These ruins are all that is left of the legendary Cabo Blanco Fishing Club, an exclusive resort for wealthy deep-sea fishermen who flocked there over half a century ago. Like Rick Rosenthal in Superfish, these men were on the hunt for “granders” — black marlin weighing in at over 1,000 pounds. Just a few miles offshore, the waters were so plentiful that sports fishermen didn’t bother trolling for their catch — they would simply throw their lines in the direction of the giant billfish they spotted from their boats. They called this place “Marlin Boulevard.” Back at the club, they celebrated their record hauls by lining the pathway with marlin tails and tossing back a drink at the bar.

Standing on this hillside, looking out at the water, one can still see the ocean currents that brought this bountiful sea life to Cabo Blanco. Up and down the coastline, dark blue waves meet a bulwark of lighter blue water. Here, the icy waters of the Humboldt Current collide with warmer water from the Pacific Equatorial Current. Where they meet, upwellings of cold, nutrient-rich waters bring millions of plankton to the surface. Anchovies feed on the plankton. In turn, the anchovies support a breathtaking array of undersea creatures, including squid, sailfish, marlin, swordfish, and shark. But at no point in time were the waters here as rich with life as they were during the heyday of “Marlin Boulevard” in the 1950s and 60s.

On a sunny day in August 1953, one of the Fishing Club’s founders, Texas oil magnate Alfred C. Glassell, Jr., was fishing eight miles offshore. Suddenly, there was a violent tug on his line — something had grabbed onto his five-pound mackerel bait. For nearly an hour and forty-five minutes, Glassell wrangled his catch. When it finally surfaced he saw just how enormous the creature was. Again and again the massive black marlin leapt from the water, trying to free itself from the hook. But it was no match for Glassell. At 1,560 pounds and over 14-and-a-half feet long, it was — and still is — the largest bony fish ever caught by rod and reel.

In the years that followed, game fishermen who heard of Glassell’s giant catch swarmed to Cabo Blanco to try their luck. Among the celebrities said to have visited are Jimmy Stewart, John Wayne, and baseball player Ted Williams. Ernest Hemingway spent several weeks there during filming for the movie adaptation of his book The Old Man and the Sea. He later wrote, “We fished 32 days, from early morning until it was too rough to photograph and the seas ran like onrushing hills with snow blowing off the tops.” According to the locals, Hemingway himself hauled in ten marlins. Five decades later, however, it’s sometimes impossible to tell fact from legend.

The Cabo Blanco Fishing Club has been closed for decades.

The Cabo Blanco Fishing Club has been closed for decades. Like these distant memories, the granders have also faded away from Cabo Blanco. In the years that followed Glassell’s record-breaking catch, a dramatic increase in the commercial fishing of anchovies, which are often used for fishmeal or bait, led to a significant decline in this important billfish food source. According to some, a particularly severe El Niño event in the Pacific likely compounded their scarcity. In 1970, the Cabo Blanco Fishing Club finally closed its doors, due to the military rule of General Juan Velasco Alvarado and the hostile environment toward North Americans his policies engendered. The giant billfish were gone, and so were the tourists.

Today, Peru’s commercial fisheries continue to harvest the sea. It is an endless process, driven in part by the poverty of seaside villages. Nearly one-fifth of the world’s total fishing catch comes from the Humboldt Current ecosystem, yet local fishermen make only pennies on the pound. Rick Rosenthal thinks our insatiable appetite for seafood is having dangerous consequences. In Superfish, Rick watches the fishermen unload their bounty on the docks. “It’s taken away by truck and put on a plane, and most of it going to the United States,” he explains.

In recent years, however, the Peruvian government has taken steps to prevent overfishing. In 1999, Peru’s maritime research institute, Imarpe, joined with the fisheries ministry to institute a satellite tracking system to help monitor the country’s entire fleet of fishing vessels. Boat owners foot the cost of renting the mandated equipment, which relays data about water temperature and salinity (to help identify the occurrence of upwellings) as well as information about the types and quantities of fish that are caught. All of the data is tracked by a central system, allowing the government to better manage temporary fishing bans and other sustainability measures. On April 2, 2008, Peruvian president Allan Garcia signed a Presidential Order that, effective immediately, will ban the commercial harvest of billfish in the country’s waters. Developed in cooperation with The Billfish Foundation, a Florida-based non-profit dedicated to conserving billfish populations, the plan also includes other conservation measures and promotes a sustainable, catch-and-release sportsfishing industry in Peru.

