Last fall, a tour company in Australia stumbled upon a rare find: a dead whale. But what they had spotted turned out to be even rarer than that, as the video footage captured both sharks and a large saltwater crocodile tearing at the carcass—something no one had ever seen before.
It was an exciting enough observation to catch the attention of Austin Gallagher, chief scientist and CEO of Beneath the Waves. “I saw the post online on Facebook,” he told me, where it had already gone somewhat viral.
A seascape of fear? New study suggests fear of sharks shapes ecosystems. Photo Credit: Narchuk/Shutterstock
It’s kind of incredible how our fears can shape our behaviors. When Jaws was released in 1975, it fundamentally changed how we interact with sharks. In the years that followed, we hunted these large marine predators more intensely, and came to view them as terrible monsters—attitudes scientists still fight to this day. But while our fears are largely unfounded, there are lots of species that have good reason to be wary of these awesome fish. Scientists have now discovered that such fear can ripple through the reef ecosystem, impacting community structure all the way down to seaweeds.
There’s no doubt that sharks can be a bit terrifying, especially if you’re a snack-sized fish. Scientists have long suspected that such fear can alter behavior. Just like people that are scared of sharks avoid beach vacations, preyed upon fish might try to avoid areas where sharks roam in the hopes of steering clear of those sharp, pointy teeth. And where the fish avoid, the species they eat proper, a marine version of ‘when the cat’s away, the mice will play.’ Thus by creating landscapes of fear—or, in this case, seascapes—sharks could shape entire ecosystems even if the amount of prey they actually consume is negligible.
Not only do we not know how fear of sharks might shape marine habitats, our overall understanding of how sharks interact with other species is lacking. Despite our annual fin-fests and obsession with these fearsome fish, “we still only have a very basic understanding of their ecological roles in nature,” said Doug Rasher, a senior research scientist at Bigelow Laboratory, in a press release. So he and his colleagues decided to look a little closer, zeroing in on the impacts of sharks on shallow reef habitats off the coast of Fiji.
A diagram of the shallow lagoons studied. Figure 1 a and b from Rasher et al. 2017.
The well-lit, shallow lagoons of Fiji’s largest island, Viti Levu, are ideal habitat for tasty seaweeds like Turbinaria conoides, a favorite of herbivorous fish. Since the islanders established a no-take reserve protecting the fringing reef of Votua Village, Korolevu-i-wai, in 2002, the abundance of seaweeds has dropped dramatically, particularly in the more isolated back reefs, making room for corals to rebound. But not all areas of the lagoons are equally seaweed-free. The algae remain in the shallowest reef tops. Rasher and his colleagues wanted to understand why.
The research team put GoPros in the water to observe which fish were eating algae as well as when and where sharks were moving around the lagoons. They also surveyed for the presence of algae-eating fish during high and low tides, and to determine seaweed location and abundance. In addition, they calculated fish feeding rates on algae in shallow and deeper back reef areas during different tidal phases by deploying measured amounts of algae for the fish to snack on.
When they brought all that data together, a clear pattern emerged. The biggest predators like blacktip reef sharks (Carcharhinus melanopterus), whitetip reef sharks (Triaenodon obesus,) and tawny nurse sharks (Nebrius ferrugineus) only entered the back reefs when tides were high—the researchers estimated that on average, each 40 square meter section of backreef is trawled by 4 to 5 reef sharks and 1 jack during each high tide. And when that happened, the herbivorous fishes like unicornfishes (Naso lituratus and N. unicornis) pretty much stopped eating and disappeared, presumably steering clear of the meandering predators.
That meant that the shallow reef tops received very little attention by the algae-eaters, as they could only be accessed when the reef sharks entered the shallows to feed. And in turn, those reef tops sported about 20 times the amount of seaweed. The researchers ruled out the possibility that these algae just do better on the reef tops for other reasons, like increased amounts of light, by comparing the growth rates of caged weeds in both areas. So the stark difference between the tops and deeper troughs in the backreef appears to be driven mostly by the fish’s fear of sharks.
