White Shark Sightings On The Rise On East Coast

Marine biologist Greg Skomal of the Massachusetts Division of Marine Fisheries says the increase in white shark sightings on the East Coast may be due to booming gray seal populations, which lure the sharks closer to shore, as well as bigger crowds on beaches — meaning more potential shark-spotters.

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From NPR, I'm Ira Flatow.

Over the last few years, there have been more and more confirmed shark sightings at beaches on the East Coast, and this summer is no exception. Just last week, lifeguards closed part of Rockaway Beach, that's here in Brooklyn, after surfers spotted a shark.

Further north, officials closed a remote beach in Cape Cod when a spotter of planes saw not one, not two but at least three great white sharks lurking near the shore a couple weeks ago. No one's been allowed in the water since then.

And then just yesterday, Cape Cod's Chatham Harbor was closed to swimming due to the sighting of a 14-foot great white shark. Scary, huh?

But before you call in Quint and his too-small shark boat in "Jaws," to put this in perspective, there hasn't been a fatal shark attack in New England since way back in 1936. So why are we spotting so many more great whites today?

Is their population growing, or are we just more paranoid and getting better at spotting them? Here to sort out some of the facts from fiction is my guest. Greg Skomal is a senior biologist at the Massachusetts Division of Marine Fisheries in New Bedford, Massachusetts. He joins us by phone. Welcome to SCIENCE FRIDAY, Dr. Skomal.

Dr. GREG SKOMAL (Senior Biologist Massachusetts Division of Marine Fisheries): Thank you, Ira. It's good to be here.

FLATOW: Good, thank you. Are there more sharks these days, or are we seeing more of them?

Dr. SKOMAL: I think it's a function, it's a number of variables we're dealing with here, and it's hard for us to really tell if there's more sharks or just simply more effort.

Certainly, a lot of the sightings along the East Coast of the United States have to do with more people utilizing the shoreline, utilizing the water for various recreational activities and otherwise.

But in think in some areas, specifically off the coast of Chatham, Massachusetts and Monomoy Island, we are indeed seeing more white sharks. And I think what we're seeing is a shift in distribution of the white shark in that particular area.

FLATOW: And what is attracting them to that area?

Dr. SKOMAL: Over the course of the last couple of decades, we've been seeing a steady increase in the number of gray seals and a growing gray seal, resident gray seal population in that area. I believe it's drawing these sharks closer to shore.

FLATOW: And why would we be seeing more gray seals now?

Dr. SKOMAL: Well, back in the early '70s, we passed the Marine Mammal Protection Act, and it's taken the last few decades for this population to actually recover to levels that pre-existed before we eradicated the species over the course of the last several decades. So we've got a growing population in response to protection by the U.S. and state governments.

FLATOW: So I guess what you're saying is that we're seeing a restoration of this coastal ecosystem to the way it used to be.

Dr. SKOMAL: Exactly, at least that's the way we perceive it at this time. You know, we could be going back to what existed several hundred years ago, with a robust seal population being preyed upon by a robust white shark population.

FLATOW: 1-800-989-8255. We're talking to Greg Skomal about the sightings of great white sharks along the East Coast. Maybe if you've seen one, you'd like to call in and talk about it. You can also Twitter us, send us a tweet @scifri, @-S-C-I-F-R-I. Or join the discussion on our website, on sciencefriday.com.

You, what do we you know, aside from watching "Jaws" and all the scary movies about sharks and Shark Week on cable channels everywhere, how much do we really know about white shark populations?

Dr. SKOMAL: Well, there are certain parts of the world where you can predictably find white sharks. And these areas, which include, you know, the Pacific Coast, California, parts of South Africa and South Australia - these are areas where scientists have had the luxury, if you will, of going out and studying these animals at great levels.

And we've been able to garner quite a bit about their biology in those areas, I think. One of the spots that we know very little about the white shark is the Atlantic Ocean. And perhaps, this change in ecosystem that we're going through up here in New England, may begin to provide us some access to these animals so we can start to tease away some aspects of their biology.

FLATOW: And you are involved in tagging sharks, are you not?

Dr. SKOMAL: Correct, correct. Yeah, last year we had a chance, for the first time, to put satellite-based technology tags on white sharks in this area, and we are already getting insights into their biology from those tags.

And already this year, we've placed four tags out, and we hope to be able to continue to do that over the course of the next month.

FLATOW: How do you get, you know, how do you know when it is time to reopen these beaches that have been closed?

Dr. SKOMAL: Well, you know, the local municipalities are in charge of those beaches, and all we can do at the Division of Marine Fisheries is provide information to those folks who are making these decisions.

You know, we'd like to provide real-time information on the presence of sharks as acquired through our research activities so they can make well-founded decisions on opening and closing beaches.

FLATOW: What are the odds of getting bitten by a shark?

Dr. SKOMAL: Well, you yourself indicated that the last fatal attack in Massachusetts was back in the 1930s. So that gives you a sense of what the probability is. That being said, I think it's important to realize when you place people in close proximity to the prey of sharks, namely gray seals, you could potentially increase the risk modestly.

So I think it's important for people to make wise decisions when getting in the water and choose areas that may be free of white shark prey.

FLATOW: Henry(ph) in Aurora, Illinois. Hi, welcome to SCIENCE FRIDAY.

HENRY (Caller): Hello there. Being landlocked, I just have an idea that possibly, there's less fish out there for the sharks to feed on because you could ask any fishermen why are they still in port. And the sharks will wander farther around, looking for food. That's my idea. Thank you.

