4. The Bluefin Tuna
Price data for tuna is sparse, but approaching the market from a conservative perspective and viewing other indicators for the broader seafood market should be sufficient to make the argument about tuna’s future pricing.
At first, it is easy to dismiss the idea of seafood as an investment. It is difficult for investors to access, data is hard to come by, it is illiquid, and overall it is very strange. But it is for these very reasons that seafood has substantial potential. Figure 4.1 is an index of a basket of commodities from December 1995 to October 2010. Note that the index includes global seafood prices (salmon and shrimp) in its calculation. Figure 4.2 tracks the returns of fish products (salmon and fishmeal, dried ground fish used to feed livestock and farmed fish) against crude oil, wheat, and copper over the same time period.
Figure 4.1. Basket of commodities from December 1995 to October 2010
Source: http://www.indexmundi.com
Figure 4.2. Salmon and fishmeal prices compared to other commodities
Source: http://www.indexmundi.com
The focus of this chapter is not to discuss the generalities of seafood but rather the specifics of tuna—namely, bluefin, a population that is on the brink of extinction. According to the United Nations Food and Agriculture Organization, 7 of the 23 commercially fished tuna stocks are overfished or depleted, and an additional 9 stocks are threatened.
There are two main geographical areas that need to be understood when understanding the Tuna business; Australia and Japan. Australia, namely places such as Port Lincoln, are at the epicenter of both tuna fishing and farming. Japan, another location where considerable amounts of tuna are caught, also serves as the primary exchange for seafood and giant Tuna. Both Port Lincoln and the Tsukiji market in Tokyo are touched upon in this section.
Australia
I was in Australia observing the lifeblood industry of Port Lincoln: the feeding of fish that will be transformed into the town’s major export—southern bluefin tuna for Japan.
After an hour, we arrived at the first pen, some 5 miles offshore, east of Boston Island. The five pens clustered together are a part of the 14 maintained by aquaculture company Stehr Group. They are round, floating corrals, 120 feet across, consisting of nets suspended from a ring of stanchions mounted on a circle of floats. Some 50 feet deep, the net corrals each hold between 1,000 and 2,000 half-grown southern bluefin tuna caught in purse seines in the Great Australian Bight to the west. They were transferred at sea to towing cages and, after a 1-knot tow that can take as long as three weeks, were transferred again to these floating pens. These tuna are a precious commodity—which is exactly the right term—and they are pampered and coddled to an extent that would embarrass a purebred Pekinese. Every day of the year, the bait boats make the 5-mile journey to the pens around 6 a.m. and then return to the Port Lincoln marina to pick up another consignment of baitfish to feed the penned tuna. At 2 in the afternoon, they do it again. Stehr Group feeds 60 tons of pilchards a day to their tuna; over the season that adds up to 5,500 tons.
Frozen blocks of foot-long pilchards, imported from California and eastern Australia, Morocco, and even Europe are fed to these piscine gourmands. When our boat has been made fast alongside the pen, the feeding begins. Just as your pet guppies know when you are about to sprinkle fish food into their tank, the tuna know that the arrival of the bait boat signals a feed. They pick up speed in their endless counterclockwise circling. Sometimes they break the surface with their pointed dorsal and tail fins. Sometimes they roll on their sides to flash a gleam of silver, yellow, and blue and a curiously intelligent glance at the bait boat. The feeding begins as a man tosses one shovelful after another of pilchards into the pen, causing the water to boil with tuna rushing to get their share. So that they do not land in a clump, the shoveler, with his back to the pen, tosses the fish over his shoulder in a graceful arc. Looking down on the feeding frenzy, I notice the bright yellow, horizontal keels at the base of the tail; these yellow markers are the most prominent features of the tuna zooming by underwater. (And, says Jessica Farley of the Commonwealth Scientific and Industrial Research Organization (CSIRO), this may be one of the characteristics that differentiate the southern bluefin from its northern relatives.)
Catching fish to feed fish is an ecologically unsound concept, but tuna are carnivores (more accurately, piscivores), and they would not eat food made from grain. Research is now being conducted to develop a grain + fish products + vitamins pellet that would be the equivalent of the “fish food” sprinkled into your home aquarium. But tuna need fat in their diet to produce the fatty meat that the Japanese prize so highly, and although grain might be used to fatten beef cattle, it doesn’t work that well for tuna. (Curiously, the Kobe beef so highly prized by Japanese gourmets looks very much like the best bluefin tuna sashimi (raw fish): rich red in color, marbled with fat to give it the desirable texture and flavor.) So for the moment, thousands of tons of small fish are being caught and exported to Australia to feed the tuna that will end up in the Japanese fish markets and, ultimately, in high-end restaurants, where a piece of uncooked fish can sell for hundreds of dollars.
Southern bluefin tuna, known technically as Thunnus maccoyii and commonly as SBT, are born in Indonesian waters. For the next eight years, they leisurely work their way around the west coast of Australia, crossing the Great Australian Bight en route to the east coast. There they disperse—some swimming to New Zealand, and others to South Africa. Some of the seven- or eight-year-old fish completely circumnavigate the Australian continent and return to the Indonesian waters where they were hatched to spawn and begin the cycle anew. But many will not make it that far. They will pass unscathed through Western Australian waters and the Great Australian Bight, but then they will find that their migration route has brought them into the perilous seas off South Australia, where boatloads of fishermen with nets are dedicated to keeping them from completing their instinct-inspired journey. (No tuna fishing occurs in Western Australia. The fish are not big enough, so the quotas were sold years ago to South Australian fishers.)
The first Australian tuna fishermen caught their quarry in an old-fashioned, labor-intensive way: They hooked them on a line and jerked them out of the water one at a time. For bigger fish—these fish can weigh over 400 pounds—two men would use a pole each, attached to a single hook. The hooks were barbless, so as the fish were yanked out of the water, the hook pulled out and the fish flopped onto the deck. (Later, a thick foam-rubber “blanket” cushioned the fish’s fall so that the valuable tuna would not be damaged.) “Poling” was replaced in the early 1960s by purse seining. A huge net was deployed around a school of tuna and “pursed” to close it around the fish, which were then hauled up on deck. When the Japanese developed a taste for sashimi, Australian fishermen, particularly those in Port Lincoln, labored long and hard to satisfy the Japanese lust for tuna. South Australian fishermen brought the fish to the Port Lincoln docks, where Japanese freezer ships waited with their eager holds agape, ready to carry the frozen carcasses to the Tokyo fish markets. Government scientists, worried that intensified fishing posed a threat to the southern bluefin tuna stocks, imposed such strict quotas on the fishermen that they believed they were being drummed out of business. Tuna farmers to the rescue.
Tuna farming (sometimes called tuna ranching) utilizes the same “feedlot” technology used for cattle, except that it takes place at sea, mostly underwater. Young animals are herded into special enclosures, where they are fed until they reach the desired size and weight, at which point they are slaughtered for human consumption. Spotter pilots locate schools of tuna and radio their location to the waiting “chum boats.” Fishermen on these boats throw baitfish into the school, causing the tuna to become excited and follow the boat. The chum boat pulls close to the purse seiner (Australians say “purse seiner” as one word: “per-say-ner”). A net is shot around the school of fish and the chum boat. The spotter pilot overhead directs the boat out of the net just before it closes, leaving nothing but fish behind. The net is pursed around the school, perhaps thousands strong. When it is closed and the tuna are trapped, it is drawn alongside the towboat, to which is attached a large net “cage,” open at the surface (see Figure 4.3). The cage is used like floating corral to tow the fish to the pens off Port Lincoln. Many net hauls are transferred to a single towing cage, which can hold as much as 150 tons of fish. At the pens, the towing cage is brought alongside. Divers open adjacent panels in the towing cage and the pen, driving the fish into the pen, where they will remain for the rest of their lives. About 150 pens are clustered off Port Lincoln in Boston Bay and off Rabbit Island, each owned by a particular tuna company, which will feed the fish twice daily, every day of the year, until the time comes for them to be killed. Each pen contains anywhere from 20 to 50 tons of fish.