A 2013 study in Shark Bay, Australia, had similar results, finding the risk of tiger shark predation affected the nature and abundance of seagrasses. Combined, they paint a much more interesting picture of the role sharks play in marine habitats. Their effects go far beyond what they consume directly, so their mere presence can “actually shape the way [an ecosystem] looks and functions,” explained Rasher.
On the practical side, these results suggest that we might be able to reduce our fishing impacts by taking this kind of thing into account. “Our example highlights the need to consider predator effects in ecosystem-based management,” the authors write in their conclusions. “With knowledge of predator movements and resultant herbivore migrations, resource managers could mitigate this negative human impact in similar ecosystems by regulating not only where but when herbivores are harvested.”
And ultimately, they underscore the need to better understand the ecological importance of sharks and other large predators. “Large apex predator sharks as well as the large mesopredator reef sharks studied here are now generally rare or absent on coral reefs exposed to heavy fishing pressure; thus, the effects we documented may already be extinguished from many places,” the authors write. “Despite these difficulties, we need to study Earth’s remaining wild places where predators still abound, and capitalize on chance events and variability in nature… Only then can we understand the ramifications of predator loss or recovery.”
Citation: Rasher et al. 2017. Cascading predator effects in a Fijian coral reef ecosystem. Scientific Reports 7, 15684. doi:10.1038/s41598-017-15679-w
Sharks are pretty incredible animals. They’ve lived on this planet for more than 400 million years, and in that time, come to dominate the oceans they inhabit. That kind of survival when so many other lineages have gone extinct requires serious resilience. Now, a lemon shark off Florida has shown off just how tough these animals can be: he survived for at least 435 days with a hole in his body created as he shoved a swallowed fishing implement out of him through his flesh. Continue reading “Shark Survives Over A Year With A Hole Between Its Stomach And The Sea”
This is a guest post by Jake Buehler, who just so happens to be an AAUS certified scientific diver as well as a science writer based in the Seattle area. He blogs over atSh*t You Didn’t Know About Biology, which is full of his “unrepentantly celebratory insights into life on Earth’s under-appreciated, under-acknowledged, and utterly amazing stories.”
Summer is finally here in the Northern Hemisphere. The days are long, the weather is warm, and the water is inviting. It’s also time for our annual lesson from popular culture that this refreshing invitation is a lie, and that the only thing the sea offers us is electric, blinding terror. Yes, summer inevitably means the advent of a new crop of shark-based survival horror flicks.
This summer, much like the last with “The Shallows”, movie-going audiences will be treated to another shark-centric screamfest: “47 Meters Down.” The British-American film—starring Mandy Moore and Claire Holt—opened in U.S. theaters last weekend. Recent, somewhat ubiquitous trailers for the film outline its terrifying premise: while vacationing in Mexico, a pair of sisters goes cage-diving with great white sharks, only to have the winch suspending their protective cage fail, sending them plummeting 47 meters down to the ocean floor, from where they must escape to the surface before the swarm of sharks—or their dwindling air supply—does them in. It is no doubt that just like with “The Shallows”, we will again be reminded that the persistent blood lust of horror film sharks is altogether different from what science tells us about the behavior of their real-life animal counterparts. But the film and overall premise of “47 Meters Down” commit a litany of science inaccuracy sins completely unrelated to sharks. Frankly, the movie fails spectacularly when it comes to portraying the biology and physics at play during SCUBA diving (which is kind of amazing, actually, considering how much of the film’s plot is directly rooted in the consequences of being underwater). Being a trained AAUS scientific diver, dive science is an area I know a little about, so I made the commitment to sit through “47 Meters Down” so you wouldn’t have to, all to separate the reality of how diving works from…well, whatever it is that the movie plopped out.
