I recently found an old story I wrote while looking up some information about tagging and its benefits. When “Migratory Movements, Depth Preferences, and Thermal Biology of Atlantic Bluefin Tuna” was published in the 17 August 2001 issue of Science there were some great stories to tell. Stories that had to be kept as secrets until the paper was published in Science.
The data presented, and conclusions drawn from them by a team headed by Dr. Barbara Block from Stanford University (and including scientists, anglers and crew making up a who’s who of tuna angling , research and management) created shocks waves across the Atlantic.
National Public Radio, National Geographic News as well local, regional and national newspapers, had already discussed the ramifications of having tuna tagged off Hatteras, cross the Atlantic Ocean, and even enter the Mediterranean Sea in larger numbers than any previous estimates could imagine. This threw a monkey wrench into all management plans and conservation attempts, based on earlier theories, that eastern and western populations of bluefin tuna were separate and need to be managed separately.
Giant Atlantic Bluefin Tuna, each weighing over a quarter-ton — Photo by Guy Harvey
Two types of tags were used in the study, surgically applied internal “archival” tags and pop-up satellite archival tags (PSAT tags in the article’s jargon). Both showed that fish from the west cross over into the eastern Atlantic. These tags, plus captured fish with conventional spaghetti tags, raised the thorny issue of North American fishermen (commercial and recreational) accepting low catch quotas in order to allow the overfished tuna populations to recover, only to have the fish massacred in huge numbers in the Mediterranean and eastern Atlantic. (East of longitude 45 degrees West twenty metric tonnes of bluefin tuna were being caught for every tonne caught in the west!)
The Science paper is fascinating but takes some serious reading! It is not something you can glance at and retain. Some highlights, with some input from me from information gleaned during the tagging process, include:
There were 377 electronic tags in this study. Electronic tags were recovered from a few days to 3.6 years later, AND the TAG program continues to produce amazing results. Internal archival tags totaled 279 with 49 tuna being recaptured. This 18% return rate is extremely high and by itself suggests overfishing.
The 90% data acquisition rate from pop-up tags is a marvel of both technology and tuna survival rates. The return rate is higher since the fish does not have to be recaptured and the data is downloaded through the Argos satellite system. Although, the percentage of recovery is higher less information per tag can be retrieved, because of the high energy needed to send a radio signal, not just burn data onto a chip.
There were 7065 conventional spaghetti tags applied by Carolina tuna fishermen between the years 1994 and 2000. There were 292 recoveries (4.1%). This is a high rate in itself and valuable information was added, but it is obvious that trained scientific teams with top anglers and crews are more successful than the general public in properly applying tags. (One reason for non-return is probably mortality where a dead fish sinks or is eaten by sharks and the tag cannot be recovered.)
Some tags could record depth (through pressure) and location (by measuring the levels of light). Sunrise and sunset were the “most significant light events” and with an accurate electronic clock allow extremely precise east/west location and reasonable north/south estimates. It became apparent that Western tuna breed later in their lives than originally thought- another huge consideration in conservation and management.
Deep dives to over 500 fathoms (1000 meters) sometimes resulted in lowered internal body temperatures that experiments at the tuna lab showed to probably be the result of feeding on cold squid or fish living at those depths (Block fed captive yellowfins cold bait and measured cold internal temperatures.)
My question is “HOW DO THEY KNOW?” You can dive half a mile in most parts of the ocean and NOT find a meal!
In the field, the emotional highs and lows were enormous! The successful signal reception of the first pop-up tag started a major round of toasts and celebrations. Shortly after, on a rough and stormy night when the second pop-up tag failed to report in on its scheduled time, long faces abounded- until the weather eased and in calm water the tag sang like a bird to the overhead satellite. This alone allowed an adjustment, low tech but important, in additional buoyancy for subsequent tags.
Dr. Block was reduced to tears on the flying bridge one rough day when a large sea lifted the boat and one rudder hit and killed a tuna we were trying to tag. “I’m trying to save them- not kill them!” she sobbed.
The cooperation of anglers and crews, and their donations of time and money were an extremely important factor in the amazing success of this study and along with dozens of scientists and technicians all involved are to be highly congratulated! For more information get a copy of Science (17 August 2001). .
