“The finning of sharks for shark fin soup is a horrible activity. It is the equivalent of cutting off the hands of a monkey in the jungle and then turning him loose. Of course that could never happen, because such atrocities on land are more visible than those that take place at sea. Much of the ocean is out of sight out of mind, and that is why the efforts of Shawn Heinrichs and others to bring shark finning to the public’s attention is so important.”
– Bill Shedd – AFTCO President
At a fishery in Kesennuma, Japan, hundreds of salmon sharks are lined up, weighed and then their fins are sliced off.
Shawn Heinrichs, one of today’s premiere underwater photographers/cinematographers, was recently featured in one of HDNet‘s Dan Rather Reports segments titled, “All for a Bowl of Soup”. Shawn’s investigative report has produced one of the most disturbing, yet insightful looks yet into the Asian shark fin markets. The evidence captured on film gives viewers a perspective on the death and destruction of shark populations in a way that has likely never been seen before:
* hundreds of bags labeled as “Anchovies from Mexico” overflowing with shark fins
* 6,000-7,000 fins – one day’s haul in just one shop – being sorted, washed and dried
* sharks being finned alive on fishing vessels, then dumped back into the ocean to drown
* a “tuna fishery” that processed less than 100 tuna, yet thousands of sharks – which were caught “accidentally” as by-catch
* a finned nurse shark, still alive, slowly dying on a reef – within a marine sanctuary off Indonesia
If you wish to gain a new perspective on the horrors of shark finning and develop an understanding of the unsustainable destruction that shark populations are experiencing on a global level, then please watch the 7-minute video below (the full 30-minute segment can be downloaded from iTunes, search “Dan Rather: For a Bowl of soup”.
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This article was originally published by EurekAlert! global news service.
University of Miami study shows alarming accumulation of BMAA neurotoxins in shark fins; may pose a threat to shark fin consumers
MIAMI – Sharks are among the most threatened of marine species worldwide due to unsustainable overfishing. Sharks are primarily killed for their fins alone, to fuel the growing demand for shark fin soup, which is an Asia delicacy. A new study by University of Miami (UM) scientists in the journal Marine Drugshas discovered high concentrations of BMAA in shark fins, a neurotoxin linked to neurodegenerative diseases in humans including Alzheimer’s and Lou Gehrig Disease (ALS). The study suggests that consumption of shark fin soup and cartilage pills may pose a significant health risk for degenerative brain diseases.
“Shark fins are primarily derived through finning, a practice where by shark fins are removed at sea and the rest of the mutilated animal is thrown back in the water to die,” said co-author Dr. Neil Hammerschlag, research assistant professor of Marine Affairs & Policy and director of the RJ Dunlap Marine Conservation Program (RJD) at UM. “Estimates suggest that fins from as many as 70 million sharks end up in soup. As a result, many shark species are on the road to extinction. Because sharks play important roles in maintaining balance in the oceans, not only is shark fin soup injurious to the marine environment, but our study suggests that it is likely harmful to the people who are consuming them.”
Seven species of shark were tested for this study: blacknose, blacktip, bonnethead, bull, great hammerhead, lemon, and nurse sharks. Samples were collected from live animals in waters throughout South Florida.
“The concentrations of BMAA in the samples are a cause for concern, not only in shark fin soup, but also in dietary supplements and other forms ingested by humans, ” says study co-author Prof. Deborah Mash, Director of the University of Miami Brain Endowment Bank. The Bank supports basic and clinical research and holds one of the world’s largest collection of postmortem human brains encompassing a wide range of neurological disorders. In 2009, Prof. Mash and her co-authors published a study in the journal Acta Neurological Scandinavica, demonstrating that patients dying with diagnoses of Alzheimer’s Disease and ALS had unusually high levels of BMAA in their brains up to 256 ng/mg, whereas normal healthy aged people had no BMAA, or only trace quantities of the toxin present. “BMAA was first linked to neurodegenerative diseases in Guam, which resulted in the progressive loss of structure and function of neurons.”