Experts urge for more signs like this and other effective ways of protecting beachgoers. Credit: Shutterstock
Given the enormous backlash to Western Australia’s ill-conceived shark cull last year, you would think that government officials would have come to realize that killing sharks is a terrible way to respond to shark bites (more than 100 shark scientists and 2/3 of Western Australians opposed that cull). But it appears that authorities in North Carolina have not learned from others’ mistakes: Oak Island Town Manager Tim Holloman announced this week that following two life-threatening bites, officials would “take appropriate action” and “eliminate” any shark they deem a potential threat. According to the L.A. Times:
If officials see aggressive behavior from any sharks near shore, such as darting in and out of the surf line or coming within about 100 feet of the beach, Holloman said, the officials are prepared to euthanize the animal.
“If they look like they’re posing a danger, we will authorize that action,” Holloman told the Los Angeles Times.
Let me be extremely clear: what happened to the two teenagers in Oak Island, N.C. this week is awful. My heart goes out to them and their friends and relatives. They have survived something terrible and life-altering, and I hope that they are being well supported and cared for. But killing any shark that comes within 100 feet of shore or displays “aggressive behavior” will not return their limbs — nor will it prevent anyone else from losing theirs. Continue reading “Hey Everyone (Including North Carolina): STOP RESPONDING TO SHARK BITES BY INDISCRIMINATELY KILLING SHARKS.”
Shark Week is over, and as the week has progressed, the flood of negative press about Discovery’s favorite time of the year has weakened to a trickle. Instead, news organizations are talking about how well Discovery did this year in spite of the backlash. Shark Week “set records” say the headlines, and it’s no shock: given the increased sponsorship and the two-hour uptick in programming, Shark Week 2014 should have beaten 2013 with its fins tied behind its back. But guess what? It actually didn’t.
Discovery’s done just about all they can to spin the past week positively. “The King of Summer reigned with Discovery earning its highest-rated SHARK WEEK ever in its 27-year history,” begins Discovery’s most recent press release. The statement is so bold and so confident that one might miss the phrase “across several key demos” which immediately follows. A closer examination of the release reveals that the “good news” is riddled with caveats, in stark contrast to 2013’s version, which unabashedly bragged about being “the most-watched SHARK WEEK in the event’s 26 year history across all key demos” (emphasis mine). And even 2013 was trying to trump up the facts—it was only the second most-watched Shark Week ever in terms of total viewers.
The hard numbers are simple. In 2013, Shark Week drew in an average of 2,106,000 viewers during primetime programming. In 2014, Shark Week only garnered 6,000 more, even though they had 2 more hours of new specials and increased PR. In their key age demographic—18 to 49 year olds—there were 68,000 fewer viewers on average during primetime. Even if you look at the entire day, this year didn’t do better. In 2013, the total-day average for Discovery during Shark Week was 1,048,000 viewers—in 2014, that dropped to 1,035,000. Overall, it was only the third best Shark Week to date with 42 million total viewers, behind the 62.1 million viewers that tuned in for 2010 and 51 million viewers that watched in 2013. A 9 million viewer drop is not insignificant, especially when you have 2 more hours of time that you’ve produced to draw them in.
Discovery highlights the few ways that 2014 did better—but a straight up comparison shows it struggled.
If you compare 2013 and 2014 Shark Weeks by day and time slot, a pattern emerges. Let’s start with Day 1: Sunday night is Discovery’s kick-off evening, and it was the night that Discovery aired the notorious Megalodon mockumentary last year. The fake footage seen round the world reeled in 4.8 million viewers, a good chunk of which then took to Discovery’s Facebook and Twitter to complain. Discovery decided to ignore the strong pushback and began 2014 on a similar note with Shark of Darkness, another 2 hour special focusing on a legendary shark that doesn’t existusing made-up events and fake footage to sell the story. Fool us once, shame on you, Discovery. Try to fool us twice, and you’ll net one million fewer viewers.
The rest of the week, Discovery was mostly unable to keep up with 2013’s viewership. Though the Shark After Dark talk show fared slightly better in 2013 (up 3%, according to Discovery), most of the programming lost little or lost big. The one notable exception was Alien Sharks 2, which netted more than 340,000 more viewers than the 2013 program that shared its timeslot, Spawn of Jaws. As the most science-based program of the week, Alien Sharks not only didn’t play into the fear-based hype of programs like Sharkageddon, it was the only show that didn’t focus on big, “scary” sharks (in other words, it was the only show that focused on the sharks that make up the vast majority of shark species).