Recently, Paxson Offield was initiated into the IGFA Hall of Fame and a high light of his career and work in conservation was an ongoing program of PSAT tags in marlin. Currently, the internationally noted artist Dr. Guy Harvey is also a leader in not only tagging but other conservation initiatives.
We need people like Dr. Block, Dr. Harvey and Mr. Offield to help conserve our precious stocks of “Marine Megafauna”. AND we all need to do our part to help out.
See my next column in Marlin Magazine for a story of a Sportfishing CLUB gone BAD and becoming a detrimental group of swordfish killing amateur professionals.
Peter B Wright
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Stalking a bonefish school takes patience and persistence, but the result can be very gratifying in serene surroundings
Yeehaw! Line was pouring off the small spinning reel, and the rod tip was bucking as the fish took off toward deeper water. I had a bite and was tight to a reasonable sized bonefish. The fish took out a hundred yards of line in the blink of an eye and then turned right, so I waded quickly along in the shallow water near the beach to catch up with the fish, before it emptied the reel. In a matter of minutes, I had the bonefish doing circles around me, and I bent down and grabbed the short leader to hold the fish and remove the hook. I released a fine specimen of a Grand Cayman bonefish about five pounds.
Bonefish are found all around the tropics, even in the remote oceanic islands. Wherever they are found, they are a big draw for recreational anglers. For some islands, such as in the Bahamas, bonefish (and other shallow water game fish such as permit and tarpon) fishing excursions provide a major source of income for locals. It is likely that if diving was not such a developed eco-business here, there would be a lot more emphasis on the bonefish and tarpon fishing that these islands have to offer.
The bonefish has an elongated, torpedo shaped body with a slender head and a small, inferior mouth inserted under a pig-like snout. The single dorsal fin is placed in the middle of the body, and the large tail is deeply forked. The back is dark green, and sides are lined with shiny scales that reflect the color of the surrounding flats. The face looks as if it’s made from beaten stainless steel plates. This is a species I love to paint, but they are a big challenge, not only because of the detail and serial repetition of the scales, but also because the light playing on their back and the added detail in their shallow water habitat.
My good friend Billy Boyce holds up a big bonefish caught on one of the many sand flats surrounding the Bahamas
The bonefish is primarily a shallow water species, and is a very wary fish. They are so wary that many anglers claim that bonefish live in a constant state of alarm. Its habitat, for angling purposes, is the flats or intertidal areas adjacent to sand and coral islands or mainland beaches. Bonefish invade tidal flats on an incoming tide and feed on buried crustaceans, mollusks and small fish. They often travel in large schools and can be spotted from a distance because of the clouds of sand or silt they stir up. If the water is very shallow, their tails will stick out above the surface while they dig in the substrate with their pointed snouts which is called “tailing” and “mudding” in angling parlance. They will accompany stingrays and spotted eagle rays as they dig around the substrate looking for food items. Bar jacks also accompany the rays for the same reason. Bonefish may be accompanied by permit, small tarpon, small cobia and other species of jacks while they cross the sand flats.
Little is known about the life cycle of the bonefish. The egg hatches into a large leptocephalus which is transported by tides and currents into the open ocean. It metamorphoses from this 3-inch transparent eel-like larvae which gradually shrinks in size while it is transported by ocean currents away from the spawning area and hence to populate other locations. When this reverse growth is complete, a tiny bonefish is formed, and from then it wears chrome-plated scales and grows to twenty pounds. The average size varies according to the area in which they grow up, but 4 to 6 pounds is the average size.
A new tagging study on bonefish migration is testing a hypothesis that bonefish from Florida cross the Gulf Stream to the Bahamas, and then return. Tagged bonefish have been known to make coastal migrations and new evidence may soon emerge about deep water transits, which by extrapolation, would then suggest that bonefish could move between the three Cayman Islands.
Got some time on your hands and a good weather day? Then grab the fly rod, or the spinning rod, and some conch, cockles or shrimp for bait and head out to Frank Sound, South Sound or Barkers, and spend some time getting close to nature. Stalking a bonefish school takes patience and persistence but the result can be very gratifying in serene surroundings. Tight lines!
— Guy Harvey
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I seriously question the speeds often given for any fish, especially when Wikipedia and some reputable some encyclopedias claim that sailfish are supposed to be the fastest fish and can hit 60 miles per hour.