Figure 4.3. Purse seine fishing
Because you cannot easily count fish underwater—much of the school is too deep to be seen even by the spotter pilot—only rough estimates of the school’s size can be made. However, experienced spotters can calculate the size of the fish in a given school with remarkable accuracy, so they can advise the catchers as to whether the school is worth pursuing. Kiwi White, a spotter pilot since the 1960s, told me that he can differentiate 17-kilo fish from 19-kilo fish from the air. If the fish are small—say, less than 20 kilos—you can catch more fish in a single haul, but you will have to feed them longer to get them up to market size. Catching larger fish means fewer fish in the cage, but a shorter time to feed them, which means less of the expensive baitfish are required to fatten them up.
Depending on various factors—market price, Aussie dollar versus Japanese yen, abundance of fish, size when caught—the tuna are kept in these fattening pens for several months, or even a year. When the tuna are considered big enough to be slaughtered, a platform is lowered into the pen, and divers in wet suits get ready to kill the fish. One diver shoves a fish up onto the ramp, and another grabs it by the gills and hauls it partially out of the water. While a metal spike is driven into its brain, another metal rod is shoved down its backbone so that the dying fish will not tense up and thus spoil the tender meat. This “humane” method is employed in Australia and other locations where the fish are small enough (less than 100 pounds) to manhandle. In Mediterranean ranches (such as those in Spain) where the tuna are fattened to 250 pounds (120 kg) or more, a man cannot restrain a struggling fish that is much stronger and heavier than he is. So the tuna are herded into a corner of the pen and are shot by men standing on a platform above the pen. “Shooting fish in a barrel” indeed. In Maltese fish farming, the living fish is lassoed around the tail, hauled up out of the water, and shot in the brain, or its throat cut so that it bleeds out.
There are many ways for a southern bluefin tuna to make the long—but often remarkably fast—trip from Port Lincoln to Tokyo. Sometimes the dead fish are taken to factories in Port Lincoln, where they are gutted, iced down—but not frozen—and packed into plastic-lined, coffin-shaped boxes for shipment by air or sea to Japan. Sometimes the fish are transferred directly to waiting Japanese reefers, where they will be gutted and iced down for a sea voyage to Japan. Other times they are loaded into huge bins (again iced but not frozen), trucked from Lincoln to Adelaide, and placed on a plane to Sydney, there to be transferred to a plane to Tokyo. Some of these tuna take only 30 hours to get from Port Lincoln to Tokyo, admirably fulfilling the Japanese requirement for fresh fish. Because they have never been frozen, these 30-hour fish are probably the most desirable at the Tsukiji tuna auctions. But even frozen fish from Port Lincoln’s tuna farms, pampered and virtually hand-fed, also demand particularly high prices. So far, the record price for a single fish at the Tsukiji tuna actions is $173,600.
In his 1996 book, Tuna and the Japanese, Takeaki Hori claims that the idea for tuna ranching originated with a Japanese tuna auctioneer named Hideo Hirahara. He went to Australia to find somebody to catch the tuna and put them in some sort of “fish tank,” where they would be fattened for three to six months, killed, frozen, and shipped to Japan. He found tuna fisherman Dinko Lukin. Even though he was not the first to “farm” tuna, the Yugoslav-born Lukin is surely one of the pioneers of the enterprise.1 At first, the tuna were caught with baited hooks and transferred to floating pens, but this proved to be too harmful to the fish. So with Hirahara, Lukin claims to have devised the scheme whereby they would purse-seine juvenile tuna in the Great Australian Bight and tow them in underwater cages to the waters off Port Lincoln. Whether it was Hirahara, Lukin, Joe Puglisi, or somebody else, whoever thought of tuna ranching rescued a faltering fishery and transformed it into a multimillion-dollar business. Tuna farming launched the little fishing village of Port Lincoln into the stratosphere of economic prosperity.
In 1991, only a couple of years after the Australians set up the first “experimental grow-out project,” Takahiko Hamano, a tuna-farming expert, and Yoshio Koga, a fisheries biologist, were in South Australia. They were part of a joint $1 million project involving the Japanese Overseas Fishery Cooperation Foundation (OFCF), the Australian government, and the Tuna Boat Owners Association of Australia (TBOAA). Tuna farms were a South Australian innovation, and it is possible—but not likely—that the Japanese really intended to raise southern bluefin tuna and “release them into the open sea.” As defined, however, the project was almost circular: breed SBT in captivity, release the juveniles into the wild, and then catch the juveniles and put them into pens to raise them to adult size so that they can be killed and shipped to Japan. Obviously, it would be less complicated to raise the tuna from eggs to adulthood in captivity, but that would require feeding them for eight years or more. It would be cheaper to let them feed themselves in the open sea, recapture them, and feed them for only a couple of years.
The 1991 breeding experiment did not work, and no spawning behavior was recorded, but the tuna farmers of Port Lincoln expanded their business exponentially anyway. (As we shall see, the profits made by at least one of the tuna-farming companies have encouraged them to try again to breed bluefins in captivity, but this time on a much larger scale.) Capturing half-grown tuna, fattening them, and selling them for exorbitant prices to Japan was a cash cow for tuna farmers but a tragedy for tuna. Southern bluefins were so overfished that they became scarce, and some of the larger tuna-fishing companies floundered. Joe Puglisi, now a retired tuna company owner (he sold Australian Bluefin in 2000 for $100 million), was the first commercial tuna farmer in South Australia. As the first president of TBOAA, he has participated in the rise and fall (and rise again) of the economic roller coaster that is the tuna-farming industry. I talked to this genial, white-haired man in his office in Port Lincoln. He claimed that others were taking credit for what he did. But he told me without rancor ($100 million does a lot to dispel rancor) how he had developed the “towing cages” that make the industry possible, and how his company had gone into receivership in October 1992, when “we almost lost everything.” With generous refinancing from local banks, however, Puglisi’s company bounced back, and within three months, they were out of receivership. In the 1980s, Puglisi was almost alone in supporting the idea of quotas as he was catching close to 20,000 tons in Port Lincoln at the time. If some restrictions weren’t in place, the area could become overfished, putting many commercial fisheries out of business. Once on the brink of failure because they were fishing the wild southern bluefins out of existence, tuna ranchers are now wallowing in money. Some of the money comes from the tuna farms, but the bulk of it comes from the individual ownership of quotas, parceled out to the tuna fishermen before the invention of tuna ranching in 1990. Tony Santic, a legendary tuna fisherman, reportedly sold 337 tons of his quota for $72 million, or $214,000 a ton. Even these men recognize that the tuna-ranching boom cannot last, so companies such as Clean Seas are investing heavily in projects designed to breed bluefins in captivity. In the meantime, the tuna millionaires are raking it in.
Port Lincoln is situated on one of the world’s largest protected natural harbors, encompassing Boston Bay, which covers an area more than three times the size of Sydney Harbor. The harbor was discovered by Matthew Flinders under his commission by the British Admiralty to chart Australia’s unexplored coastline in the ship Investigator. Flinders dropped anchor in Boston Bay in February 1802 and named the spot Port Lincoln after his native Lincolnshire in England. Initially considered as the alternative site for the state capital of South Australia, Port Lincoln was rejected in favor of Adelaide because Lincoln lacked an adequate freshwater supply. (Highways running south to Port Lincoln are accompanied by above-ground pipelines that bring in the city’s water.) Now home to Australia’s largest commercial fishing fleet, Port Lincoln has a thriving tuna-farming industry, but also aquaculture farms for kingfish, abalone, mussels, oysters, and, experimentally, seahorses and lobsters.