Many conservationists see sportsfishing as animal exploitation and thus oppose the practice outright. However, tourism generated by the sportsfishing industry in Peru could provide an economic boon that may help some in poverty-stricken coastal communities shake their dependence on commercial fishing, which many fear is irreversibly depleting the ocean’s ecosystems.

Time will tell if the government’s measures will help spur an ecological revival here. For now, however, the village of Cabo Blanco can only reminisce about its glory days long past.

In Superfish, Rick Rosenthal searches far and wide for the opportunity to swim with the greatest gamefish in the sea — billfish. Today, some marine ecosystems may be in jeopardy of disappearing. Tell the world what you think is worth preserving.

It may be unlikely that you’ve been lucky enough to come face-to-face with a “grander,” but we’re sure you have your own Super Sea Stories to share.

Do you have special memories of time you’ve spent at the ocean — or in it? Have you had a close encounter with marine life? NATURE wants to know about it.

Tell us your stories, and read those of other viewers, as we celebrate the world’s oceans and everything in them.

Read submitted stories — or submit your own in the comments field below.

Featured Viewer-Submitted Stories

“1985 I was the helicopter mechanic on a commercial tuna catching vessel sailing out of San Diego. We traveled the deep Pacific and the sights were incredible. I witnessed the fishing of all species of the ocean’s natural resources. Today we must try to stop the senseless slaughter of all the species in the ocean.”

– Gerard Shaughnessy, Nazareth, PA

“As a fishing guide in the East Cape region of the Baja peninsula, billfish, specifically striped marlin, play an integral role in the big-game fishing experience. I have always been captivated by how unique billfish are as an apex predator, enough so to chase them all over the world. My clients have always express their gratitude for having such an opportunity as to experience a billfish in its environment and the great satisfaction of releasing a healthy fish back into that environment…” Read more »

– Mark Daugherty, East Cape Guides, San Francisco, CA

“…Our tasks done we were getting ready to leave, suddenly … in the blink of an eye … there was a snap from an eerie deep green to pitch black. The lights were out! Mounds of herring pressed closely in on us. I was completely blind. No gauges, no buddy, not even my light was visible. I raised my light and pointed it straight toward my mask. The beam burst into a million mirrored reflections off the herrings’ scales. I took a slow deep breath and felt myself lift off the bottom and begin to ascend…” Read more »

– Phillip Stuart-Sharkey, Ocean View, HI

“Hi Bluewater Jon Schwartz here. I’m a big game kayak angler, and I travel all over the world to battle the ocean’s toghest predators — marlin, tuna, and shark- from kayaks. One story that may be of particular interest to you is that I caught and released 8 marlin from my kayak in 2 days this winter — with no help, other than getting a ride out to the fishing grounds…” Read more »

– Bluewater Jon Schwartz, Carlsbad, CA

“I work as a senior editor for Marlin magazine, which has taken me on journeys to various parts of the world in search of marlin and other billfish. Watching these creatures explode behind the boat, their power and grace, is just awe inspiring. What Rick and his team have done here, and the footage they’ve gotten from below, out of the fisherman’s viewpoint, only inspires me more. Fishermen are becoming more active on many fronts to conserve billfish stocks and help them expand to once-healthy levels. I hope that Rick’s project will get more anglers to release their catch. To Rick and your crew, well done!”

– Charlie Levine, Winter Park, FL

“My family spends a few weeks each summer in Provincetown, MA. Provincetown Harbor, which is filled with boats during the busy tourist season, is a wonderful place to kayak. Sea birds, horseshoe crabs, schools of small fish, big biting blue fish chasing thru the schools — everything.”

