide into the atmosphere. That is doing to the oceans much as it is doing on land. It's warming them up.

ROBERTSBut it's also causing the oceans to become more acid as the carbon dioxide dissolves into the sea. And that's making life very, very difficult for any animal that has a shell -- a chalky shell or a skeleton, like corals and certain kinds of plankton because they find it much harder to extract the building blocks of those shells from the seawater under acidified conditions.

ROBERTSAnd then, of course, we've got pollution which is building up in the oceans. And in particular, the biggest kind of pollutants, the most worrying ones are the runoff of nutrients -- the fertilizing nutrients, particularly from agricultural runoff, where we're putting more and more in the way of fertilizing chemicals on fields to sustain their productivity. And a lot of that is ending up in coastal oceans.

REHMSo if you can look back 4.5 billion years, considering what you've done with this book, considering the kind of research you do, what do you predict 100 years from now as far as our oceans are concerned?

ROBERTSWell, that depends on how we treat them. And if we just carry on as we're going, then we will see the oceans progressively losing more and more of their larger life. We're depleting the populations of the big fish. We're seeing the giants of the sea dwindling in numbers. And they're being replaced by smaller and smaller animals. And so we're getting tiny fish and prawns out of the sea right now.

ROBERTSWe're also seeing the seas increasingly changing for the worse as a result of the pollution, for example. So there are dead zones that form seasonally in many parts of the world. More than 400 places around the planet now are depleted of oxygen every year or even permanently because of over-fertilization by nutrients.

REHMHow do you know? What do you see? What does it look like that these dead zones exist?

ROBERTSWell, when you go into a dead zone, there's really very little in the way of living bigger animals present. They can't tolerate the absence of oxygen. And so it looks like a cemetery sometimes. If the oxygen has just been depleted, you'll often find the bodies of animals scattered across the seabed, crabs that haven't managed to escape from the low oxygen pall that is spreading across the seabed.

REHMAnd what about the debris that we're now seeing coming from parts of Japan, other parts of the world to the shores of the United States?

ROBERTSWell, that's right. The tsunami debris has been making its way across the Pacific, hitching a ride on the great currents that circulate around the whole of the ocean basin. And the thing about those currents is that there are these still areas in the middle of them. They're called jars and in the center of those jars, it tends to accumulate all kinds of things.

ROBERTSAnd we have produced, in the last 60 years, an enormous quantity of plastics. And we've been really reckless in how we dispose of them and much of that plastic is finding its way into the oceans. And it's gradually crumbling and breaking down into smaller and smaller pieces. And we're finding those areas -- those big still areas in the middle of these circulating water masses are filling up with plastics and all kinds of other trash.

REHMHave I heard correctly that there is one area of the ocean about the size of Texas that is nothing but an island of plastic?

ROBERTSIt's not quite an island. If you were to sail through it, you would see lots of floating trash there. And in places, there would be rafts of it and huge old fishing nets. But it's not exactly a solid island as yet, but, you know, it is beginning to get to the state where you can see large chunks of rubbish that are coalescing in those areas, yes.

REHMHere is an email from Carol who says, "Diane, in your opening remarks, you said human beings are causing the degradation of the seas. Human beings have been on the planet for a millennia without causing harm. The real culprit is industrial production, which not all humans engage in. Until we can be clear about the fundamental causes of the destruction of our seas and planet, we will not be able to address this important issue effectively. Blaming human beings leads to the assertion that the planet would be better off without humans when, in fact, the earth is fine with humans. But industrial production is killing us all in many different ways." Would you agree with that?

ROBERTSI think the big drivers of the changes that we're seeing on the planet all come down to us. Essentially, we have increased extraordinarily in our population size in the last 50 or 100 years or so. And there's been no precedent for that in human history with now 7 billion people on the planet. And that's an increase from about 3 billion in the 1950s. That's an extraordinary increase.

ROBERTSBut allied to that is our increasing affluence and that's where the industrial production comes in. And, you know, I would say that most normal people aspire to a comfortable lifestyle and that requires a lot of industrial production to support it. And that's really fueling our energy use and causing the problems of greenhouse gas emissions and so forth.

ROBERTSSo what I argue in the book is that we have a crisis coming up ahead and that is developing as a result of the climbing human population, the increasing number of middle classes who are consuming more and more. And it won't peak-out until the middle towards the end of the 21st century, which means that conditions are going to get worse for the oceans and for life there before they get better.