The shark study found a similar range and even higher BMAA in the fins tested. The new study found levels of between 144 and 1836 ng/mg of BMAA, which overlapped the levels we measured in the brains of Alzheimer’s and ALS victims. Surprisingly, this level fits with the BMAA levels in fruit bats examined by Paul Cox, animals which concentrate BMAA from their diet of cycad seeds. He linked ingestion of fruit bats to the severe ALS/Parkinsonism dementia that afflicted many people in Guam.
“Not only does this work provide important information on one probable route of human exposure to BMAA, it may lead to a lowering of the demand for shark fin soup and consumption of shark products, which will aid ocean conservation efforts,” added Hammerschlag.
Guy Harvey & tiger shark – Bahamas. Photo courtesy of Neil Hammerschlag.
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Responding to last week’s announcement from the Government of the Bahamas that it will prohibit all commercial shark fishing in its more than 240,000 square miles of territorial water, Dr. Harvey commented: “I am very impressed and pleased that the Government of the Bahamas has taken the necessary and correct step to further protect its marine resources from over-exploitation by both local and foreign interests. This new legislation compliments the ban on commercial long line fishing enacted 20 years ago. The ban on commercial shark fishing and exportation by shark by-products is a huge step in the conservation of sharks worldwide.”
Through the Bahamas National Trust (BNT), Dr. Harvey met with government officials last March to add his voice and influence as a highly respected conservationist to call for strict regulations to ban the commercial fishing of all sharks in The Bahamas, an archipelago of 700 islands sweeping across 500 miles of open ocean. The Bahamas is the fourth country to ban shark fishing after Honduras, the Maldives and Palau. Estimates are that more than 70 million sharks are killed annually around the world.
One of the premier shark-watching destinations for divers, reeling in $800 million over the past 20 years for the Bahamian national economy, sharks, according to Dr. Harvey, were worth much more alive than dead.
“Many countries have seen their populations of sharks annihilated by commercial over-exploitation,” said Dr. Harvey. “Research has shown that shark populations do not recover. Other countries will take encouragement from the Bahamas’ very bold move. They are realizing, very quickly, the value of the living shark in maintaining the health of reef ecosystems. In addition, the economic value of a living shark to ecotourism is now widely accepted as a sustainable and non-consumptive use of a marine resource with many additional benefits to respective island nations.”
Last year, following news that a Bahamian seafood company was considering exporting sharks to the Far East, the BNT along with the U.S. based Pew Environmental Group and individual conservationists, such as Dr. Guy Harvey, who created a “Protect Bahamian Sharks” campaign logo and poster, initiated a petition drive to force the issue of banning commercial shark-fishing. The government upon receiving a petition signed by 5,000 Bahamian residents acted this week to protect the some 40 sharks species found in Bahamian waters.
With shark populations around the world continuing to spiral downward, marine scientists such as Dr. Guy Harvey, are working around the clock to give these magnificent animals a fighting chance for survival. Dr. Harvey is also seeding cultural change in the structure of shark fishing tournaments to creating Catch and Release divisions.
Last month, he brought his cause into the epicenter of one of the nation’s oldest and largest shark fishing tournaments in Ocean City, Maryland. Thanks in part to his efforts and a willingness to continue to adapt by the tournament founders and organizers, The Ocean City Shark Tournament’s cash and prize package payment in the catch and release division increased to over $15,000.
In May, the Second Annual Guy Harvey Ultimate Shark Challenge, a catch and release only tournament, was held on the West Coast of Florida in Punta Gorda. The tournament, created as a model for catch and release only shark tournament formats, drew some 3,000 competitors and spectators and paid out over $15,000 in cash and prizes.
In related shark conservation activity, Dr. Harvey offered his artistic talent and foundation sponsorship funding in support of the recent Circle Hook Symposium held in Miami. The symposium, hosted by the National Oceanic and Atmospheric Administration (NOAA), is an international gathering of scientists, resource managers and constituents convening to discuss the performance and use of circle hooks in commercial, recreational and artisanal fisheries. While it is legal to use a J-hook to fish for sharks, experts such as Dr. Harvey recommend using a circle hook, where the barb points inward and not outward.