There are more millionaires per capita in Port Lincoln than in any other city in Australia, and most of them owe their success to the southern bluefin tuna. New houses, apartments, stores, marinas, hotels, restaurants, and shopping centers are being built at an astounding rate for a town whose population hovers around 14,000. Japanese dealers buy the entire catch of the Port Lincoln tuna fleet—often for astronomical prices. Japanese investments in the various tuna farms provided the capital to develop and implement the sophisticated technology that powered the industry. As the Port Lincoln tuna farmers (now fondly referred to as “tuna barons”) prospered, the Japanese were assured of an almost endless supply of the precious red belly meat of the bluefin tuna. It was a win-win situation—unless, of course, you were a fish.
In April 1996, South Australia’s tuna industry was crippled by a fierce storm that caused the deaths of thousands of captive fish that would have been worth more than $55 million. The fish, which were kept in floating pens and unable to escape the storm, were suffocated as their gills became clogged in swirling clouds of silt, excreta, and sediment. Between 65,000 and 75,000 tuna died, representing about half the population of Port Lincoln’s nine farms in Boston Bay. The mass deaths were a serious setback, but evidently not a lasting one for the booming Port Lincoln tuna-farm industry, which has grown at a phenomenal rate since the first experimental farm was established in 1991. The $100 million fish-fattening industry now comprises a whopping 60% of the Australian tuna industry’s 5,200-ton annual quota—and will probably rise even higher.
One unexpected outcome of the disaster of 1996, when most of the season’s harvest perished, was the export of Australian expertise to Croatia. When Australians of Yugoslav extraction (such as Dinko Lukin) learned about the tuna farming off Port Lincoln, they realized that there were bluefin tuna in the Adriatic too, and Croatian and Australian businessmen formed a consortium to bring this new industry to Croatia. Aussie divers, net makers, and fishermen advised the Croatians on the intricacies (and profitability) of tuna farming. By 1997, the Croatian version of Australian tuna farming was up and running. The bluefin tuna of the Mediterranean is not quite the same fish as the SBT—it is Atlantic bluefin tuna (ABT)—but it is similar enough that the same capture techniques can be applied to both species. Italy, across the Adriatic from Croatia, soon initiated its own tuna farming. By 2000, every country on or in the Mediterranean was catching tuna and putting them in offshore pens for fattening and sale to Japan. But the eastern Mediterranean is one of the two known breeding grounds for the Atlantic bluefin, and dozens of countries catching hundreds of thousands of half-grown tuna is the surest way to drastically deplete the population.
The Australian tuna-ranching industry has prospered wildly since its inception in 1991. In 2005 the southern bluefin tuna harvest reached 9,000 tons, the biggest to date. South Australia now has 15 southern bluefin tuna ranches, located primarily in two areas just east of Port Lincoln: Boston Bay and Rabbit Island. (This region is one of the most famous of all locales for great white sharks, and it is not unusual to find one of these man-eaters trapped in a tuna net.) Environmental groups have been lobbying for quotas, arguing that the very stock is threatened. But the tuna-ranching industry claims that a reduction in the catch would put people out of work, and besides, the status of the stock is fine. According to a 2006 report from the Australian Department of Agriculture, Fisheries, and Forestry, the southern bluefin tuna industry now earns an estimated $300 million annually.
Many kinds of fishes are commonly known as tunas: albacore, bigeye, dogtooth, yellowfin, skipjack, longtail, blackfin—and the bluefin, which comes in three varieties: northern (Thunnus thynnus), Pacific northern (Thunnus orientalis), and southern (Thunnus maccoyii). All tuna are scombrids, but not all scombrids are tuna. The family Scombridae includes several species of smaller, bullet-shaped fishes that are (correctly) grouped with the tunas, and also the mackerels, which are essentially smallish tunas without the heft, and without many of the advanced features that characterize the genus Thunnus. The blackfin tuna (Thunnus atlanticus), for example, is a small, typically shaped tuna, found only in the western Atlantic, from Martha’s Vineyard throughout the Caribbean, and along the coast of northeastern South America as far south as Rio de Janeiro. The maximum length is around 40 inches, and the all-tackle record (taken off Key West, Florida, in 1996) is 45 pounds 8 ounces. A pelagic (oceanic) schooling fish that feeds near the surface, the blackfin is blue-black on the back, with a golden yellow band that runs from eye to tail but fades out soon after death. Despite its small size, the blackfin is considered a world-class game fish.
The Spanish mackerels, kingfish, seerfish, and the wahoo—a large, elongated game fish famed for its speed and unwillingness to be landed—are also classified as scombrids. All scombrids are more or less pointed at both ends, with a crescent-shaped tail and a series of finlets on the dorsal and ventral surfaces of the hind end, aft of the second dorsal fin and just before the insertion of the tail fin. The function of these finlets is unknown, but because all scombrids are fast swimmers, they are believed to be somehow connected with speed. (The marlins, swordfish, and sailfishes are as fast as or faster than tunas, but although they have the same lunate tail fin, they lack finlets.) Below the big-tuna designations are several species of bonitos, “little tunas,” “bullet tunas,” “frigate tunas,” the kawakawa, and the cero. Most of the tunas are considered big-game fishes, worthy of being chased by fishermen in big expensive boats. But all the species that can exceed 20 pounds in weight are popular food fishes and are the object of some of the world’s most extensive fisheries. Some of the boats used in commercial tuna fishery are really big and expensive.
Large or small, cold-water or warm, all tunas have the same basic body shape (plump in the middle and pointed at both ends, rather like a football), generally considered the most advanced design for moving efficiently through the water. The pointy front end would encounter even less water resistance were it not for the tuna’s need to move water over its gills by keeping its mouth open. As Richard Brill and Peter Bushnell (2001) wrote, “tunas have high metabolic rates, and are obligate ram ventilators. They suffocate rapidly if prevented from swimming, so special care must be taken to ensure that ventilatory requirements are met during all stages of an experiment.”2 Because they depend on their own motion to pass oxygen-rich water over their gills, tuna can never stop swimming. When they are being as languid as possible, they must move a distance equal to their own length every second. They have no eyelids, so they can’t close their eyes, and because stopping is not an option, they might move autonomically through the water, “sleeping” as the water passes over their gills. All fishes need oxygen, which is absorbed into the gills, but oxygen requirements differ dramatically from species to species, depending on the fish’s lifestyle. The amount of gill surface on tunas is up to 30 times greater than that of any other fish. In some species, the oxygen-absorbing surface approaches that of the lungs of air-breathing mammals of comparable weight. To transfer oxygen from the gills to the bloodstream and thence to the other tissues, the heart of a tuna is, relative to the body weight, about ten times the size of that of other fishes. A tuna’s blood pressure and heart rate are about three times higher. Another factor in oxygen absorption is hemoglobin, the pigment that actually transports oxygen in the blood. The hemoglobin concentration in the blood of tunas is almost as high as it is in humans. A higher oxygen intake contributes to the tuna’s stamina and enables these superfish to undertake long-distance migrations, incredibly deep dives, and sprint speed that would do justice to a cheetah.
Also at the end, away from the tail—the cutwater, if you will—are the tuna’s large eyes. Unlike the eyes of many other fish species, the tuna’s eyes are flush with its head to enable it to pass through the water even more smoothly. The fins all fold flat against the body, and the first dorsal can be completely retracted into a slot. The scales of most tunas are so tiny as to be almost invisible; the great fishes slip through the water like polished torpedoes. All tunas have the same fin arrangement: a spiny, depressible dorsal fin; a second dorsal matched on the ventral side by the anal fin; and pectoral fins, used for steering and lift, that range from short in the bluefins and skipjacks to the long, knifelike blades of the albacore and yellowfins.