REHMInteresting, though, you say one ocean species seem to benefit from overfishing and that's jellyfish.

ROBERTSThat's right. Jellyfish are animals that are remarkably adaptable in this kind of changing world. They don't have a chalky skeleton so they don't mind ocean acidification. They enjoy a nutrient-rich broth. They can grow extraordinarily rapidly under those conditions. They don't mind a bit of warming. And they also thrive in the absence of predators that used to eat them. And so when we're overfishing the predators that eat the jellyfish, we are creating the conditions for jellyfish explosions.

ROBERTSSo I think the whole combination of conditions that we've got in the oceans could not have been better designed by some jellyfish megalomaniac intent on world domination.

REHMSo what progress do you think the U.S. has made? Has it taken a role of leadership in trying to protect the oceans or are other countries around the world doing better than we are?

ROBERTSWell, the United States is doing well in terms of managing its domestic fisheries. After decades of intensive overexploitation, finally there was -- in the reauthorization of the Magnuson Act a few years ago, it was made illegal to overfish. And so essentially now the Fisheries Management Councils, which are scattered around the United States, have to implement measures that will end overfishing. And that is leading to some benefits already. And we're seeing the recovery of some fish stocks, which were formerly knocked down to very low levels.

ROBERTSIn that sense, the U.S. is leading, I think, internationally. Europe, for example, has among the worst fisheries management in the world. We've seen our stocks depleted to extremely low levels and all the politicians seem to be able to do is to argue among themselves over a dwindling share of the pie, which is getting smaller and smaller every year.

REHMSo it comes down to politicians, lobbyists, the fisheries industries themselves arguing we want more and more and more.

ROBERTSThat typically is what has happened. And over the years, politicians have given into that lobbying and have sidelined the environmental effects of the intensification of fishing. And I think we're now beginning to reap the rewards of that because we're seeing the symptoms of problems emerging all over the place. So we get toxic red plankton tides in Florida, for example. We see fish kills increasingly. There are flesh-eating microbes, which cause problems in the Chesapeake Bay. There are dead zones that form off the coast of Oregon. We're seeing all these emerging problems that are symptoms of the way in which we are abusing the oceans.

REHMCallum Roberts and he is the author of a new book. It's titled "The Ocean of Life: The Fate of Man and the Sea." And you're listening to "The Diane Rehm Show." We'll open the phones now. First to Dallas, Texas. Good morning, Jerry.

JERRYGood morning. Can you hear me?

REHMI certainly can, sir. Go right ahead.

JERRYI was concerned and curious about the Sea of Cortez, which runs along the inside of the Baja Peninsula, Baja, California. I was there on vacation a few years ago and there were fishing boats coming in by the (sounds like) chins that had at least seven sailfish on them for people who were fishing. And I've never seen so much fish coming in and being cleaned. And I don't know what they did with it, but it's a very prolific sea and I wondered how that is being affected.

ROBERTSWell, the Sea of Cortez is, as you say, an extraordinarily prolific sea. It was one of those places that John Steinbeck visited and wrote very eloquently about during the 1940s. And it's an amazing place. It has this incredible production and it's naturally very abundant. But it has been affected quite badly by the intensification of fishing but also by other changes.

ROBERTSSo if you go to the Northern Sea of Cortez, the Colorado River used to flow into there and enrich the waters of the northern Gulf so that there were extraordinarily prolific fish stocks. Something -- an enormous fish that's about two yards long, called the totoaba, used to go and breed in the waters of the Colorado River. But now there is no Colorado entering the Sea of Cortez. It's dried up as a result of us diverting all of the water for crop irrigation and for use for drinking water. And so the environment there is changing dramatically as a result. It is still one of the most prolific places in the world, but it is declining, too.

REHMAll right. Caller here in Washington, D.C. Good morning, Lydia.

LYDIAHi, Diane. Thanks for doing this show.

REHMSure.

LYDIAI had a question about a different ocean, the Arctic Ocean. And I'm curious about what you both think about President Obama's plan to let Shell start drilling for oil there later this summer. From what I have read from the Sierra Club and Alaska Wilderness League, Shell doesn't really have a cleanup plan that they've shared with anyone. And I gather the closest coastguard station is about 1,000 miles away and the conditions don't seem great for a speedy rescue.

LYDIAAnd we saw in the Gulf when the coastguard was right there how long it took for that cleanup, so anyway, thoughts on that. It just seems like a crazy decision for the Obama Administration to be making.

REHMThanks for your call.