Discovery’s viewers voted with their TVs, trying to send a clear message that science-heavy programming is what they want. That message is even clearer when you compare how the original Alien Sharks from 2013 did against the program in its time slot: Sharkageddon, arguably the most unscientific, fear-based program that Discovery Shark Week has ever created. Even with the hyperbolic title and promise to explain ‘the recent spike of shark attacks in Hawaii,’ Sharkageddon only drew in 2.4 million viewers, making it one of the least-watched programs of the year—over 700,000 viewer less than the same day and time reeled in last year with Alien Sharks.
But perhaps the most impressive PR spin was Discovery’s packaging of Shark Week’s social media coverage. Discovery was quick to point out that Shark Week “generated 70 primetime Trending Topics on Twitter over 7 days” and that “13 million people had more than 21 million interactions” on Facebook “marking the strongest year ever online”. Never mind that the Twitter buzz they bragged so much about was way down from last year according to Upwell—Discovery also glossed over the fact that the sentiment of this conversation was far from positive. A shocking 40% of social media mentions of Shark Week were negative, while an embarrassing 11% were positive, a recent analysis by the social media monitoring company Sysomos shows.
I guess Discovery is hoping that any social media mention is good social media mention? Image from Sysomos’ Blog
Discovery claimed their new approach to programming (read: fear-driven and fake) was designed to “appease a different audience”. Instead, they’ve pissed off a large chunk of their current one, and there’s no evidence that this new and different demographic is tuning in.
Not that Discovery is paying attention.
“Everyone is absolutely thrilled,” Michael Sorensen, Discovery’s vice president of development and production, told The LA Times just this week. “It shows you how engaged the ‘Shark Week’ fans are as we keep making it bigger and bigger.” I guess if by “engaged” he meant “outraged”, then perhaps Michael has a point. Shark Week fans are ‘engaging’ more and more through social media, telling Discovery just how little they appreciate the way they are lied to and manipulated. But the more Discovery ignores their comments, tweets, and posts, the less they will ‘engage’ at all.
So what will happen to Shark Week?
It’s hard to say. Discovery’s audience has tried to let them know that science trumps fear, and they’re sick of the same old ‘sharks are scary’ schtick. Yet at the same time, Discovery is going to find it’s hard to make science-based documentaries considering that Discovery has made a habit of betraying scientists’ trust, which means fewer and fewer will be willing to take the risk of working with them in the future. Besides, those scientists will be too busy fighting the array of myths about sharks that Shark Week has created to film incredible TV programs, especially considering that for all their talk of conservation, Shark Week doesn’t increase donations to shark research or conservation efforts (“It’s not easy to get people to rally around a creature that they’re conditioned to be afraid of” explains shark biologist Chris Lowe).
Meanwhile, Discovery seems hellbent on pretending that there’s nothing wrong on either front.
So my prediction? Shark Week 2015 will be even worse than 2014. There will be “more hours!” that will include more faked footage, more actors or waitresses portrayed as scientists, more fear, more hype, and more hyperbole. Discovery will continue to bluster on about how awesome they’re doing while scientists shake their fists and viewers do the only thing they can do to be heard: change the channel. We’ll just have to see if, after next year, Discovery will listen to them.
Tonight kicks off Shark Week, the longest-running television event in history. As readers of this blog know, many scientists (myself included) have become critical of Discovery’s beloved television event, criticizing their PR tactics, shark attack fearmongering, and overall lack of facts, science and conservation throughout the week.
Though the concerns have been brewing for the past decade or so, last year’s ‘documentary’ on C. megalodon shoved the Shark Week science—or lack thereof—into the national media spotlight. Discovery believes they did nothing wrong with presenting “one of the most debated shark discussions of all time“, however, scientists and viewers alike protested loudly about the special on and offline to the point that CNN and other major news stations covered the controversy. Supporting the notion that ‘any press is good press’, last year’s Shark Week was the most viewed of all time.