The oceans just got a little safer for sharks, and conservationist, artist and scientist —Guy Harvey couldn’t be more pleased.
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On any given dive in the Cayman Islands the chances of encountering any species of shark are very slim. Why is this? The primary reason is that most of the large coastal and ocean sharks have been caught in the last fifty years by long line fishing efforts directed at tuna and swordfish and more recently at sharks themselves.
Nowadays, sharks are kept by such industrial fishing operations which remove the fins and sell them to Asian interests. Many species of ocean going sharks such as blues, tigers, hammerheads, makos, threshers and oceanic whitetip sharks pass by our islands and sea mounts, and have extensive ranges so are considered highly migratory species. These have been heavily fished by high seas long lining operators. Other species exhibit more site fidelity and have a home range such as the Caribbean reef shark and the blacktip shark, which are the species we are more likely to encounter here.
To the untrained, eye blacktips are similar to the reef shark at typically six feet long, with a large dorsal fin and black tips on the pectoral fins. They have a pointed nose and compact body built for speed. They can grow to eight feet and are found worldwide in tropical and subtropical waters. Blacktip sharks feed over continental shelves on schooling fish such as sardines, jacks and mackerels. On the Pacific side of Panama, I have filmed them feeding on green jacks and scads along with schools of yellowfin tuna and spotted dolphins. In South Africa, blacktips are major predators on the annual sardine run. In Florida, the blacktip shark and the similar looking spinner shark are common near shore predators of mullet, sardines and jacks, and they are frequently caught by anglers fishing from the beach.
Around the Cayman Islands, blacktips are found in the shallow sounds and flats bordered by mangroves, and are primarily fish eaters, but will also consume sting rays and crustaceans. There is a very narrow shelf area here, so the black tip sharks keep to the flats and back reef areas that provide the most food.
An Oceanic Whitetip Shark which ate a trolled bait intended for marlin. Photo Courtesy of Richard Gibson
In complete contrast, the oceanic whitetip shark (OWS) is found roaming the open blue water and rarely comes close to shore. In looking at their shape, you know they are designed for the open ocean habitat. They are large animals with robust bodies, typically about eight feet, but growing up to twelve feet long. They are characterized by their very long, broad pectoral fins, with blotchy white tips as with all their other fins.
They have been a primary target in the shark fin trade and now their populations may be as low as 1% of their pre-exploitation levels in the western Atlantic. They used to be the most abundant “large” animal (over 100lb.) on the planet. Found in all the world’s tropical oceans, typically they associate with flotsam and those species of fish that congregate around flotsam and with migrating marine mammals such as whales and dolphins. They are usually solitary and slow moving, conserving energy between meals which may be weeks apart. Often, they are accompanied by pilot fish and rainbow runners. They are very inquisitive and will investigate anything floating looking for carrion. Tiger sharks exhibit similar behavior.
The only time we see OWS is when we go fishing offshore looking for dolphin fish, tuna and marlin. They may be encountered around a school of dolphin fish and rainbow runners in association with a floating log or shipping pallet. Off Jamaica, I have seen OWS following pilot whales and sometimes spotted dolphins. During the recently held Cayman Island International Fishing Tournament, Oliver Dubock, a PhD student working with the DoE and Overseas Territory Environment Programme (OTEP), tagged two OWS (caught by anglers participating in the tournament) with electronic tags to learn more about their natural history and migrations. Knowing that this species spends a lot of time at or near the surface, the satellite tags will pin point their migrations around the Cayman Islands. More information will be forthcoming. We know very little about the life history of this species which is on the verge of extinction and is listed as “critically endangered” by the International Union for Conservation of Nature (IUCN).
Open water shark interactive dives, with this species, are safely conducted in the Caribbean and Bahamas without incident, in spite of their inquisitive nature and reputation. But divers are cautioned to interact with the OWS with extreme caution.