I once went to several references and online sites looking for Orca speeds. I found a range of speeds from 25 to 35 miles per hour (from here on shortened to mph) on the publications and web sites. None were anywhere near as fast as some the speeds some fish can supposedly attain.
Since Orcas can run down, catch, and eat, blue fin tuna, I question all the old, unsubstantiated fish speeds. I believe the speed of most fish is highly exaggerated by anglers, especially fishing writers. How excited can a reader get when reading about a bonefish tearing line off a reel at 15 mph, which is slower than many humans can run? In my youth, I could run down a beach in shallow water fast enough to avoid losing line to even a big bone.
Billfish, like this jumping Blue Marlin, are considered to be some of the fastest swimming fish in the sea. Photo by Richard Gibson
As a long time big game fishing guide, part time and ex Biological Oceanographer with decades of personal experience, ( called anecdotal evidence by scientists) I am positive no marine fish can exceed about 25 mph. I often chase large marine fish (tuna and marlin) with a boat and quickly catch them at 20 mph.
In addition, if a fish jumped straight up at 60 mph (88 ft/sec), simple math shows that after one sec the force of gravity (32ft/sec/sec) would have slowed the fish to 38 mph (88ft/sec -32ft/sec = 56ft sec which is 38 mph) The height of the fish at the end of that one second would be 72 ft and it would still going up at 38 mph. Height equals AVERAGE velocity times one second. Average V would be 88 + 56 divided by 2 giving a height of 72 feet.
Last but not least, there is the study AFTCO did decades ago which showed how much frictional drag there was on given lengths of line being pulled through the water. If any fish could go even 30 mph, they would break off before any crew could clear the lines and merely backing up would not make enough difference to avoid breaking the line.
Big fish eat little fish and the biggest predatory fish are the fastest. I doubt very much any fish can go 30 mph — it is too easy for Orcas to catch them for fish to obtain that kind of speed and no one says Orcas can hit 60!
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Historic Big Game Club Introduces Lionfish Nuggets
ALICE TOWN, BIMINI – OCTOBER 17, 2011 – With more than 400 servings of a new menu item last month, Bimini Big Game Club‘s General Manager Michael Weber and Chef Alvarez Bastian have found a recipe to help the environment and sate the most discriminating palate at the same time.
The Bimini Big Game Club’s Panko Breaded Lionfish Nuggets are the talk of the island, a gourmand’s answer to a tasty snack and an eco-solution for helping to rid nearby reefs of an aggressive and non-native predator.
“Our lionfish nuggets have become a huge seller. Though we don’t serve endangered species such as grouper – and we were the first Bahamas resort to feature a shark free marina – we have absolutely no problem turning lionfish into a menu item,” said Weber.
The colorful and charismatic lionfish, a member of the venomous scorpionfish family, are native to the Indian Ocean and South Pacific Ocean. First observed in Fort Lauderdale in 1985, they appeared in noticeable numbers in the Caribbean Ocean and Florida waters around 2000 and have continued to aggressively breed. Scientists are quite concerned that lionfish may be completely reinventing the western north Atlantic coral reef ecosystem.
“There are enormous concerns that lionfish will completely change and possibly destroy Atlantic coral reefs by overrunning them and shrinking their native biodiversity, and that the ongoing damage is severe and possibly irreparable. So far, there is no known quick-fix, and the problem is escalating exponentially.”
Weber is quick to admit that turning lionfish into finger food is far from a solution, but with proper cleaning, the lionfish meat is excellent in taste and texture, and any that make it to the table means “they are no longer a threat on the reefs.”
Recipe for Panko Breaded Lionfish Nuggets a la Bimini Big Game Club
(Please carefully adhere to cleaning recommendations before preparing)
Lionfish Nuggets:
4 oz of Lionfish
Flour
1 cup liquid egg
Panko breadcrumb
Salt & Pepper
Cajun seasoning
In 3 separate bowls place your liquid egg, flour and breadcrumb. Cut Lionfish into small bite sized pieces and season with salt & Pepper & Cajun seasoning. Dip pieces into flour, shake off excess flour, and then dip into liquid egg and then into Panko breading. Once covered in the breading they are ready to take a long hot bath in some hot oil at 325 degrees until crispy golden brown.