Bluefin Tuna
All the smaller tunas, such as skipjack, yellowfin, and albacore, are remarkably efficient animals and are as well-suited for their pelagic, predatory lifestyle as any marine creatures. But bluefins, the giants of the family, have taken every modification to the extreme.
The word “magnificent” is often applied to the bluefins, and it is exquisitely applicable. They are immensely powerful and fast, capable of speeds up to 55 mph. They are mature at about the age of 8, and individuals have been known to live for more than 30 years.
Bluefins spawn in April, May, or June in subsurface waters, but although spawning behavior has been observed in some of the smaller species, it has never been seen in bluefins. We do not know if they spawn once or many times in a season, or even if an individual spawns yearly. It is also unknown whether individuals can spawn in the east and then in the west at different times. Mature male bluefins are somewhat larger than females, which is different from the arrangement in billfishes, where the largest ones are always females. (Macho big-game fishermen such as Zane Grey and Ernest Hemingway went to their graves believing that all the big, tough, brave billfish and tuna they caught were males.) In the Western North Atlantic, bluefins mature by age 8. After examining the ovaries of 501 female bluefins from the Mediterranean, Aldo Corriero and (14) colleagues found that maturity for this “population” was reached between 4 and 5 years of age and a length of 54 inches. Females release millions of eggs, which are fertilized by males.
The spawning grounds for western Atlantic bluefins are in the Gulf of Mexico and the Mediterranean. (Spawning areas are identifiable by the presence of females with eggs ready to be broadcast and males with the sperm duct filled with spermatozoa.) Two of the Mediterranean spawning areas have been known for centuries: one just inside the Straits of Gibraltar, around the Balearic Islands, and the second in the Tyrrhenian Sea, from Sicily to the Gulf of Sidra (off Libya). It was not until well into the 21st century that a third spawning area was tentatively identified in the eastern Mediterranean between Turkey and Cyprus (Karakulak et al., 2004). Tagging results (such as Block et al., 2005) have shown that tuna have a definite “homing” instinct: bluefins hatched in a particular area return regularly to the place they were born. But many of the tagged fish do not show up in any of the known spawning areas, which raises a tantalizing question for researchers: Is there another breeding area for North Atlantic bluefins? Mather, Mason, and Jones suggested the possibility of a Gulf Stream spawning ground three decades ago, but so far, confirmation has not been forthcoming.
Tuna spawn only when the appropriate water temperature is reached, which ranges from 75°F to 79°F. For most species, spawning is restricted to warm, tropical waters with high salinity and strong current boundaries. For example, southern bluefins spawn only in a relatively small area off northwestern Australia in the eastern tropical Indian Ocean. Characterized as “reproductive broadcast spawners,” mature females lay millions of eggs over a period of months. The eggs are tiny, spherical, and transparent and contain a single oil globule to keep them buoyant. Only a very small percentage of the eggs survive. The larval tuna, which are 2 to 3 mm long, hatch in a few days and begin feeding on plankton smaller than they are. The great majority of larval tuna are eaten by larger predators. It has been estimated that fewer than one in a million survives.
Bluefin tuna migrate on a yearly cycle, arriving in the waters off the northeast coast of North America by June of each year and departing in late autumn. They can be found as far north as Newfoundland in the summer, and they are known to travel as far as 40° south of the equator during the winter. Northern waters provide the fish with rich feeding grounds, where they can grow and store fat as an energy source for migration. Each year, they return to their specific spawning grounds: the Gulf of Mexico and the Mediterranean. It was always assumed that there were two separate North Atlantic populations—one that spawned in the Gulf of Mexico and remained in the western quadrant, and another that spawned in the Mediterranean and swam around in the eastern part of the Atlantic. Starting in 1997, a research team led by Molly Lutcavage of the New England Aquarium in Boston satellite-tagged juvenile bluefins in New England and Canadian waters. The data they collected from the pop-up tags (meaning the tags were designed to pop off) revealed some surprising results. None of the tagged fish had appeared in either the Gulf of Mexico or the Mediterranean, the only known spawning grounds for bluefin tuna. It may have been nothing more complicated than that the timed release of the tags was insufficient to detect spawning, but it also might be that there is another breeding area in the central North Atlantic. If that is the case, the ramifications would be enormous. Management of the two North Atlantic stocks, already compromised by the tunas’ disinclination to remain in their half of the ocean, would be more than a little complicated if a third breeding population appeared on the scene.
A particularly disastrous alteration of the picture occurred in the waters off northeastern Brazil. Beginning around 1962, a fleet of Japanese longliners began fishing for tuna, and even though the operation was successful at first, it was suspended in 1967. Fromentin and Powers (2005) refer to this as the “Brazilian episode,” during which Japanese longliners caught 5,000 to 12,000 tons of Atlantic bluefin tuna (ABFT) in an area where they usually caught tropical tuna. This caused severe overfishing of the large bluefin tuna. Targeting mostly small bluefins, the Japanese took 1,160 tons in 1981 and 2,660 tons in 1982 and reached a high of 4,778 tons in 1992–1993 before quitting. It appears that longlining for bluefins is no longer conducted off Brazil because the big fish are gone. (In the northwestern Atlantic, however, where the biggest bluefins can still be found, fishing continues apace.)
Long thought to consist of localized, discrete populations, the ABFT is actually a single population. It has the “widest distribution of any tuna and is the only large pelagic fish living permanently in temperate Atlantic waters.”3 It now appears that the “giants” come to feed on herring and other small fishes off the coasts of North Carolina, Massachusetts, and Maritime Canada, and move on when the herring are gone. During the course of their wanderings, bluefins display a remarkable range of temperature preferences, from near-freezing waters when feeding (37°F or 2.8°C) to very warm temperatures when breeding (86°F or 29.5°C). Because we saw them there—sometimes feeding voraciously on those herring—we also assumed that ABFT were creatures of surface waters. Not necessarily. Pop-up tags revealed that these fish—ABFT, bigeye tuna, and swordfish—forage at heretofore unsuspected depths, to feed on the small creatures that make up the deep-scattering layer, or perhaps as a means of cooling their overheated bodies. The energy required to maintain a high body temperature is limited, and the tunas cannot remain at depths indefinitely. They have to rise into warmer waters to restore their thermoregulatory balance.
Bluefin tuna were not always venerated. Around the turn of the twentieth century, they were known as “horse mackerel.” They were considered a nuisance by herring or mackerel fishermen, because they sometimes followed the small fishes into the nets and, after eating their fill, tore their way out. Evidently the red meat was considered unappetizing then, for they were occasionally harpooned for oil when fish oil was a popular commodity. During the early decades of the last century, fishermen began harpooning the big ones, and landings in Maine and Massachusetts reached 94,000 pounds in 1919, 250,000 pounds in the 1930s, and 2 million pounds by 1948.4 Bluefin tuna are now fished around the world, but a large proportion of the fish caught off Maine, Massachusetts, and California are destined for Japan. North Atlantic bluefins use the Mediterranean as a spawning ground, and fishers from virtually every country with a shoreline on that inland sea catch the tuna there. Countries such as Spain, Italy, Greece, Tunisia, Libya, Malta, and Turkey are now “ranching” bluefins. They catch juvenile fishes and tow them to a pen, where they are fattened until they reach the size where they can be killed, frozen, and shipped to Japan. It is the Japanese sashimi market that sets the astronomical prices on these fish. They are the source of toro, the fatty belly meat that sells in Tokyo restaurants for the equivalent of $50 an ounce. When a big, top-quality tuna is caught in New England, Australia, or New Zealand waters, it may sell for $100,000 on the dock in Tokyo. By the time it is served in a restaurant, its value may have increased tenfold. Because of these prices, bluefins have been overfished, and their populations are threatened. But few effective protection measures have been taken, because doing so would require unprecedented international cooperation.