If you are diving, snorkeling or fishing and encounter one of these rare species, please call the Dept. of Environment and let them know the location, date, species, approximate size and sex. If you catch a blacktip or an ocean whitetip shark, then take the necessary measurements and photos as well as a tissue sample (fin clip) and then please release them alive.
It is our collective responsibility to conserve the marine environment and maintain the biodiversity of the planet.
Fish responsibly and dive safely.
— Guy Harvey
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Mahmood Shivji and Brad Wetherbee attach SPOT tag to tiger while Dr. Sam Gruber secures the shark
I recently joined Dr. Sam Gruber and his staff with the Shark Lab in Bimini to tag tiger sharks. We attached a satellite tag (SPOT -Smart Position or Temperature Transmitting) to the dorsal fin of a 9 foot male tiger shark caught off Bimini. This shark was named after a High School in Nassau called CV Bethel— As I follow up on my address to their assembly and to the ministers of the Bahamian Government. We named this shark after the school so the school children would be able to follow the migrations of “their” shark on a weekly basis. Shortly after we left, Dr. Steven Kessel and the shark Lab crew caught a 10 foot female tiger shark. She, also, had a SPOT attached and is named St. Mary, after another Nassau school. Mahmood Shivji and Brad Wetherbee will shortly be making these tracks available to the respective schools.
In addition, I was accompanied by film producer George Schellenger. We shot, for the tiger documentary, some amazing sequences with a great hammerhead and some interactions with Caribbean Reef sharks. No authoritative documentary on tiger sharks could be complete without a visit to the Bimini Shark Lab and some wise words from Dr. Gruber, who has worked in Bimini for more than two decades. The Guy Harvey Ocean Foundation is collaborating with the Bimini Shark Lab on a number of new projects.
By the way,the Bimini Big Game Club is looking great and is gearing up for a busy summer. Some mooring balls were being deployed while I was there, and the new restaurant expansion and deck was in full swing. Clients will be able to dine overlooking the crystal clear water below teaming with jacks, tarpon, eagle rays and bonefish.
The big game is definitely ON!
—Guy Harvey
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The stripy and pug-nosed tiger shark gets little coverage or respect in the world of media shark stories compared to the idolizing attention showered on species such white sharks and whale sharks. And when they do receive the occasional mention, tiger sharks bear the brunt of disparaging descriptors such as “garbage cans of the sea” just because a few individuals of the many thousands killed around the world have been found with indigestible, man-made objects such as a beer bottle, tin cans, chicken wire in their stomachs. Tiger sharks do indeed have broad diets and are opportunistic feeders, but the reality is they consume almost entirely their normal prey of fishes, turtles, marine mammals, and even large invertebrates. The discovery of man-made objects in their diet is rare, and it does a magnificent apex predator injustice to assume tiger sharks make a habit of wandering around near human population centers focused on scooping up our garbage that ends up in the sea. On the contrary, ongoing research being conducted at the Guy Harvey Research Institute and Guy Harvey Ocean Foundation (GHRI/GHOF) on tiger shark migrations is shedding new light on how remarkable and environmentally flexible these amazing sharks are.
An important requirement for the proper management and conservation of any shark species is a robust understanding of its migratory patterns, how it uses its environment, and identification of what is termed its “critical habitat” – areas that are key to successful reproduction and feeding. To understand tiger shark movements and aid in conservation efforts, the GHRI/GHOF in collaboration with the Bermuda Shark Project and with financial support from AFTCO is investigating tiger shark movements in the western North Atlantic in a long-term study. The sharks’ movements are being studied by employing satellite tags that relay information on where the tiger shark is and/or its depth in the ocean.
What have we found so far?
Sharks that we outfitted with satellite tags in Bermudian waters are providing exceptional information about their long-term migratory behavior. We have been fortunate to be able to follow these tiger sharks for a record length of time (12-17 months and counting), and are discovering fascinating information about their seasonal movements. The migratory tracks of two sharks are shown as examples. Please visit the GHRI web site: http://www.nova.edu/ocean/ghri/tshark.html to see long-term tracks for other tiger sharks.