Homemade Cilantro & Key Lime Tarter Sauce:
Mayonnaise 1 cup
1 Gherkin’s or small Pickle
2 TBS Key Lime juice
6 leaves of chopped Cilantro
2 TBS of chopped Capers
Make sure all above ingredients are FINELY chopped. Mix the above ingredients in a mixing bowl and fold ingredients together and add salt & pepper to taste. Refrigerate until time of service to remain fresh. Enjoy!
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Giant Bluefin tuna are the largest tuna species in the oceans and can attain weights over 1500lbs. Photo by Bill Boyce
The cold clear green water got my heart started as I turned to face the oncoming fish. I saw the first one rise out of the green abyss, gliding, silent and purposeful, eyes wide, mouth slightly agape, the dorsal fin suddenly raised, pelvics lowered and the gills flared as the fish inhaled a slowing sinking herring. It turned sharply and the afternoon sun caught its bronze flanks and the water around the fish was momentarily lit in a golden glow. The fins and tail cut the surface and the bubble stream followed the fish down into the green depths. Then another one rose up and another and then several came in a rush to suck down the drifting herring…..one came so close I could see the scale detail on its cheek and it popped its gills the size of trash can lid. Then a blur of bright yellow finlets as the huge fish passes. The average size of these giant bluefin tuna is 800 pounds. Giants… is the correct terminology. These fish are up to 12 feet long with a 7 foot girth and several that swept by me were in the 1,200 pound range. I panned my video camera on them as they swam past me gobbling up the chum that kept them close to the boat.
In the late summer and fall these remnants of a once larger population of bluefin tuna take advantage of large schools of herring spawning in the Gulf of St. Lawrence and around Nova Scotia, Canada. They put on weight prior to undertaking lengthy migrations south to the Gulf of Mexico or swim across the Atlantic to the Mediterranean.
I was on board the “Fin Seeker”, a 50 foot lobster boat from Wedgeport, owned by Erik Jaquard and crewed by sons Joel and Camil who had a permit to take 5,000 pounds of bluefin this season. Erik was very selective about what tunas were taken (only five in six days of fishing) and the rest were all tagged and released for science. Those fish that were harvested were meticulously cleaned and iced down before being shipped by air to waiting markets in Japan.
There are two research efforts currently under way in Nova Scotia, one being conducted by Dr. Barbara Block of the Tuna Research and Conservation Centre, based at the Stanford University’s Hopkins Marine Station, please visit: http://tunaresearch.org/. The GHOF gives this research organization a small grant to assist with this effort which is based at Port Hood in the northern district of Cape Breton.
The other research effort is being conducted by Dr. Molly Lutcavage of the Large Pelagics Research Centre based at the Natural Resources Conservation Dept , University of Massachusetts Amherst, please visit: http://tunalab.org/. Dr. Lutcavage’s team were based in Wedgeport in the southwest. The plan was to visit both operations and conduct interviews with respective scientists and crew. Both teams have spent the last decade in the field tagging and tracking the migrations of the bluefin tuna along the eastern seaboard of North America and across the Atlantic to Europe.
Their results have indicated main feeding areas, spawning areas, trans-Atlantic migrations and have assisted in the sometimes controversial management of this species by ICCAT, the international organization that allocates quotas and attempts to regulate commercial fishing for this valuable nomad of the ocean.
This is not my first brush with giants. In January 2003, I did a shoot with Barbara Block off Cape Lookout, North Carolina while she was tagging medium sized and giant bluefin tuna, for my TV series “Portraits from the Deep”. “Giants” are individual tuna that are over 315 pounds and this species grows to at least 1,500 pounds. The previous year I had visited the tuna traps or “almadraba” in Tarifa and in Barbate on the southern coast of Spain. Here I dived with the captive tunas caught in land based traps and witnessed the harvest of 300 giants in a 2000 year old ritual that began with the Phoenecians and then the Romans.
Guy Harvey is working on a Bluefin Tuna Documentary
Long before the species became desirable food, the bluefin tuna was fished by recreational anglers out of Wedgeport, Nova Scotia from 1935 until 1975 in a famous tournament called the Sharp Cup which attracted international teams from many countries. Of these large, powerful animals Charles F. Holder said “Weight for weight, they have double the fighting power of a tarpon. They are living meteors that strike like whirlwind and play like a storm”. Some say the recreational fishery, catch and release only, should be revived in Nova Scotia.