As mentioned, at one time it was believed that there were two separate populations of Atlantic bluefins: one that spent time along the east coast of the U.S. and offshore, and another that hung out in the eastern Atlantic and the Mediterranean. In those simpler times, Americans thought they should be able to catch the bluefins of the Western North Atlantic, and Europeans (along with Japanese, Chinese, and everybody else) thought the European tuna (which sometimes entered the Mediterranean) were theirs for the taking. A notable tagging program showed that the population structure was infinitely more complex than was previously thought, and that the Atlantic bluefins paid very little attention to which side of the ocean they were supposed to be on. (An analogous situation occurs in the Pacific. Bluefin tuna born off Japan sometimes swim to California, and if nothing interferes with their round trip (think Mexican purse seiners), they swim back to Japan.)
For purposes of “stock management,” the International Commission for the Conservation of Atlantic Tunas (ICCAT) divides the Atlantic tunas into two groups based on their known spawning areas. One group spawns in the Gulf of Mexico and the Straits of Florida (the spawning areas of swordfish, too), and the other group spawns in the Mediterranean. It was never obvious to ICCAT that the Gulf of Mexico is open to the Atlantic and the Caribbean (except along the Gulf Coast, of course), while the Mediterranean is a huge fish trap—hard to get out of once you’re in it—and that therefore the fisheries should be handled completely differently. (The first tuna ranchers, at Ceuta in Spanish Morocco, took full advantage of this fact. They set their trap nets in the 9-mile-wide passage that is the Strait of Gibraltar, snagging the post-spawning tuna on their way out of the Mediterranean.) In response to dwindling catches, ICCAT’s 22 member countries divided the North Atlantic into eastern and western sectors, each with its own quota. In 1991, when Sweden submitted a proposal to ICCAT that the bluefin be listed as endangered, it was immediately voted down by the U.S. and Japan, two countries with a strong economic interest in catching tuna. (Japan consumes 36% of all tuna—of all species—caught in the world, and the U.S. follows with 31%.) Conservationists, fishermen, and bureaucrats continued to draft proposals and position papers, while tuna populations plummeted and prices rose. As John Seabrook wrote in 1994, “One reason that the price is so high is that there are so few of them left in this part of the ocean, and one reason that there are so few of them is because the price is so high.”5 In 1995, a 440-pound bluefin tuna sold on the dock in Tokyo for $173,600. If someone is willing to pay $173,000 for a fish, a lot of fishermen will be looking to be the lucky one to cash in.
The tuna of the eastern zone, caught mostly by Europeans, are managed under a strict annual quota set by the European Union. Those of the western Atlantic, targeted by American fishermen, have been managed under strict catch quotas since 1995. Nevertheless, in both areas, the stocks of bluefin tuna have fallen dramatically. An 80% decline in the eastern (European) stock has been seen over the past 20 years, and a 50% drop in the western Atlantic population. ICCAT’s persistence in treating the “eastern” and “western” populations as separate stocks will only mean the continued and inexorable decline of Atlantic bluefin tuna. Because the fish of the western sector have been so heavily fished, they have received more of the benefits (such as they are) of ICCAT protection. The recent quotas of 3,000 tons in the western North Atlantic (compared with 32,000 tons in the east) will not benefit the western population if the fish are regularly venturing into the more heavily fished eastern regions. Until ICCAT recognizes that the ABFT is composed of a single, mixed population, the numbers will continue to plummet.
Because of the prices they can fetch, bluefins have been overfished, and their North Atlantic breeding populations are estimated to have declined about 90% in the last 20 years. As with all fish populations, exact counts are impossible. Therefore, to no one’s surprise, there are vast gaps between the high estimates, made by the fishermen, and the low estimates, made by those who would protect the tuna from overfishing. From dock to cabinet ministry, there have been endless discussions about solving the problem at every level, but few protective measures have been taken, because doing so would require unprecedented domestic and international cooperation.
Fisheries management is a fine and noble goal, but there has to be something left to manage. During the 1960s, bluefin catches peaked at about 35,000 metric tons, but less than a decade later, overfishing sent the catch plummeting to less than half of that figure. A 1964 peak of 20,000 tons in the western Atlantic fell to 6,100 tons in 1978. The collapse of the New England tuna fishery has been comprehensively documented, most eloquently by Carl Safina in his 1997 Song for the Blue Ocean, but where the big fish were before they arrived off Georges Bank is still a mystery. The same is true of the massive schools of tuna that every year entered the bottleneck of the Straits of Gibraltar and swam into the Mediterranean, the functional equivalent of a gigantic fish trap. Somehow, the size, speed, and range of the great bluefins have kept much of their life history hidden from the prying eyes of researchers. Through great advances in tags and tagging techniques, we have been able to follow individual bluefins in the Atlantic and the Mediterranean. We are just beginning to get an idea of where they go and when.
How and where they are fished is also an issue. Unlike some other tuna fisheries, bluefin tuna in the Mediterranean are predominantly harvested by purse seine vessels. The good news is that this type of gear has relatively little bycatch. The bad news is that the illegal use of spotter planes makes it so easy to locate and capture schools of tuna that hardly any escape. Recent years have also witnessed tremendous modernization of the Mediterranean’s purse seine fleet, with larger, faster vessels outfitted with the latest in fish-finding technology. These vessels are so effective that traditional fishing grounds in the western Mediterranean have been depleted and abandoned in favor of high densities of spawning fish in the eastern Mediterranean.
At the heart of the problem is the rapid development of commercial tuna farming operations throughout the Mediterranean. Beginning as early as 1991, these tuna farms were not true aquaculture operations that produce fish from spawning individuals. They are more accurately termed “fattening operations,” where tuna captured by purse seine vessels are transferred to floating cages. Tuna are caged anywhere from several months to several years, where they are fed to increase their fat content and improve the color of the flesh in order to better meet Japanese market standards. Nothing more and nothing less than a tuna feedlot.
This is a problem, because roughly 10 to 25 kilograms of baitfish are necessary to produce 1 kilogram of tuna. Therefore, the fattening operations are grossly inefficient. In addition, the number of illegal, unregulated, and/or unreported (IUU) catches has increased dramatically. Purse seine vessels no longer need to land their catch at port, but instead transfer live tuna to cage operations directly at sea. Indeed, even fish that are not destined for fattening are also directly transferred to floating cages called “tuna hotels,” where they are slaughtered at sea and processed or blast-frozen. Some estimate that up to 50% of the Mediterranean’s total bluefin catch may be IUU. Ultimately, a World Wildlife Fund (WWF) study reported that the increase of IUU catches, exacerbated by the popularity of tuna farms, may have generated a total catch in excess of 45,000 metric tons. This catch is 40% above the 32,000 metric tons quota set by ICCAT, which itself is 23% higher than the total quota recommended by scientists. The harvest of Mediterranean bluefin tuna stock is 63% higher than what the best science suggests.
As mentioned earlier, bluefin tunas come in three varieties: the northern (Thunnus thynnus), which breeds in the Gulf of Mexico and the Mediterranean and cruises the North Atlantic; the Pacific northern (Thunnus orientalis), which breeds in the waters of northern Japan and crosses the North Pacific; and the southern (Thunnus maccoyii), which breeds in the waters north of Australia and south of Indonesia and can be found throughout the Southern Ocean. All three look very much alike, except that the northern version grows the largest—particularly in the waters of eastern Canada and New England. Because the three species do not mingle or interbreed, they are mostly differentiated by geography.