In brief, the sharks left Bermuda in the fall of 2009 as the waters cooled and made notably direct pathways to the Bahamas or Caribbean, where they spent 6-8 months in close association with island habitats. Then starting in the spring of 2010, the tiger sharks reversed course showing highly directed migrations northwards, moving beyond and often east of Bermuda and staying well out in the open ocean. In two instances, the batteries on the tags have lasted over 17 months and have revealed a consistent migratory pathway back to the Bahamas starting in the fall of 2010. What is also amazing is that after their pelagic sojourn these sharks have returned to locations in the Bahamas really close to where they were hanging out a year ago! Who gave them a GPS?
These migratory patterns makes one wonder what the sharks are doing so far out in the Atlantic Ocean after spending approximately half a year acting like reef sharks tightly associated with island habitats in the Bahamas and Caribbean. Something must be seasonally attracting these sharks into the deep open-ocean far offshore. We’re guessing it is not indigestible man-made garbage. Are they out in nearly the middle of the north Atlantic for 2-4 months for mating? For feeding on migratory prey such as turtles? It’s still an open question. Notably, however, these tiger sharks are displaying a remarkable ability to drastically switch their habitats comfortably, using shallow, coral reef environments for part of the year and completely open-ocean, deep environments for the other part with rapid travel in-between. Few other shark species show this flexibility in the habitats they can use.
Based on these initial but novel findings, we are continuing this study in additional places to get a more detailed picture of tiger shark movements in different parts of the world. Our hats are off to these stripy, majestic fishes for their astonishing migratory abilities!
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I used a couple of spare days I had between Christmas and New Year to visit Tiger Beach on Little Bahama Bank and deploy some more SPOTs on tiger sharks. My team went on board the “Shear Water” with Jim Abernathy who has been diving this site for twelve years on a weekly basis. In addition to the tagging team of Dr. Mahmood Shivji (director of the GHRI) and Neil Burnie of the Bermuda Shark Project, we were accompanied by film maker George Schellenger who is in the process of finishing up an exciting and educational documentary featuring Jim, Wyland and myself interacting with the sharks at Tiger Beach.
Both Wyland and I got some great photos of the Tiger Shark on our trip together
Along for the expedition were my son Alexander, who has assisted me in the Bermuda Shark project, but had yet to dive with a tiger. GH staffer Jay Perez also had his first visit to Tiger Beach as did Ollie Dubock an, English PhD student working on sharks in the Cayman Islands.
There were several things to accomplish. We were able to catch and tag four tiger sharks between 9 and 11 feet long, three females and one male. Most of the tiger sharks we tagged in the last two summers in Bermuda were males. The vast majority of the sharks Jim sees at Tiger Beach are females. We want to find out why there is such a huge difference in the distribution of the sexes. No one knows where tiger sharks breed.
We caught two sharks about 5 miles south of Tiger Beach, one of them at night. The other two were caught at the famous dive site. Jim had checked out these individuals first to make sure they were not one of his “players” or sharks that he sees on a regular basis, and to be sure we wanted to tag the “transient” animals. All sharks were caught on heavy rope and using cable leader and 20/0 circle hooks with the barb filed off. They were handlined into the swim platform and secured on top of the platform with most of their body in the water, breathing normally while Neil deployed the SPOTs in quick time. It took between 7 -10 minutes to tag these huge animals and set them free. Jim and his crew members Jamin, Matt and Brian, were awesome in assisting the catching process and were delighted to be doing something different with these animals. Thanks again team for taking some of your vacation time to assist us with the tagging effort. We were lucky with the weather, and had a successful expedition.
Film maker George Schellenger was busy shooting everything with help from Alex, Jay and me to fill out his own documentary but also shoot more footage for my comprehensive documentary on the natural history of tiger sharks. This is approaching completion and I am just waiting on another cycle of tracks to come in before I can wrap up the story.