– BenInBrooklyn, Brooklyn, NY

“My story takes place a little over two years ago in the Bahamas. It was Mother’s Day weekend and my husband chartered a boat and captain to take us snorkeling. Within minutes of reaching the coastline, over thirty bottlenose dolphin surrounded our boat. I gently slipped into the water and I was encompassed by all but two very large guard dolphins who remained almost hidden. Almost immediately after I entered the water, I was approached by a dolphin that reminded me of…” Read more »

– Linda Carol, Weston, FL

“Congratulations to Rick and team on a wonderful project completed. I know you will all enjoy this film as it is not only truly honest in its approach but unique in its ability to bring together the distant trains of thought between fishermen and the general public. This is achieved through Rick’s great way with people and the natural world around him. The end result is a like-minded opinion on the need to protect our marine animals and enviroment. The footage is also first of its kind, unbelievable!! I’ll never forget working with the team from Superfish.”

– Captain Tim Dean, Calypso Fishing Adventures, Australia

“My story takes place a little over two years ago in the Bahamas. It was Mother’s Day weekend and my husband chartered a boat and captain to take us snorkeling. Within minutes of reaching the coastline, over thirty bottlenose dolphin surrounded our boat. I gently slipped into the water and I was encompassed by all but two very large guard dolphins who remained almost hidden. Almost immediately after I entered the water, I was approached by a dolphin that reminded me of an old, grandfather type persona. He was so close that I held my arms out in front so that he would not accidently bump into me. He looked directly into my eyes and I felt safe. I projected all of my positive energy out and through my fingertips. We remained like this for several minutes. My husband entered the water and the dolphins scattered away. I asked him to get back on the boat and the dolphins returned. I guess they could sense his uneasiness. The entire pod was extremely playful. The baby dolphins seemed to be very curious of my human form as the mother dolphins watched closely with approval. I continued playing with the pod when I noticed something rather peculiar. We were in around forty feet of water when all of the dolphins began to gather together to form a spiral coil. They were all facing upwards resembling a chain of DNA. I was in awe of such an incredible sight when I realized I was directly floating above. One by one each dolphin blasted me with thier sonar and darted away at phenominal speeds. This experience lasted well over two hours, but somehow I had imagined thirty minutes or less. This was the best mothers day gift I could ever recieve.”

– Linda Carol, Weston, FL

“Hi Bluewater Jon Schwartz here. I’m a big game kayak angler, and I travel all over the world to battle the ocean’s toghest predators — marlin, tuna, and shark- from kayaks. One story that may be of particular interest to you is that I caught and released 8 marlin from my kayak in 2 days this winter — with no help, other than getting a ride out to the fishing grounds. It was filmed by a professional videographer in HDV on a pro camera- I have almost three hours of tape, and TONS of “money shots” where the fish are doing their mad aerial displays within feet of my tiny 14 foot plastic kayak. I am also a elementary teacher and teach my children about marine science and conservation, taking them on trips to the ocean and fishing outings. This past winter I took a third grade student out with me on a kayak, launching at 3:00 am in the pitch black, and using live squid, we scored a 27 pound yellowtail! Other times I go fishing on my kayak before work and bring in my catches, like white seasbass, for a day of hands on science.”

– Bluewater Jon Schwartz, Carlsbad, CA

“Underwater science is usually rather dull. Hours spent collecting data. Data that’s not particularly interesting in and of itself. Data that becomes interesting only when conjoined with similar data from other sites and times.

While the media stars of underwater science like Sylvia Earle and Bob Ballard reach out from the pages of a glossy book or beckon from a tightly edited video production, crisp and seductive images that intersect at a precise and meaningful conclusion right there on the last page or in the last minute. Real life is not like that, at least not very often. It’s repetitious … hour after hour, cold, uncomfortable, usually strenuous, occasionally dangerous. But every once in a while, every once in a long while, there’s magic in the water. The universe clicks just right and something really special happens that makes up for all that’s come before, something really special … really, really special. This was one of those times.

It had been a hectic and eventful trip so far. I’d staged a close escape from one of those classic binds, having to be two places at once. I had to go out to sea on a research cruise, the ship was leaving the dock with the morning tide, but on the same day I was scheduled to deliver a paper at the annual American Academy of Underwater Sciences meeting.