Pacific Bluefin Tuna
The species now known as Thunnus orientalis is the Pacific northern bluefin tuna. It’s found primarily in the North Pacific from Japan to California (spawning in the vicinity of Japan), although specimens have also been taken off South Africa, western Australia, New Zealand, and the Galápagos Islands.
The three species of bluefin—southern, northern, and Pacific northern—have long been held to be separate. The true northern bluefin (Thunnus thynnus) does not visit the southern Pacific, so there is little chance of finding one off of Australia. As for the other two, the visible differentiating factors appear to be yellow versus blue caudal keels and yellow versus blue finlets.
Even though it breeds close to the islands of Japan, making it susceptible to a local fishery, the Pacific tuna population appears to be the only one of the three bluefin species that has not been severely overharvested. There is currently no management of bluefin in the north Pacific, a cause for worry given the status of the other populations. At present we know little about the movements of bluefin in the eastern Pacific, especially the larger animals. Based on the available information, we can conclude that bluefins appear to spawn only in waters off southern Japan, and that late in their first year, some individuals swim east. Data suggests that when the sardine population off of Japan diminishes, bluefin leave the area. Off the coast of Mexico and California, bluefin are most abundant in the summer and fall months, after which they seem to disappear.
Since 1952, the total catch for the whole Pacific Ocean has fluctuated between 10,000 and 35,000 tons, peaking around the 1980s, dropping off in the ’90s, and climbing again at the beginning of the 21st century. By far the largest proportion was taken by Mexican purse seiners in the western Pacific, but there is also a Japanese longline fishery, as well as a purse-seine fishery that targets skipjack, yellowfin, and Pacific bluefins. The bluefins are not the most important product of this fishery by weight, but they are worth more because of the sashimi market. Unsurprisingly, the Japanese dominate this fishery, but the Taiwanese took nearly 3,000 tons in 1999.
Southern Bluefin Tuna
The southern bluefin tuna (Thunnus maccoyii) is a large, fast-swimming, pelagic fish found throughout the Southern Hemisphere mainly in waters between 30° and 50° South, but only rarely in the eastern Pacific. Some consider it a subspecies of the northern bluefin, which is technically known as Thunnus thynnus. The northern variety, found in all the temperate and tropical waters of the world—except the high southern latitudes—looks very much like the southern, but it gets much larger. (The International Game Fish Association (IGFA) record for a southern bluefin is 436 pounds; the record northern was a thousand pounds heavier.) Except for size, though, the difference in the two species of bluefin tunas is miniscule.
As early as the 1950s, the Japanese were catching Thunnus maccoyii in the northeast Indian Ocean. Southern bluefins proved to be so valuable that soon the Japanese expanded their operations to South and Western Australia. The tuna that are caught are frozen at very low temperatures (–60°C) and are either unloaded at intermediate ports and shipped to markets in Japan or are shipped directly to markets in Japan. From 1988 to 1995, a number of Japanese longliners (also catching yellowfin tuna, bigeye tuna, albacore, swordfish, and marlins) entered into a joint-venture agreement with Australian companies. But these agreements ended when the Australians switched over from pole-and-line fisheries to the purse seining (Robins and Caton, 1998). The Australian component of the fishery now uses purse seines to enclose a school of fish and then tows them to waters near the Australian mainland. There they are transferred to floating cages anchored to the ocean floor. The tuna are then fattened for several months and sold directly to Japanese markets as frozen or chilled fish. Because of the fishes’ high fat content, premium prices can be obtained for toro in Japan. Australian tuna farmers boosted production from 140 tons in 1992 to more than 4,700 tons in 1998. The total value of the southern bluefin fishery is now estimated to be about AUS$1 billion.
Until recently, the only countries fishing the southern bluefin were Australia and Japan. The Australians used pole-and-line, purse seines, and trolling gear, but the Japanese used only longlines. In the 1950s, the annual catch of southern bluefin tuna (SBT to fisheries biologists) was 12,000 to 15,000 tons, and the fish was used mostly for canning. Heavy fishing pressure resulted in a significant decline in the numbers of mature fish, and the annual catch began to fall rapidly. It became apparent that the SBT stock was at a level where some kind of management and conservation were required. In 1985, Australia, Japan, and New Zealand, the main nations fishing southern bluefins at the time, began to apply strict quotas to their fishing fleets. In May 1993, the voluntary management arrangement between the three countries was formalized with the creation of the Convention for the Conservation of Southern Bluefin Tuna (CCSBT). Other fishing nations, such as Korea, Taiwan, and Indonesia, were active in SBT fishery, which reduced the effectiveness of the members’ conservation and management measures. Of course, new counties trying to take advantage of the rich Japanese market caused the stocks to decline again. As a matter of policy, the CCSBT encouraged the membership of these countries. On October 17, 2001, the Republic of Korea joined the Commission, and Taiwan’s membership became effective on August 30, 2002. Indonesia was accepted as a formal cooperating nonmember on August 2, 2004.
Not long after the formation of the CCSBT, the organization was called upon to adjudicate a conflict between the original signatories of the Convention, with Japan on one side and Australia and New Zealand on the other. Because the southern bluefin is a highly migratory species, it passes through the exclusive economic zones of several countries in the Southern Ocean. The Commission was formed because it was recognized that the stock was declining precipitously, and action was necessary by the countries that were actively fishing on the only population. Instead of cutting back, however, Japan began a no-limit “experimental” fishery in 1998 and took 1,400 tons over its assigned quota. In protest, Australia banned Japanese fishing boats from visiting Australian ports. (Not unlike “scientific research whaling,” the Japanese experimental tuna fishery was nominally conducted for scientific purposes, but somehow, the meat ended up in fish markets and supermarkets.) This effectively shut down the lucrative arrangements between Japan and Australia for Japanese freezer ships to pick up the frozen tuna (farmed and wild-caught) that the Australians were consigning to Japanese markets. Australia and New Zealand requested an injunction under the International Tribunal for the Law of the Sea (ITLOS), and the tribunal suggested binding arbitration. An agreement was reached in May 2001 whereby Japanese ships were once again allowed into Australian ports and the Japanese agreed to substitute a limited scientific research program for their unrestricted “experimental” fishery.
Although management restrictions under the CCSBT have been in place for more than 10 years, the SBT biomass (total weight of fish) has continued to decline. The parental biomass is currently estimated at less than 10% of the 1960 level, well below what is considered a biologically safe level. Annual catches for countries operating outside the restrictions of the CCSBT, such as Korea and Indonesia, are probably on the order of 2,500 tons, and China is expanding its distant-water fishing fleet. According to the International Union for Conservation of Nature’s (IUCN) Red List of Threatened Animals, the southern bluefin tuna is “critically endangered,” which is defined as “facing an extremely high risk of extinction in the wild in the immediate future.” In a 1997 TRAFFIC report on the southern bluefin tuna fishery, Elizabeth Hayes wrote, “The collapse of significant fisheries in the past several decades has indicated that it is possible to fish marine species to commercial extinction and that great economic suffering occurs as a result. If the warning signs are ignored, this possibility exists for SBT.”6
In August 2006, an Australian investigation revealed that Japanese tuna boats, along with Taiwanese and Thai fishers, had been secretly taking more than twice the CCSBT quotas for the past 20 years and bringing the fish into Japan without reporting the actual catch. The discrepancies were first noticed by the Australian Tuna Boat Owners Association (ATBOA) when they saw “irregularities” in Japanese records of the fish caught in the Great Australian Bight. Japan had agreed to a 6,000-ton annual quota, but investigators learned that the country had been taking 12,000 to 20,000 tons every year for 20 years and hiding it.