George plans to use his documentary to educate the government and people of the Bahamas about the value of a living shark (shark interactive programmes bring over $50 million dollars per year to the country’s economy) and to encourage them not to allow commercial fishing for shark fins by local or foreign companies. Permitting this kind of extraction would annihilate the last strong hold for sharks in the north western Atlantic. This has been the case in so many other countries, but island nations now becoming involved in protection of sharks and promoting shark interactive programmes for tourism and research are having big success stories.
Fish responsibly, dive safely. Happy New Year.
— Guy Harvey
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There has been a lot of news in the realm of marine conservation over the past couple of weeks – some good, some bad, and some downright ugly! Here are some of the more interesting:
The Good:
Longlining Outlawed in Panama – Terry Andrews of famed Tropic Star Lodge in Pinas Bay, Panama is reporting that Panamanian President Ricardo Martinelli has signed Executive Decree 486, which immediately prohibits all forms of commercial and industrial longlining in all of Panama’s jurisdictional waters! Fishing boats of 6 tons are less will still be allowed to longline, but only with a strict license and only in designated areas. For more information about Tropic Star Lodge and big game fishing in Panama, read Guy’s latest book, Panama Paradise: A Tribute to Tropic Star Lodge.
Shark Conservation Act Signed into Law – this is great news that seems to have received very little coverage. On January 4th, President Obama officially signed the SCA into law. The law closes a loophole which allowed U.S. flagged vessels to buy shark fins on the open sea for the purpose of reselling them in U.S. markets for a rich profit (the act of shark finning has been outlawed in U.S. waters since 2000). The SCA also allows for sanctions to be out on other nations whose own shark fishing regulations are not consistent with those of the U.S.
The Bad:
Guy's latest artwork on the Bluefin Tuna
Tuna Fetches Record Price – A 754-pound pacific bluefin tuna caught off the northern coast of Japan sold for a record price of almost $396,000 (U.S.) in a Tokyo seafood market in early January. That works out to around $526 per pound! This is very bad news for a species whose stocks are already severely depleted by commercial fishermen who are trying to meet the overwhelming demand worldwide for sushi. With prices like this, will we see more fishing fleets going after pacific and atlantic bluefins? Let’s hope not…
The Ugly:
Gordon Ramsay Attacked by Gang? – Celebrity chef Gordon Ramsay claims to have been doused in gasoline and held at gunpoint during two different incidents in Costa Rica while trying to document Taiwanese gangs that engage in the illegal shark fin trade. Ramsay said he witnessed thousands of fins drying out at gang hideouts, and later saw a bag of fins tied to the keel of one of the gang’s fishing boats.
— Guy Harvey
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The Guy Harvey Ultimate Shark Challenge is shown here as seen on the NBC Nightly News with Kerry Sanders. This effort supported by the Guy Harvey Ocean Foundation encourages the release of all sharks and involves a satellite tagging component to help determine shark movements.
For a complete list of our other featured blog posts and to see the full line of Guy Harvey Sportswear, please visit: www.guyharveysportswear.com
For the longest time after the 1975 blockbuster “JAWS” gave us a spine-tingling ride, there was an often used saying that “the only good shark is a dead shark”. This man- against-beast thriller and its many progeny shark horror flicks still pervade the public’s psyche, anointing all sharks as human-eaters and keeping many beach-goers out of the ocean.
The public and media’s morbid fascination with sharks as killing “machines” continues today. There is a steady stream of media coverage when fishers catch and drag back a large shark for photo-ops. In some minds, catching and killing a large shark is almost heroic and fashionable, and a testament to man’s superiority in the “battle” against the beast.
Meanwhile, the enormous toll taken on shark numbers worldwide due to indiscriminate fisheries continues unabated. All this shark killing causes some to wring their hands in anguish about longer-term ecological impacts. Others say “what’s the big deal if sharks are killed?”
Who’s right? Should we care if many of the oceans large sharks are exterminated? Is there really enough of an impact on the marine environment to worry about?