In the early years this species was fished sparingly by harpoon, some were caught on line for canning as they were more of a “nuisance fish” damaging gear set for herring and mackerel. In the mid 1970s demand in Japan for the fresh tuna grew exponentially and so fishing effort for bluefin tuna was greatly increased. Industrial scale long lining and purse seining were added to the traps and harpoon fishery so the populations of bluefin tuna declined to the present day levels where some authorities consider the species close to commercial extinction. However, the researchers are of the opinion that if the quota system is properly regulated (as it certainly appears to be in Canada) then this fishery has the potential to be sustainable in spite of the huge worldwide demand for bluefin tuna sushi.
Along with my documentary producer and camera man, George Schellenger, I spent three days with the crew of the “Fin Seeker” as willing anglers using ultra heavy tackle caught, tagged and released some two dozen giants. Pop-up archival tags were deployed on many fish following capture. The hook was removed using a de-hooking device and the tunas swam free. The PATs record the migration of the tunas as well as depth and temperature data along their routes. A special physiological adaptation called a counter current heat exchanger allows metabolic heat to be kept in the body and not lost through the gills thus maintaining the body temperature well above ambient temperatures, allowing faster swimming speeds in areas rich in prey species. Being “warm blooded” these giant tuna, often called “super fish”, can penetrate the cold northern latitudes and dive to great depths in search of fish and squid.
The winter is coming soon and bad weather arrived so I was unable to visit the Tag–a-Giant research team in Cape Breton. They will be back next year and I will complete the documentary shoot with them at that time. Meanwhile, I will be completing the story of the life cycle of the bluefin tuna including interviews with other research efforts to study aspects of the early life history of this long lived super fish.
What a thrill to spend an hour in the water with these magnificent creatures and to capture their brilliant colours and movement for my next work. These are big fish and I will need to prepare a big canvas. The adventure continues….
It is our collective responsibility to conserve the marine environment and maintain the biodiversity of the planet.
—Guy Harvey
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Masses of Dead Red Snapper shows the result of rushing to remove offshore oil rigs by using dynamite
Last week on this blog we reprinted an excellent report from Doug Olander, editor of Sport Fishing Magazine, entitled “Stop the Plan to Destroy Our Gulf’s Living Coral Reefs” and the attached photo is a follow up to that blog.
Sportfishermen appreciate the habitat value provided by offshore oil rigs. We think it is important to understand and evaluate the importance of this habitat prior to removing the rig once the oil beneath it has been extracted. Some in the extreme environmental community are so blinded by their dislike for the oil industry that they push to have this important habitat removed without consideration of its potential future habitat value as an artificial reef site. They call it junk on the bottom of the ocean, while the fish and other ocean life call it home.
Since 1995, AFTCO, starting with our former Chairman Milt Shedd, has been working in California to help create a Rig-To-Reefs program. The goal of this program was to evaluate habitat value of an offshore oil rig before it was removed. If it was determined to be a net positive to the marine resource, the underwater portion of that rig would left in place as a life producing artificial reef. The photo shows the obvious damage that canbe caused by removal of an offshore oil rig. But what about the unseen loss? What about the vast quantities of marine life and habitat that is destroyed sight unseen? Converting off shore rigs to artificial reefs can be a valuable tool in our collective efforts to look after the ocean resource.
— Bill
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In an editorial a few years ago, I asked this question: Would anyone mind if the federal government ordered hundreds of coral reefs around the Florida Keys to be dynamited into rubble and hauled away?
One hopes the rhetorical nature of that is obvious. Hell, yes! The uproar would be huge, particularly among environmental groups such as the Natural Resources Defense Council.
So I have to wonder why such environmental groups haven’t spoken out against destroying hundreds of living coral reefs in the northern Gulf of Mexico. In fact, at least one — the NRDC — is on record actively opposing any effort to stop such destruction. These groups are aware of the plan, but I suspect most of the public is not or there would be more pushback.
While any government directive to destroy reefs may sound crazy, here’s how it’s going down.
For years, the feds have obligated oil companies to eventually yank out all non-producing oil rigs in the Gulf. That has been happening, but slowly.
Late last year, in what the Coastal Conservation Association calls a knee-jerk reaction to last summer’s oil disaster, the U.S. Department of the Interior announced a directive that all such rigs be pulled out within five years.