My Director, Jim Griffin, insisted that both things get done, he’s like that, used to be in charge of the Thor-Agena Booster Program for North American Rockwell and firmly believed in that NASA motto of, “the difficult we do immediately, the impossible takes only slightly longer” Our ship was leaving Woods Hole and transiting the Cape Cod Canal on its way to the Gulf of Maine. If my talk was moved to the first slot in the morning and there were no hitches, I could be back in time to meet the ship at the north end of the canal just after sundown. I were late … Plan B goes into effect, a night-time, “casualty evacuation drill” with a USCG helo a good friend flew out of Otis. That’d be the cover for my Plan-B ride out.

On Friday I stowed the last of my gear on the ship and I caught an oh-dark-thirty flight out of Boston down to Florida. A quick cab ride and I was at the podium going over the slides that illustrated a paper I’d coauthored with Rich Pyle of the University of Hawaii on the use of mixed gas, open circuit scuba down to five hundred feet. Twenty minutes of talk, ten minutes of questions, I shook the moderator’s hand as I shoved my Certificate of Appreciation into my case and scooted out the back to a waiting cab that took me back to the airport. I ran for a plane back to Boston and on the plane I switched my tan Sunday-go-to-meeting suit for a pair of 501s, a black U. C. Berkeley sweatshirt and my topsiders.

My work study student, Dave Sipperly, was waiting for me curbside at Logan. I threw my leather flight bag and black Halliburton, the one covered with dive stickers, on the back seat, jumped in front and off we sped; south toward the Cape. Down Highway 3 to 6a, over the bridge at Sagamore and left onto Tupper Road, left again to Town Neck Road and one more left onto Coast Guard Road. There, at the north end of the canal was a small U.S. Coast Guard station. We pulled in past the whitewashed rocks.

I got out, retrieving my Zero-Halliburton from the rear seat., pulled a set of CANDIVE coveralls from the top of my flight bag, which Dave would drop at my office. We’d made good time, the ship was not due for a good half hour and Plan-B could go by the board.

I pulled my ICOM M5 out, slid a charged battery pack on the bottom and keyed it to 16. “Whiskey, Victor, Foxtrot, Quebec.” I repeated the call ship’s call sign three times and then identified myself, “This is WVFQ Port one, come in.” No response yet. I had some time to kill and the heavy humid air was cooling now as the sun dipped below the land west of the canal. I shivered slightly and went into the Coast Guard station.

I found the O.D. and explained that I was meeting a boat out of the Hole, and that it would heave-to outside the north end of the canal and send a Zodiac for me. The Coasties seemed happy to have something to break their routine; they offered up a mug of hot coffee and asked if I wanted to use their longer range base station to call the ship. The O.D. offered to save us time and confusion by running me out in their rescue boat.

I could see the ship in the canal. I pulled on the bright orange coveralls that Jim English, CANDIVE’s Operations Supervisor gave me when we’d worked with the Deep Rover submersible at the Caribbean Marine Research Center during Sylvia Earle’s record dive the year before (but that’s a story for another time). We went down to the dock, hopped into an overpowered hard bottom inflatable and sped out toward the oncoming ship, blue lights flashing and sirens screaming. We screamed past the ship, starboard to starboard, headed in opposite directions, came about in a tight turn to port and then pulled up along side the moving and much larger vessel. At about eight knots our boat slid smoothly over to the Jacob’s ladder hanging amidships on the starboard rail. When the Coastguardsman shouted, “Go!” I leaped from the port gunwale of the RIB, out across the black chasm and grabbed on to the Jacob’s ladder. The small craft veered off to starboard, throttled back and then came back up along side of me. I gripped a treadle with my left hand and leaned out. A Coastguardsmen handed my case up to me. I passed the case up over the rail to a fellow Explorers Club member who was making the cruse with us and clambered aboard. Not exactly the way I usually start a cruise, I was really having fun with “action movie” aspects of the situation.