New studies show that sharks also influence the behavior of their prey. Photo credit: B. Watts
It seems intuitively reasonable that sharks, as top-level predators, play an important role in maintaining stability in the ocean’s food chain. Most people objectively or “in their gut” understand that life on earth is a series of complex interactions, with connections through food webs. Simply put, species at the top of the food chain eat species in the middle of the food chain which in turn eat species on the bottom of the food chain. And therefore, changes in the abundance of one community segment will affect the other segments. In fact, recent studies have indeed documented that overfishing of large sharks (the apex predators) has resulted in numerical increases in populations of their normal prey such as smaller sharks and rays (known as mid-level predators or mesopredators) in a phenomenon called “predator release”. In turn, the mesopredators are overeating their own smaller prey such as bay scallops and bony fishes even lower on the food chain. Scientists call such effects that ripple down the food chain “trophic cascades”.
Still, will it really matter all that much if we overfish sharks? Won’t some other large predatory species, such as billfish and barracuda, take over for sharks at the top of the food chain and keep the food webs functioning normally?
If only the interconnections of life were that simple…….
New studies in Shark Bay, Australia by Dr. Mike Heithaus and his team at Florida International University are showing that in addition to playing important roles in the food web by direct predation (or lethal) effects, including keeping prey population sizes in check, sharks also play a large role in maintaining the normal functioning of marine ecosystems by— get this— influencing the behavior of their prey!
How does this prey behavior to ecosystem function connection work?
Let’s take the seagrass ecosystem as an example. Recreational fishers and patrons of the marine outdoors know that seagrass beds are critically important nursery areas for juveniles and sometimes even adults of all types of fishes and invertebrates. The health of seagrass ecosystems is woven into an intricate balance with larger animals such as sea-cows, sea turtles and birds that obtain their sustenance in seagrass beds, either by directly grazing on the seagrass or eating smaller creatures living on the seagrass or in the surrounding sediment. These large animals (mesopredators) are in turn, prey for tiger sharks.
Let’s connect the ecosystem dots: Dr. Heithaus and colleagues have documented that sea-cows, sea turtles and birds avoid hanging out in seagrass beds when tiger sharks are seasonally present in Shark Bay, and jump right back in to devour their favorite foods after the sharks leave in winter. Makes survival sense doesn’t it? What this shows is that the presence of tiger sharks causes the mesopredators to change their habitat-use behavior to avoid the risk of being eaten. And this risk-avoidance behavior keeps the seagrass beds and their inhabitants from being over-consumed.
The take home message is that sharks keep the marine ecosystem in balance not just by directly eating their prey — the role that gets the most attention, but also indirectly by altering the behavior of their prey. The importance of this indirect ecosystem role of sharks is just beginning to be recognized.
We at the Guy Harvey Research Institute, Guy Harvey Ocean Foundation and AFTCO hope that you will keep in mind the delicate balance required to keep our oceans healthy. Please enjoy our marine environment with respect for all of its remarkable life forms. If you catch a shark, enjoy its magnificence, keep its important ecosystem role in mind – and let it swim away.
For a complete list of our other featured blog posts and to see the full line of Guy Harvey Sportswear, please visit: www.guyharveysportswear.com
I would like to welcome you to the Guy Harvey Sportswear web site. Here we will feature my blog where I will report on expeditions, adventures, and various marine conservation efforts. We will also include various guest bloggers, videos and photos that I believe you will find interesting, whether you are a serious fishing or diving enthusiast, or simply someone who cares about the marine resource, loves living the coastal lifestyle, or just wants to learn more about Guy Harvey sportswear.
I would like to welcome you to the Guy Harvey Sportswear web site. Here we will feature my blog where I will report on expeditions, adventures, and various marine conservation efforts. We will also include various guest bloggers, videos and photos that I believe you will find interesting, whether you are a serious fishing or diving enthusiast, or simply someone who cares about the marine resource, loves living the coastal lifestyle, or just wants to learn more about Guy Harvey sportswear.