FLATOW: You're welcome.

Dr. SKOMAL: Well, I'll tell you, that's an interesting point, and it points to fisheries management and population management and the importance of looking at bait species and to find relationships between sharks and their prey and whether or not we're, you know, overexploiting their prey and forcing sharks to other areas to exploit other resources.

That being said, I think it's well-defined, the behavior of the white shark, when it comes to feeding, these animals are clearly going through, clearly prefer larger prey, namely marine mammals and specifically seals and sea lions.

So I think what we have going on off the coast of New England is actually just a national predator-prey relationship and not anything exacerbated, perhaps, by humans.

FLATOW: Let's go to Roy(ph) in Sumter, South Carolina. Hi, Roy.

ROY (Caller): Hi, thank you so much for taking the call and specifically on this topic. It's always been an interest. I've been recreational fishing in the Atlantic for 30 years. And over the last three or four years, we've noticed a tremendous increase in the number of small sharks that we're catching.

It used to be something, we may catch one shark every two or three trips, and now we probably catch 10 sharks every trip. These we refer to them as bonnetheads. I dont know if that's an accurate terminology, about a three, three-and-a-half-foot long shark, always catch them on the bottom, never catch them trawling. And I'll take my answer off the air, but again, thank you so much for this topic.

FLATOW: All right. Could there be many big sharks because there are a lot more little sharks now?

Dr. SKOMAL: Well, you know, the bonnethead is indeed a species. It's considered to be a healthy population off the Southeastern U.S., according to the fisheries' statisticians. It's not a fish that's heavily exploited commercially, although it is sold in some numbers, and recreational fishermen like to catch it, as well.

You know, there are some folks who believe - some scientists who believe that with the removal of very, very large sharks that consume these smaller sharks, we're seeing more species, you know, more smaller sharks out there. That may be the case, although it hasn't been clearly demonstrated by scientists.

So it's an area where there is quite a bit of work, but we have no real conclusions yet.

FLATOW: Have sharks been over hunted?

Dr. SKOMAL: In certain parts of the world with certain populations, absolutely. We have enough information on, for example, the dusky shark to indicate that that population off the Eastern U.S. has been overexploited and reduced dramatically.

The same is true for the sandbar shark. For other populations of sharks, they continue to be robust, and I think the bonnethead falls into that.

FLATOW: All right, let me go to Mark(ph) in New Britain, Connecticut. Hi, Mark.

MARK (Caller): Hi, thanks for taking my call. As you said, I'm in Connecticut, and I've noticed changes in the water temperature of Long Island Sound. It's been creeping up, year over year, and I'm wondering if the climatic changes, increases in ocean temperature, are a possible source of increased activity.

FLATOW: Good question.

Dr. SKOMAL: Yes, an excellent question, one we anticipate a lot of research trying to answer over the course of the next decade. We know that with climate change and global warming, we're going to see changes in the structure of fish populations in terms of the diversity of species, with a shift north of tropical species.

And it has been demonstrated for some, already. I imagine with warming water temperatures in Long Island Sound, you're going to see a change in the fish diversity in that body of water, as well.

So, you know, it's an area that we're going into. We anticipate changes, and some of them have been documented. In terms of sharks, we haven't seen any kind of dramatic shift as of yet, but some of the species that typically occur south of Cape Cod and not north, have indeed been starting to creep around the Cape. So we're starting to see some indications that the fish populations, including sharks, are changing.

FLATOW: Steve(ph) in Cambridge, Mass. Hi, Steve.

STEVE (Caller): Hey, how are you doing? Thanks for taking the call. Great show. I think the shark thing is just a bunch of media hype, frankly. I mean, it just, you know, it makes people tune into the news shows, and I'm not sure there's any more or less. I just think the sightings are more - maybe because there's more fishermen out there.

But I was wondering if you might know why there's a lot more jellyfish in the bay this year.

(Soundbite of laughter)

Dr. SKOMAL: Well, you bring up a couple of excellent points, and a lot of the shark phenomenon, or shark frenzy, if you will, is driven by the media - and it's something we have to deal with all the time.

I can tell you that some of the shark sightings data absolutely indicate a shift that's going on over with white sharks, and some of it's just generated by a media frenzy. Somebody sees a fin, it may not be a shark fin, but it gets reported as such, and that just compounds upon itself.

I wish I could be of more help with you with jellyfish. I've been hearing a lot of folks complain about jellyfish in the bay over the last several weeks, but unfortunately, I study things a lot bigger.

FLATOW: All right, we'll have to take a look at that, with some jellyfish folks, on a future program. But I want to thank you for taking time to be with us today.

Dr. SKOMAL: Oh, my pleasure. It's great to be here.

FLATOW: Have a good weekend.

Dr. SKOMAL: Yes, you, too.

FLATOW: Greg Skomal is a senior biologist in the Massachusetts Division of Marine Fisheries in New Bedford, Mass., and he was joining us by phone from there.

When we come back, we're going to switch to electric cars, plug-ins. Do you want a plug-in? How about a Chevy Volt or a Nissan Leaf? We're going to compare the two. Maybe you could talk to us about what you'd like to see the perfect plug-in to be. What would you are these two cars the kind you might purchase? If not, what do you want to have?

Our number, 1-800-989-8255. You can tweet us @scifri, @-S-C-I-F-R-I, or go to our website at sciencefriday.com, where you can chat around with some folks that way.

So stay with us. We'll be right back after the break.

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FLATOW: I'm Ira Flatow. This is SCIENCE FRIDAY from NPR.

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