Supper was still on in the mess. I had a meal and then we all got to work. The compressor van had to be hooked to ship’s power and run. The air had to analyzed and the bank brought up to pressure. Filling whips needed to set up at the waist and a 10,000 PSI Kevlar line run from the compressor up on the O1 deck down to the filling station. All our gear for the next day’s dive needed to be unpacked and readied. Contact with Offshore Medical Services had to made and communications with our contingency helicopter evacuation facility needed to be tested. With everything done, I rolled into my rack about 22:00 hrs and was out like a light.

Eight bells. I got up, showered, pulled on my coveralls and went up to get some chow. No one else from the science party was up yet. I had a chance to spend some time with the ship’s folks. I went over the general dive procedures with the Captain, who had stayed up beyond his usual midwatch so that we could talk. The Coxswain set up the diving Zodiac and we went over the boat and all of its gear. By now it was seven bells in the morning watch and the science party was drifting into the mess, pouring coffee and sitting down in the library and the lab.

We were due on station at Ammen Rock in the Gulf of Maine at the start of the afternoon watch. We were planning our first dive about two hours after later. The science party spent the morning setting up their computers and laboratory equipment. Each of the divers got his or her gear unpacked and stowed in the wet lab that had been turned over to dive locker space. As I hung up my black NATO Viking suit one of the University of New Hampshire grad students was heard to exclaim, “Oh! No! It’s Darth’s wader’s.”

Dive procedure’s pretty straight forward. The Zodiac is on the deck. You assemble your rig and put it in the boat. You put your weight belt in the boat. Then you go and get your suit on. By the time you’re dressed in, the ship’s crane has put the loaded Zodiac and the Coxswain in the water and the crew had rigged a Jacob’s ladder over the rail. The water is about nine feet down that ladder. The Zodiac is held against the side of the ship with a bow painter and a stern line and you clamber down the ladder into the boat. You put your gear on in the boat while it motors to the site. On the way the you run through pre-dive checks and once there, back roll off the inflatable’s gunwale into the water.

We needed to service some instruments. The bottom’s about 110 feet. It was a great day, visibility was more than 100 feet. There were immense numbers of herring in the area for their late summer spawning. Down we went through the loosely organized school to the tide gauges. It took about ten minutes to dump the data and reset the gauges; the herring cast enough shadow that we needed our dive lights to see what we were doing.

Our tasks done we were getting ready to leave, suddenly … in the blink of an eye … there was a snap from an eerie deep green to pitch black. The lights were out! Mounds of herring pressed closely in on us. I was completely blind. No gauges, no buddy, not even my light was visible. I raised my light and pointed it straight toward my mask. The beam burst into a million mirrored reflections off the herrings’ scales. I took a slow deep breath and felt myself lift off the bottom and begin to ascend. Carefully I maintained slight positive buoyancy with my lungs. I could not see my gauges. I could not judge my upward progress. My field of vision was filled with the scintillations of my light reflecting off the herring that had closed tightly in upon me.

As fast as the dark had arrived it was gone. My eyes were momentarily dazzled. I exhaled sharply and sank back into the darkness below. Another breath started me up slowly. This time, just as my head broke out of the tightly packed herring school, I exhaled gently and transformed my ascent to a hover. From my chin down and out as far out as I could see, there was a black mass of squirming fish so closely packed that there was little room even for water.

I turned to my left through about three-quarters of a rotation. I could see one of my three comrades coming up out of the herring mass, perhaps twenty feet away. She ascended about ten feet and pitched back to horizontal, leveling out and smoothly neutralizing her buoyancy. A circular motion of her light indicated she was fine, had seen me and inquired as to my status with that unique economy of the underwater “okay.” I brought my seemingly detached left hand up out of the darkness and responded in kind.

Suddenly, she pointed sharply to her left, her arm stiff and outstretched. I swiveled my head right, and there is one of the most incredible sights I’ve ever witnessed. Six Giant Bluefin Tuna move toward us, in formation, they pass between us. Each fish, the size of a dinner table that would seat eight, moving fast, yet without apparent effort. They glide past, each with a huge left eye that stutters for a tiny moment as it find me for a fraction of a second and then moves on to seek it’s normal prey. We watch them almost disappear, circle to the right, and move to the other side of the herring school. They come right back by us and go left to the other side of the seamount.