That would mean at this point, about 650 offshore rigs would be destroyed. That’s 650 individual, massive, living, vibrant coral-reef ecosystems — obliterated. (And keep in mind, these are huge vertical reefs offering structure and coral where otherwise there would be only barren, smooth bottom.)
But now there may be hope — in the form of federal legislation just introduced by Louisiana Sen. David Vitter called the Rigs to Reefs Habitat Protection Act of 2011. “I appreciate the Coastal Conservation Association bringing this issue to my attention,” he says. “More than ever, we need to create habitat for marine life in the Gulf, not dispose of it. These idle rigs are serving a valuable purpose supporting our fisheries.”
Indeed, Dr. Bob Shipp, chair of the Gulf of Mexico Fisheries Management Council has theorized publicly that one of the main reasons the Gulf is truly swarming with red snapper is the existence of so much habitat where decades ago there was so little.
The Rigs to Reefs Habitat Protection Act would not allow platforms to be removed until assessments are completed to determine whether a platform supports coral populations or other protected species, and to identify any species that have recreational or commercial value. If it is determined that a structure supports substantial reef ecosystems, its decommissioning would be halted until it can be determined that removing it would not harm the reef ecosystem.
A breath of sanity, you say? A big 10-4 to that: From this angler/conservationist, a huge thank-you to both Vitter and CCA.
BUT — the fat lady is far from singing on this one. Legislation proposed and legislation enacted may be poles apart.
You can help save the Gulf’s living reefs — and I hope you will by taking just a moment to click here to go to the CCA web site and send a message to your legislators supporting Vitter’s bill.
Don’t let public apathy or astoundingly misguided “environmentalists” destroy the Gulf’s vast, thriving reef system. As sport fishermen, let’s show, yet again, who the true environmentalists are. Put another way, ask yourself: “Is saving a living coral reef and its communities of marine fish worth one minute of my time?” Do it now — and pass it on. Together, we can stop the destruction of the Gulf’s reefs.
— Doug Olander
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I was four hundred miles west of Grand Cayman, on the continental shelf just to the east of Isla Mujeres, Mexico looking for bait balls of sardines with sailfish feeding on them, while shooting an episode of my TV show “Portraits from the Deep”. Frigates birds circling over the bait will normally announce the presence of sailfish, but just a hundred yards ahead of the boat, I spotted a frothy commotion. Big splashes and the tips of large fins broke the surface sending up volumes of white water. It looked like a sea monster was about to erupt from the surface as we quickly motored on over to see what was happening.
It seemed that two large manta rays were chasing an even bigger manta ray. I jumped in the water, camera in hand and finned hard toward the group of animals that were doing circles in front of me, tearing up the surface in their frantic efforts to keep up the chase. The large female turned directly at me, and with great beats of her twenty foot wings she came head on and swept just a foot beneath me, as I sucked in my stomach to make room for her passing. The two males in ardent pursuit also went by below me. I swiveled to continue the sequence and then she angled her left wing down and dived like a fighter jet, and went out of sight, with the two suitors in hot pursuit. It was two fourteen foot males trying to entice a twenty foot female to mate, but she was having nothing to do with them!
In the Atlantic Ocean manta rays are found in areas with a high concentration of plankton, such as in the western Caribbean off the coast of Mexico and Belize, and in the southern Caribbean off Venezuela, in the same areas frequented by whale sharks
Manta rays are different from all other pelagic rays in that they have two large fleshy lobes, called cephalic limbs on their head, that look like horns, hence the other name given to them , “Devil Ray”. These are actually paddle like in shape and while the ray is feeding with its large terminal mouth wide open they help guide food into the open mouth while swimming forward, often at great speed. In Mexico and Coats Rica, I have seen them attack schools of balled up sardines with rapid lunges and great determination.
When swimming along these horns are rolled up neatly for streamlining. Their coloration is generally dark brown or black on the upper surface, white on the lower surface, with a number of irregular black blotches. Sometimes there is more black than white on the underside. There may be areas of white streaks on the upper side, and sometimes the tips of their magnificent wings have white. Each animal is distinct and different. The smaller related species, the Devil Ray has a brown or even tan upper surface. Their tails are thin but generally quite long
Guy's first hand observation of Manta Ray's has inspired the artwork depicted on this t-shirt from his sportswear collection
A set of gill rakers on their gill bars catches all the microscopic organisms in the same way for other large plankton feeders such as whale sharks, and basking sharks.