The Japanese allowed only Japanese observers on their boats, so there was no one to report the excessive tonnage or the misrepresentation of the species. Some of the fish being delivered to Tokyo fish brokers as “bigeye tuna” were actually southern bluefins. Also, tens of thousands of tons of SBT were never entered in the Japanese public auction system, but were sold directly to retailers instead.
Following the revelations of Japanese overfishing, a CCSBT meeting was held in October 2006 at the Japanese tuna port of Miyazaki. Australian delegation leader Glenn Hurry announced that the 178,000 tons of SBT taken by the Japanese was actually worth $8 billion, not the $2 billion that had been previously estimated. The Australian delegation proposed that the Japanese annual quota, which was at 6,065 tons, be reduced to 3,000 tons. It is obvious that 10 years of flagrant disregard of quotas and regulations by the Japanese has been a major factor in the decline of southern bluefin stocks. It remains to be seen whether reduced quotas will enable the stock to recover. (Or if the Japanese intend to abide by the new quotas.)
Yellowfin Tuna
Yellowfins (Thunnus albacares) are probably prettier than bluefins and are more widely distributed, so more of them are caught commercially. With its extremely long, canary-yellow second dorsal and anal fins, the yellowfin is easily differentiated from other tunas. The pectoral fins, which also become yellow in adult fish, are very long, reaching to the base of the second dorsal. The finlets between the fins and the tail are also bright yellow. The most brilliantly colored of the tunas, the yellowfin is metallic blue or greenish-black above and pearl-white below; in younger fish, the lower flanks are crossed with interrupted vertical lines. Adult fish have a band of bright gold or iridescent blue (sometimes both) running along the flank. Spawning yellowfins have been observed to “flash” their colors, perhaps as a stimulant to the opposite sex. Conversely, dying tuna begin to lose their bright coloration and soon fade to shades of dull gray.
Spawning takes place twice a year and requires a water temperature of at least 79°F. At the Achotines Laboratory in Panama, efforts have been under way for several years to breed yellowfin tuna in captivity. Established in 1985 as part of the Inter-American Tropical Tuna Commission’s (IATTC) Tuna-Billfish Program, the Achotines Lab is one of the few research facilities in the world designed to study the early life history of tropical tunas, particularly yellowfins. The laboratory is adjacent to Achotines Bay on the southeastern tip of the Azuero Peninsula on the Pacific side of the Republic of Panama, where the annual range of sea-surface temperature is approximately 21°C (70°F) to 29°C (84°F), ideal for spawning tuna. (The Azuero Peninsula is known to big-game fishermen as “the Tuna Coast” because of the yellowfin tuna, but also because it is the home of world-class blue, black, and striped marlins, as well as sailfish, dorado, and wahoo.) The continental shelf off Achotines Bay is quite narrow. The water reaches depths of over 600 feet less than 5 miles from shore, affording scientists ready access to oceanic waters where spawning of tunas occurs during every month of the year. Because little is known of the reproductive activities or early life history (egg, larval, and early-juvenile stages) of the various tunas, the IATTC established a research laboratory to focus on these aspects of tuna biology.
In 1992, IATTC scientists at Achotines began a joint project with Japan’s Overseas Fisheries Cooperation Foundation to encourage breeding, spawning, and raising of tuna in captivity. From the program’s inception in 1993 until its conclusion in 2001, several Japanese scientists were based at Achotines, working with IATTC personnel on the complex problems of breeding captive tuna. The tanks at Achotines held yellowfin tuna in virtually every stage of development, from floating eggs and inch-long larvae to 150-pound adults in the large tanks, which are 6 meters (20 feet) deep and 17 meters (45 feet) in diameter. Upon the Japanese departure in 2001, the facilities and equipment (much of which had been provided by Japan) became the property of the Republic of Panama and remained at the laboratory for use by IATTC scientists.
A captive population of 44 yellowfins first spawned in October 1996, which involved only two or three pairs of the largest fish. From the Achotines website: “Yellowfin tuna in the main broodstock tank have been spawning almost daily since October 1996, the only successful spawning of yellowfin in land-based tanks anywhere in the world. Spawning generally occurs from early afternoon to late evening.” As Kurt Schaefer (2001) described it, “Each spawning event occurred around sunset, and was preceded by courtship behavior during the late afternoon. The courtship behavior included pairing of individuals, chasing, rapid color flashes exhibited by individual fish, and rapid horizontal or vertical swimming. During the following 3 months of 1996 spawning was continuous, with many of the fish exhibiting courtship behavior prior to each spawning event.”7 The numbers of fertilized eggs collected after each spawning event in the main broodstock tank range from several hundred to several million. The eggs are collected by several methods, including siphoning, dipnetting at the surface, and seining with a fine-mesh surface egg seine. Fertilized eggs are hatched in 300-liter (78-gallon) cylindrical incubation tanks.
Like many fish species, yellowfins are compulsive schoolers, but they often swim in mixed schools with skipjack, bigeye, and other tunas. Curiously, their association with dolphins has been observed only in the eastern tropical Pacific and not in the western Pacific, Atlantic, or Indian Oceans. But wherever yellowfins congregate, they are targeted by commercial fishers. Hundreds of thousands of tons are harvested annually, making yellowfin one of the most important of all commercially caught tunas. They are caught by longliners and pole-and-line bait boats, but the purse seiners figured out how to exploit the yellowfins’ habit of aggregating under objects at the surface—particularly schools of dolphins. We don’t know why they do this, but the habit has proven disastrous for millions of tuna (and dolphins). As tuna fishermen found their prey by spotting dolphins at the surface, and when they set their set their deep-water purse seines around the dolphins, they also caught the tuna, the object of the fishery in the first place. In addition to its desirability as a commercial species, Thunnus albacres is one of the world’s most popular game fishes.
Yellowfins are found in every ocean (except the Mediterranean) in a wide swath between 45°N and 40°S. At least some of the stocks are migratory. Because of their size and strength, yellowfins are still highly regarded as game fish. Few other species can reach their size and put up such a fight. Therefore, they are among the primary objects of sport fishing clubs around the world. In Fishing in Bermuda, James Faiella wrote: “The yellowfin is considered the most prized of all tuna varieties both around Bermuda and elsewhere for their size, gameness, and the high quality of their flesh.”
For example, Tuna Club members in Catalina, CA, caught a total of 6,532 tuna in 40 years. The best year was 1919, when 911 were taken. Tuna Club members could have caught 10 or a hundred times the number they caught over the years, and they wouldn’t have come close to the numbers of yellowfins taken by commercial fishers in a given year. In just one part of one ocean, according to a 2002 report in Pacific magazine by Robert Keith-Reid:
...the annual yellowfin catch first exceeded 200,000 metric tons in 1980. By 1990 it had almost doubled to 380,000 metric tons. In the past four years it exceeded 420,000 metric tons with a peak of 480,000 metric tons... Tagging of yellowfin in the early 1990s, when catches were 10 to 20 percent below present levels, indicated that the stock was not being overfished. But recent research shows that the stock has suffered a “significant” decline of about 35 percent since 1997. The decline is most evident in the western equatorial Pacific where the stock is estimated to be down by more than 50 percent since the mid 1990s. For the whole Western Pacific, the stock is estimated to be 30 percent below what it would have been had it not been fished.8
After skipjack, yellowfin is the second-heaviest-fished tuna. Like skipjack, it is canned and marketed as “light” tuna, but it is also an important component of sushi and sashimi. (The only tuna that can be labeled “white” is albacore.) When cooked, yellowfin meat is firm and mild-tasting and tends to be light yellowish-brown in color. In larger fish (20 to 30 pounds) the meat tends to become slightly darker and dryer. A report issued by the Japanese Fishing Authority (Anonymous, 2005) analyzed recent trends in tuna fishing in the Western and Central Pacific. In 2004, 1,447 longliners, 176 pole-and-line boats, and 54 purse seiners accounted for 31,717 tons of bigeye tuna, 41,406 tons of yellowfin, and 303,127 tons of skipjack. By an order of magnitude, skipjack is the predominant tuna species caught in the Pacific (and elsewhere), but yellowfin catches continue to rise. Most skipjack is canned, but more and more yellowfins are destined for Japanese restaurants, which are on the increase around the world. Charts with numbers usually cause the MEGO (My Eyes Glaze Over) syndrome, but I think the numbers tell a particularly important story about tuna fishing. Table 4.1 lists the number of catches of various tuna species in the Pacific. (Figures are in tons. I have included only a few years to show trends.)