The black shinny mass beneath us starts to break up, the herring resuming more normal individual distances and expanding their school upward and outward. Once again enveloping me in darkness that slowly lightens to the deep green we saw at the start of our dive. I swam up to my teammate and joined her in a hover. We moved to the down line and ascended to our deep stop. Being out of the lee of the seamount now, the current is rather stiff, we tied off with our Jon lines, waited a minute and then ascended to our 20 foot stop.

Decompression complete we signaled the Zodiac, the Coxswain waived us off as he was already heading to pick up our other two comrades at an alternate surface float. Once we were in the Zodiac everyone was talking excitedly about the Tuna, there had been a big school of them working the herring and every one of us had been blessed with a good long view.”

– Phillip Stuart-Sharkey, Ocean View, HI

“As a fishing guide in the East Cape region of the Baja peninsula, billfish, specifically striped marlin, play an integral role in the big-game fishing experience. I have always been captivated by how unique billfish are as an apex predator, enough so to chase them all over the world. My clients have always express their gratitude for having such an opportunity as to experience a billfish in its environment and the great satisfaction of releasing a healthy fish back into that environment. The tide is slowly turning in the sportfishing industry to the adoption of catch and release for all billfish. More tournaments are promoting no-kill formats and new terminal tackle techniques are greatly reducing mortality rates. Hopefully the intentional taking of a billfish from a sportfishing boat will someday be a thing of the past. But with that said, billfish are facing a pretty tough future. As a guide, it’s not only my obligation to be an active conservationist but also to educate my clients on how special these fish are and how they can play a role in fighting the entities that threaten their existence. I want to thank Rick and his team for bringing as much exposure as possible to the pressures faced by billfish worldwide. I also want to thank organizations such as The Billfish Foundation and SeaWatch.org for fighting the good fight.”

– Mark Daugherty, East Cape Guides, San Francisco, CA

MISSION: SUPERFISH

Marine biologist and award-winning filmmaker Rick Rosenthal set out to capture on film the biggest, fastest, most dangerous gamefish in the sea — the ancient creatures known as billfish.

The largest of all billfish is the marlin. They top speeds of 60 miles an hour on migrations that can span 9,000 miles. The largest, always female, weigh in at over 1,000 pounds, and are known as “granders.” Ernest Hemingway immortalized the grander in The Old Man and the Sea, the story of an elderly fisherman locked in a life and death struggle with this apex predator. To Hemingway’s great disappointment, he himself never landed a grander, although his novella captures the impact of this huge and graceful creature.

Rosenthal’s pursuit of these exotic fish unfolds in NATURE’s Superfish. Two years in the making, Rosenthal’s documentary travels to the Pacific and Atlantic Oceans as well as the Caribbean Sea in pursuit of these giants of the deep. In one extraordinary scene, off Australia’s Cape York Peninsula, Rosenthal is shown swimming with a stunning giant female marlin and two courting males.

Throughout his journey, Rosenthal encounters commercial fisherman, anglers, and researchers, who are also out looking for billfish. The search has become increasingly difficult for everyone due to over-fishing of billfish and their prey, as well as the environmental degradation of the oceans, which has resulted in a dramatic decline in their populations. The trajectory of population decline in all large fish has been precipitously steep, estimated at 90 percent within the last half century.

In the 1950’s, sports fishermen — like those who flocked to Cabo Blanco, Peru in the heyday of “Marlin Boulevard” — were known for testing themselves against marlin with rods and reels. Today, some fisherman are defending billfish against commercial fishing fleets that, while going after the seafood we eat, kill these increasingly rare sport fish in their nets as so called accidental by-catch. In major part because of the absence of regulations that limit such by-catch, marlin and other billfish populations continue to decline. In the case of marlin, some anglers, frustrated with governmental inaction, have pressed for local bans on the sale of such fish, and have sought commitments from local restaurants not to serve marlin.

Rosenthal’s difficult quest to encounter a giant marlin in the wild, rewarded by his exceptional footage of this fabulous creature, not only offers a rare aesthetic and learning experience for viewers but may serve to awaken people to the need to preserve these remarkable billfish in their native habitats. Buy the DVD. This film premiered May 2008.