ROBERTSI agree with you that drilling for oil in the Arctic is just asking for trouble. If you think it was hard to bring the deepwater horizon blowout under control at a mile down, it will be ten times as hard to deal with a cleanup in Arctic waters with the seasonal ice there. And I think it's a crazy decision to go up there and start exploiting when there are much safer sources of oil still to be exploited.

REHMWhat about the fish and wildlife in the Arctic?

ROBERTSWell, it is a place that is teeming with life. And some remarkable productivity goes on there. I mean, there's a good reason why the gray whales migrate all the way from Mexico right up into the Bering Sea and the Arctic waters and the Chukchi Strait. It's because there is such an amazing amount of life going on up there. And, in fact, the United States fisheries are very prolific in that region, too. And so if we start seeing oil contamination of that region, then it could have a major impact on seafood supplies as well.

REHMCallum Roberts. He is a marine scientist, professor at the University of York in England. His latest book is titled "The Ocean of Life: The Fate of Man and the Sea." We'll take a short break here. When we come back, more of your email, your phone calls, your Tweets. I look forward to hearing from you.

REHMAnd welcome back. Callum Roberts is with me. We're talking about his latest book titled, "The Ocean of Life." And Elizabeth tweets, "My kids are in the back listening rapt. What's industrial fishing, Mom?" I think it's a wonderful explanation that you could offer, Callum.

ROBERTSIndustrial fishing is really an intensification of non-industrial fishing. For centuries we fished using nets and hook-and-line or spearing fish. And indeed a common way of catching fish 200 years ago was to just wade along the tide line in your bare feet and wait until you disturbed a fish and then you'd spear it. But industrial fishing is really the increasing intensity of exploitation that we get so that we're using large-scale fishing methods. We're blowing up these traditional methods into enormous (word?).

REHMHow large are these nets?

ROBERTSWell, some of the trolls that are pulled in mid waters could swallow a fleet of jumbo jets whole and they wouldn't touch the sides, so really very, very large. The trolls that are dragged across the sea bed, they can be 100 yards wide easily. And they tow for miles and miles every day. And sometimes they will go for six hauls a day with hardly any time between. So it's just this continuous process of extraction of fish from the oceans with very little concern about the impacts on the environment, on other wildlife.

REHMAnd of course, what they're bringing in with these nets are not just the fish they're after. They're bringing in everything else.

ROBERTSThat's right. What happens when you drag a net across the sea bed is it will sweep away all before it. So it's not just the fish that you want. It's also the fish that you don't want. And somebody has likened it to dragging a net behind a helicopter across a farm and you snag a few cows there, but you also catch the dog and the farmer and all sorts of other things that you don't want. And those are just discarded dead on the whole, from the boats. They're not even brought to shore. So it's a very wasteful way of catching fish.

REHMSo Elizabeth please tell your kids, good question. I'm glad they asked. Let's go back to the phones to Louisville, Ky. Sumshi (sp?) , you're on the air.

SUMSHIOh, good morning. It's been really interesting hearing all this stuff pertinent to our times now, but let's go back to when you first started; your guest started talking about the early stages of the oceans.

REHMSure.

ROBERTSI took some oceanography courses in college. I was amazed at the interconnectivity of the rest of the world and the ocean. It's like, you know, there's so much connection. But what really confuses me was we know a certain amount about its state now. You spoke of it being without oxygen at one time. And you're talking about billions of years ago. How in the world -- is there any way for you, in a concise and understandable way to us all out here, how in the world can you state and say with certainty -- what tipped you off that things weren't that way back then?

REHMAnd Sumshi, I need to apologize because that's a question I should have asked. It was in my brain and I wanted to move on. Go ahead, Callum.

ROBERTSWell, we can tell a lot about the conditions of the early oceans from the rocks that were laid down in those oceans. And so from the chemical composition of those rocks we can tell whether there was life around or not. And the signatures of life, the development of unnaturally complex carbon compounds, for example, we can see that in the early rocks from 3.8 billion years ago from Greenland. And so we know that life must have evolved by that time.

ROBERTSWe can also tell whether the rocks were being laid down in conditions where there was free oxygen around or not. And if there was free oxygen around, you would expect to see the rocks dominated by oxides, but if there isn't free oxygen around, then they tend to be dominated by sulfites. And so it's really from the chemistry that we can tell what was going on.

REHMAnd what did you see in South Africa that was different from then?