Little is known about growth rates and their life history. Opportunities for study have come about recently because of their ability to survive in captivity in large aquaria such as at the Georgia Aquarium, and at Atlantis in Nassau, Bahamas. Mantas are reported up to twenty five feet across, weighing three tons. They probably reach maturity at a large size, and are long lived animals as are all the other large cartilaginous fishes, the sharks and rays. They give birth to fully formed miniatures of themselves that weigh up to thirty pounds.
Adult mantas have few natural predators, such as large sharks and orcas, but most are killed by humans, some are caught in gill nets or harpooned for food as seen on the Pacific coast of Mexico and the Orient, and many are taken as by-catch on long lines set for tunas and swordfish. Oh yes, a manta will eat a bait on a line. I caught and released a couple in Costa Rica while live baiting for black marlin. I have cut off and set free many mantas hooked on long lines in the eastern Pacific. Many mantas are caught in purse seines set on flotsam in the yellowfin tuna and big-eye tuna fishery in the tropical eastern Pacific.
As with most large oceanic animals manta rays are overexploited wherever they occur. However their popularity in certain islands frequented by divers is their saving grace in such accessible locations. Given the choice of seeing a huge manta glide by on twenty foot wings or see it cut up in pieces on an Asian dock, I think most people would choose the former. It is our collective responsibility to conserve the marine environment and protect the biodiversity of our planet.
Good fishing, safe diving.
—Guy Harvey
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featured blog posts and to see the full line of Guy Harvey Sportswear, please
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The sale of Guy Harvey Sportswear supports the marine resource in many different ways with its sale of each Guy Harvey product, a contribution is made to the GHOF
During the spring sampling season, three ongoing projects of the Florida Program for Shark Research at UF’s Florida Museum of Natural History, one in collaboration with researchers from Florida State University (FSU), focused on the distribution and movements of adult and subadult sawfishes in the southern portion of its Florida range.
We produced a survey of the waters surrounding U.S. Navy properties in the Key West region in order to determine the current status of sawfishes in those areas for the U.S. Navy/U.S. Army Corps of Engineers. Because of obvious security constraints, we were the first fish biologists to sample in these waters in decades.
Concurrently, in conjunction with Dean Grubbs and fellow FSU scientists and the John Carlson of the National Marine Fisheries Service, we sampled the middle and lower Keys and Tortugas region and Florida Bay, catching and satellite tagging eleven sawfishes. Satellite tags give long time and distance of movement information and we hope our tagging will help us better understand seasonal horizontal (up and down the coast) and vertical (depth) movements of the critters.
We also caught and multiple tagged two large adults in Florida Bay, the tags being traditional “spaghetti,” satellite, and active acoustic models. The last allowed us to manually track the minute to minute movements using a receiver held under the boat. Our first saw was “lost” within the first hour or so as it gave us the slip by scooting over a shallow bank, then boogying before we could detect its signal. Having learned our lesson, on our second capture we got in 38 hours of tracking over three days, including day-night comparisons. The sawfish moved about in deeper channels by day, then moved onto shallow, seagrass beds by night. It chose the same shallow grassy area on successive nights, demonstrating some short-term site fidelity. Next spring we plan to initiate placement of underwater listening stations on the bottom and tag the sawfishes with passive acoustic tags. These tags will leave a unique “bleep” on any receiver as the sawfish swims near, allowing us to track localized movements over longer periods and larger areas. We also will continue to satellite tag these and other sawfishes.
While sampling for sawfishes we also caught many sharks and rays. All of these animals also were measured, sexed, sampled (tissue for DNA) and tagged as part of ongoing studies of their biology and movement patterns. We also continued our work in Indian River Lagoon (IRL), where we began tagging young bull sharks with spaghetti and passive acoustic tags in a “new” region for us, the St. Lucie River estuary. This work is being done with our colleague, David Snyder, of Continental Shelf Associates. We also continue to download data from our underwater array of receivers in Mosquito Lagoon, Banana River and the northern IRL, where tagged bull sharks and rays still roam.
During this time period we put 5000 miles in land travel on the Guy Harvey adorned Hell’s Bay and God only knows how many sea miles on our faithful vessel!
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.