In Sharkland, you’ll learn why species that are normally found oceans apart converge in this one relatively small stretch of coastline, and you’ll be introduced to many of these unique animals, including the catsharks of the Agulhas Bank a 155-mile-wide stretch of shallow warm seas off the southeastern tip of the continent, Southern Africa’s richest fishing grounds. You’ll also explore nature’s most extreme sharks – the fastest, fiercest, smallest, and strongest – and discover the innovative adaptations that have made the Great White such an efficient killing machine.

To order a copy of Sharkland, please visit the Nature Shop.

Online content for Sharkland was originally posted May 2007.

Seafood lovers take note: there’s good news and bad news.

First, there’s the bad news for those who enjoy tuna on rye.

High concentrations of mercury, a neurotoxin that can damage developing brains in fetuses, are found in some kinds of popular fish such as albacore tuna. Swordfish and shark, king mackerel, marlin, orange roughy and tilefish also contain dangerous levels of mercury.

Women of reproductive age and young children are advised to avoid these types of fish and limit overall consumption of all fish to no more than 12 ounces per week, according to the Food and Drug Administration, as it takes months for the body to rid itself of mercury.

The danger from mercury is not just to developing brains. There is evidence to suggest an association between mercury exposure and heart disease, making it dangerous for everyone, but especially those who are already at risk.

The American Heart Association, however, recommends eating fatty fish at least twice a week because it is high in omega-3 fatty acids which are believed to help lower rates of heart disease, reduce hypertension, relieve some arthritis symptoms and prevent cancer. Fatty varieties that are low in mercury include herring, sardines, and wild salmon. Some popular fish that are also good choices include sole, tilapia, clams and oysters.

“It all depends on your diet — you can’t eat a lot of big, wild fish,” said Tim Fitzgerald, a marine scientist for Environmental Defense Fund, who provides health consumption information to Monterey Bay Aquarium’s Seafood Watch.

The problem with large, predatory species like marlin and swordfish is that they contain much higher levels of mercury than small fish, such as anchovies and sardines, because of the way mercury moves up the food chain. “Sharks, marlin, polar bears and people at the end of the food chain have the highest concentration of mercury,” Fitzgerald said.

It’s sometimes difficult for consumers to make seafood choices that are good for their health — and the environment. According to Tim Fitzgerald, “Billions of pounds of imported fish come into the United States annually, and less than one percent is tested for environmental toxins by the FDA.” Because marlin is not a popular dining choice in the U.S., many people are not aware of this. And while the FDA is the regulator body that creates consumer advisories about mercury for pregnant women, they actually do very little testing for this neurotoxin.

Another problem with the advisories is that they are not terribly specific and there’s a lot of room for interpretation, according to Fitzgerald. It’s also difficult for consumers to make the best seafood choices because sometimes what’s best for the environment is not always best for their health, and vice versa. For example, blue marlin and striped marlin from Hawaii are fairly resilient to fishing pressure and are listed as “good” alternatives for the environment on Seafood Watch. But, Seafood Watch also lists a health advisory for these fish, due to high levels of mercury. Monterey Bay’s other regional pocket guides provide further guidance for consumers and note that imported blue marlin and striped marlin should be “avoided.”

So, for U.S. consumers, the situation is “buyer beware — eat with caution,” but certainly not to give up on all fish. Consumers may just need some help from Monterey Bay’s Seafood Watch, which maintains a list of “which seafood to buy and why,” including a comprehensive seafood search, regional seafood guides — and printable pocket-sized guides for your wallet.

And, if you are a tech-savvy-seafood-lover, a “fish phone” may be more of what you’re looking for. Environmental Defense Fund’s Seafood Selector to-go allows mobile web users to look up their seafood guide on a blackberry or iPhone and download the information.

Ultimately, it’s ideal to exercise moderation and caution when eating seafood by taking into account both environmental and health concerns. Fortunately you don’t have to wonder whether the seafood menu at your favorite restaurant is environmentally friendly, the answers to your questions may just be a text-message away.