@WhySharksMatter we have more hours than ever before and most are the factual ones you enjoy.
This year, Discovery claims they have responded to the strong public and media backlash. Laurie Goldberg, executive vice president of public relations for Discovery, tweeted to explain that concerns over the scientific content of this year’s Shark Week are unfounded, as “most” of the programming is fact-based. Curious if that is true, I pulled up Discovery’s day-by-day plan and examined the shows’ descriptions. I categorized them as ‘science-based’ or ‘fear-based’ using the wording in the description and whether it mentioned scientists or research (particularly as the ‘host’ or focus). I then tweeted my predictions (Storify below). Here’s the summary table:
The smiling family and their catch—a large great hammerhead. Photo from MarktheShark.com
This past week was supposed to be a happy week for Rosie O’Donnell. She was ecstatic to announce that she’s re-hooked her old job on The View, and will be joining its cast next year. But instead, Rosie is being scrutinized for a different catch—one made two years ago.
In early 2012, photos began circulating of Rosie with Mark the Shark, a notorious fisherman who pompously claims he has killed over 100,000 sharks. Dangling in the foreground is a great hammerhead, the largest of the hammerhead species and one listed as endangered on the IUCN Red List since 2007 (prior to that they were ‘data deficient’). Rosie was immediately and loudly criticized for the act, as the species had newly become protected under Florida law.
Rosie did not respond well to the critique. “chill people – really – my family fishes” she tweeted to those calling for an apology for her actions. In response to one tweeter, she classily replied “it was years ago asswipe – b4 they were on the endangered list”. After the recent resurgence of the story due to a Slate article by widely acclaimed shark scientist and conservationist David Shiffman, Rosie stuck to her guns. “before hammerheads were illegal – my daughter caught one – end of story” she tweeted.
Or, to phrase her argument simply: the animals weren’t “endangered” when her family caught them, so back off.
@alexbvollmer – Alex when we caught the shark – hammerheads were not endangered – r u against fishing of all kinds
Last week, BuzzFeed published an article titled “19 Reasons Not To Go To The Beach This Summer.” In reality, the article contained only one reason—and as they hinted, it “rhymes with shmarks.”
— Katharine The Shark (@Shark_Katharine) June 21, 2014
We got it, BuzzFeed—we just didn’t think it was funny.
“Jokes” like this one (and the very real fear that BuzzFeed is “mocking”) are part of why so many shark species are declining or already threatened. The idea that sharks are dangerous, deadly, and otherwise unwelcome where we want to swim is devastatingly common. The pervasive, irrational fear of sharks isn’t something to make light of, particularly when such fear has real consequences for wildlife conservation. For example, the fear of shark attacks on beaches is what the Western Australian government used to justify implementing a massive shark cull that more than 100 shark scientists and 2/3 of Western Australians oppose. So far, the cull has cost over a million dollars and killed more non-target sharks than targeted ones, yet the government still plans to continue the cull for years to come.
Besides, if you’re going to make light of death at the beach, you should at least make it statistically valid. Maybe you should fear the beach—but not because of the Chondrichthyes beneath the waves. Sharks generally avoid people, and even when they don’t, the odds that you’ll be killed by a shark are unbelievably low. Since the 1500s, there have been less than 500 fatal shark attacks worldwide. Sharks kill less than five people every year globally and less than one person per year in the US. As the Dodo pointed out, there are far deadlier things to be afraid of.
Of the many reasons why beaches aren’t safe, sharks are the least of your worries. To show you what I mean, I present to you 19 beachy things that are more likely to kill you than sharks—in proper BuzzFeed form.
If you follow this blog at all, you know that this particularly pernicious “fact” is one of my biggest pet peeves. Why, you ask? Because it’s really not true. Completely, totally, 100%, proven-beyond-a-doubt false. And whoever decided to post this completely untrue statement just misinformed more than A MILLION people. Just look at how many favorites and retweets it got!
Perhaps even more importantly, if you simply take their own advice…
Come on, Google Facts! You can do better than this.