ROBERTSWell, in South Africa, this moving back to a couple of hundred thousand years ago when our own species really emerged on the planet, Homo sapiens. Then we have fully modern oceans and they're fully oxygenated. The sea is very much like it is today in fact, except that, you know, for a few fairly minor differences. Sea levels went up and down with ice ages and so the sea level dropped away from the caves at some times. It came back in at other times. But essentially, those are modern oceans much like the ones of today.

REHMNow, Sumshi, does that begin to answer your question?

SUMSHIIt answers the bulk of it. It's something I guess maybe I'll just have to go out and buy this book to understand more, right?

REHMI think so. Thanks for calling.

SUMSHIThank you very much. Bye.

REHMOkay. Let's go to Yasha (sp?) in Imnaha, Oregon. Good morning, you're on the air.

YASHAGood morning. Thank you. I'm addressing your first email where the woman talked about it's not human activity, it's industrialization. But what is industrialization, other than human activity?

REHMExactly.

YASHAHow do we address the disconnect? How do we get the education out there so that we know essentially we are killing ourselves and our children?

ROBERTSThat's a very good question. And I think we need to reinvent ourselves as the dominate animal on this planet. And that's essentially what we are. For most of human history, we have treated the world's resources as if there was no end to them. There was always enough for us to take. There was never much of a restriction. You know, yes, there were droughts and so on and that caused crisis in the past, but essentially the amount of resources on the planet was unlimited.

ROBERTSToday, we literally have filled up the planet. And we are, according to some estimates, using now something like one and a half planet's worth of resources if we were to be using them in a renewable way. And we have to transition from this approach of grabbing what we can to an approach of nurturing what we have and using them in a sustainable manner. And if we don't do that, then the future is very bleak indeed.

REHMYou talked about periods of warming in the Earth, in the oceans that occurred before 55 million years ago. You say there was a similar global warming with disastrous results. Coral reefs disappeared, vital plankton disappeared and the oceans changed dramatically. So what's different now? Why couldn't we simply expect that the oceans will renew themselves?

ROBERTSWell, I think the oceans will renew themselves. There is little doubt about that, but the question is whether we will be around to enjoy it.

REHMHow long.

ROBERTSIt's all about time scale. The ocean acidification I was talking about earlier, where we're dissolving carbon dioxide in the sea and it's increasing the acidity, that is a change that we're committed to now for thousands of years. It will take a very long time for any increases in acidity to reverse themselves. And so that means that the more we change it and the more difficult life becomes for the creatures that are secreting these chalky skeletons, those conditions are going to be maintained for a very, very long time.

ROBERTSSo it would be much more sensible for us to curtail the problem right now, nip it in the bud before it becomes terrible. And looking back in time to 55 million years ago, you can see these changes unfolded at that time. And as you say, coral reefs largely disappeared, the phytoplankton took a major hit. And the phytoplankton are important because they underpin all oceanic productivity. And so everything depends on them producing energy and material. And if they're gone, then the future is bleak indeed.

ROBERTSSo as a marine scientist, as a conservationist, if you could wave a wand now that would take perhaps not just the first step, but significant steps toward reversing the trend we're in, what would you tell our leaders to do?

ROBERTSWell, we have to treat the oceans in an entirely different way from the way we have been doing. And this is why I call a new deal for the oceans. And instead of knocking down the abundance of life in the sea to a tiny fraction of what it used to be, we need to rebuild populations of animal life in the oceans to much, much higher levels. And in doing so, we will give them a fighting chance of seeing through the really difficult times ahead.

REHMAnd how would you do that?

ROBERTSWell, there are a number of things that we need to do right away. And one is to increase the area of the oceans that we don't go in fishing in and create networks of marine reserves, areas that are protected. And I think that we need to be moving towards something like 30 percent of the oceans protected in this way with reserved dotted all over the sea. But in the rest, it's no use just carrying on business as usual there.

ROBERTSWhat we need to do is to fish less. And by fishing less, we can expect to see stocks rebuilding. We can expect to see habitats recovering from the damage that has been done, especially if we're using less destructive ways of catching them. But it doesn’t mean forgoing the seafood that we've all grown to love and enjoy because paradoxically if we fish less, we could be catching more. The reason for that is that if you can imagine that the fish in the sea are like money in a bank account, the more money you have, the more interest that you get every year from that capital sum on deposit.

ROBERTSAnd so if you have a small deposit, then you're gonna get a small amount of interest. If you have a big deposit, if you rebuild the stocks much bigger than you will get much more in the way of interest. So we could be getting more fish out of the sea rather than less.

REHMWould you put an end to industrial fishing?

ROBERTSI think we're always going to need to use industrial methods to extract fish from the sea, but it has to be in a way that is less intensive and less harmful. So we need to phase out the most damaging forms of fishing and replace them with lower intensity fishing. So yes that does mean scaling back some of the really big boats that are doing a lot of the damage and going back to some of the more traditional methods for taking fish from the sea, but those methods will be much more productive then they are today as a result of higher fish abundances.

REHMAnd what would you do about the runoffs from the land?

ROBERTSWell, we have to embark upon a big program of stress reduction for the sea. And that means controlling and curtailing the amount of pollution that is getting into the oceans and in particular we need to try and reduce the amount of nutrient runoff because that is behind the dead zone formation I was talking about. It's behind the emergence of harmful toxic algal blooms that are causing a lot of harm to wildlife.

REHMBut, you know, you're talking about these huge corporations. You're talking about huge money-making populations that depend on habits they've established to continue making the money and providing whether it's seafood, whether it's meat of one sort or another, they want to continue what they're doing on a large scale.

ROBERTSWell, this is true, but those corporations ultimately are on a high road to nowhere if they continue with the overexploitation of resources because there won't be very much to take. And you can just imagine those jellyfish burgers being produced by big companies. That's not really what people are after.

REHMCallum Roberts, his new book is titled, "The Ocean of Life." And you're listening to "The Diane Rehm Show." And to Paw Paw, Mich. Good morning, Rusty.

RUSTYHi, this is Rusty.

REHMHi.

RUSTYYou know, Diane, I'm a longtime listener, but a first-time caller. I'm happy to be on the show.

REHMI'm so glad to have you. Go right ahead.

RUSTYOkay. Well, I'm a whale fisherman myself. And I had a couple questions about the long-term sustainability of fishing a couple of different kinds of whales.

ROBERTSWell, the question with whales, whales have been exploited across the planet in huge scales since the 16th, 17th centuries. And increasingly through the 19th and 20th centuries, we saw whale populations knocked down to extraordinarily low levels. And now whaling is governed by a global moratorium. And so you're not allowed to go catching them most of the time, but there a few nations that continue like Japan and Norway and Iceland.

ROBERTSAnd they're catching mostly the smallest whales, the minke whales, but a few fin whales, as well. I think ultimately it's not about sustainability, it's about the morality of catching a huge animal like whales that concerns most people. And for much of the world, they've said no. It's too cruel and too problematic to kill such sentient beings. And so I think you have to make your choices there, but it's not about sustainability, given the numbers that we're taking right now.

REHMAll right. And finally to St. Louis, Mo. Good morning, Damon, you're on the air.

DAMONGood morning, Diane.

REHMHi.

DAMONThank you so much for this program. I really love anything that talks about the environment...

REHMGood.

DAMON...'cause just from my life experience, I'm 32, I don't really know anybody -- I don't have any friends that talk about the environment, you know, they're really concerned about it. And that's the problem. In a capitalist -- well, in a democracy, you've got to convince 51 percent of the population that this is what we gotta do. You don't have those kinds of numbers. And so I don't see us changing the situation. How do we move from what you're doing, which is educating us, educating the people that's listening, to actually taking control of the machinery of the civilization to do what we need to do to save this world?

ROBERTSThat's a very good question. And I think the communications, as I've heard it described as the tide that lifts all boats. And one of my reasons for writing this book really was to bring to much wider attention the problems that are gathering in the oceans right now. But I am optimistic about the future because I have seen a lot of change, yes, for the worse in the environment, but for the better in terms of the discussion of how to deal with environmental problems in the last 20 years or so.

ROBERTSSo when I started out in my career studying how marine protected areas worked and what they could do for fish stocks in the sea, there was hardly any of us talking about them or even knowing about them. And yet now we see them being discussed all the way up to the top at the United Nations. We see governments working to implement national networks of protected areas. They may not be moving fast enough or far enough as yet, but at least movement is underway. And so I am optimistic about the future, that this is a soluble problem and we can fix it.

REHMI'm glad you are optimistic and you've certainly educated us this morning. I thank you for being here.

ROBERTSThank you very much.

REHMCallum Roberts, a marine scientist, professor at the University of York in England. His new book is titled, "The Ocean of Life: The Fate of Man and the Sea." Thanks for listening. I'm Diane Rehm.