Table 4.1. Catches of Various Tuna Species in the Pacific
Try to imagine what a million and a half tons of skipjack looks like. Or “only” three-quarters of a million tons of yellowfin. Recent analyses suggest that yellowfin is exploited to its optimum in the eastern Pacific Ocean and that no significant growth in volume will occur in the future in the western Pacific. In the Indian Ocean, exploitation leaves little room for a population increase. Although the yellowfin is not considered endangered, there is general concern that the increased catches of juvenile yellowfin (especially in the Atlantic, Indian, and western Pacific Oceans) will cause the stocks to suffer in the long term.
For the most part, the behavioral traits of wild animals have evolved to be beneficial to the species. Herding, flocking, or schooling, for instance, may be seen as stratagems to protect a given individual by offering too many choices to potential predators. Ultimately, of course, the predators evolved counterstrategies that enabled them to select one animal out of the school or herd and focus on that one to the exclusion of the others. Lions select one zebra out of the herd and chase only that one, ignoring other zebras galloping by—even those that cut in front of them. Longline fishing, where hundreds of miles of baited hooks are deployed, depends to a certain extent on the gregarious behavior of the target species. If tuna were not schooling fishes, not enough of them would take the baits deployed on the lines, and there would be no point in fishing for a given species in a particular place. The schooling yellowfins that so enraptured Zane Grey have another trait that ultimately have proven to be their undoing. They tend to aggregate near or under floating objects that can be as insignificant as a floating log, as large as a ship, or as active as a group of dolphins.
For reasons that are still unknown, yellowfins aggregate under schools of spotter and spinner dolphins in the eastern tropical Pacific, west of Central America and Mexico. In the 1960s, tuna fishermen out of San Diego learned that they could locate schools of yellowfin tuna by scanning the horizons for disturbances on the surface made by herds of leaping dolphins. In “setting on dolphins,” a school of dolphins is rounded up like cattle by small outboard-motor speedboats. After the dolphins and tuna are encircled together, the net is closed (“pursed”) at the bottom by a cable and rings. Then the net with the tuna and dolphins in it is brought aboard by a hydraulic power block. One set could net anywhere from 10 to 100 tons of tuna, a much more productive method of fishing than the old hook-and-line bait fishing. Production increased dramatically, but so did dolphin mortality. According to a 1986 study by N.C.H. Lo and Tim Smith, “the annual kill from 1959 to 1972 varied from 55,000 in 1959 to 534,000 in 1961. There were three distinct maxima of 534,000, 460,000, and 467,000, corresponding to peaks in the number of sets made on dolphins in 1961, 1965, and 1970. The total kill from 1959 to 1972 was estimated to be about 4.8 million.”9
A great environmental outcry resulted in the passage of the Marine Mammal Protection Act in 1972, which made it a violation to harm any cetacean. But tuna fishermen lobbied for an exemption, and they continued to kill dolphins in staggering numbers. More than 300,000 died in 1972. Fishermen continued to set their nets on dolphins until they were sued in federal court by a consortium of conservation groups and forced to suspend their entire fishing operations. They were allowed to commence again only if they could abide by strict quotas imposed by the government, which were to be decreased annually to allow the fishermen to adjust to the new regulations. The first new quota, set in 1976, allowed the fishermen to kill 78,000 dolphins. The number was steadily reduced until it stood at 20,000 by 1981. In 1990, the StarKist Seafood Company (a subsidiary of the conglomerate H.J. Heinz) announced that it would no longer purchase tuna that had been caught with dolphins. StarKist began to label its cans of tuna “dolphin-safe.” BumbleBee and Chicken of the Sea quickly followed suit. Because these three companies accounted for more than 80% of the tuna sold in the U.S., the dolphins were spared—for the moment, anyway.
In 1991, Mexico complained under the General Agreement on Tariffs and Trade (GATT) dispute settlement procedure. The dispute ended with the U.S. not being allowed to set an embargo on imports of tuna products from Mexico just because Mexican regulations on the way tuna was produced did not satisfy U.S. regulations. The report was never adopted, so Mexico and the U.S. held their own bilateral consultations aimed at reaching an agreement outside GATT. The outcome of the consultations was the Agreement on the International Dolphin Conservation Program (AIDCP), put into force in 1999. By the end of December 2002, the U.S. Department of Commerce ruled that encircling dolphins with nets a mile wide to catch tuna would not significantly harm them, through the implementation of the measures set forth by the AIDCP. Should all encircled dolphins be safely rescued from the nets, the tuna could be marketed as dolphin-safe. The previous definition of “dolphin-safe,” introduced by the Earth Island Institute, excluded the labeling of “dolphin-safe” for any tuna caught by using the practice of encircling.
In 1994, President Bill Clinton signed into law the North American Free Trade Agreement (NAFTA), removing any restrictions on trade between the U.S., Canada, and Mexico. Under the terms of the MMPA of 1972, American fishermen could not fish in the eastern tropical Pacific without employing devices and procedures that would reduce the dolphin kill. But foreign fishers were not obligated to adhere to American restrictions and therefore could fish any way they wanted—including “setting on dolphins.” The U.S. government concluded that circling dolphins in nets was harmless and threw open the door to allow Mexican fishers to sell tuna in the U.S. under a “dolphin-safe” label.
Further exploiting the inclination of tuna to aggregate, fishermen—particularly those in the South Pacific who fished for yellowfin and bigeye tuna—developed primitive devices that would attract the fish so that they could be caught. Indonesian and Philippine fishermen used floating rafts of bamboo or palm fronds, moored to the seafloor and weighted down with baskets of stones. The fish were speared, netted, or caught on hand lines. It was only a matter time before someone realized that attracting fish with one device and catching them with another was redundant, and “vertical longlining” was born. (“Horizontal longlining” is the traditional method of playing out mile after mile of lines and attracting the fish—and everything else—to the baited hooks.) Combining the best features of fish aggregation devices (FADs) and longlines, this system consists of cables or ropes supported at the surface by floats, moored to the bottom with chains and anchors. Each suspended line is rigged with branch lines that are festooned with baited hooks that are designed to attract different-sized fish at different depths. The vertical longlines, therefore, are themselves FADs.
For the benefit of fishermen who want to try this new technique, the Coastal Fisheries Programme of the Secretariat of the Pacific Community (SPC) prepared a detailed manual, explaining everything from rope-splicing and knot-tying to the selection of bait (and how to catch it) for various targeted species. “Fish aggregating devices,” reads the introduction, “are floating rafts or buoys anchored in deep water which, for reasons not yet fully understood, cause tuna and other types of oceanic fish to gather around them... This fishing method, which had now [1998] become known as vertical longlining, is still evolving, with SPC continuing its work on streamlining the gear and increasing the number of hooks that can be concentrated within a particular area.” The manual, titled “Vertical Longlining and Other Methods of Fishing around Fish Aggregating Devices”10 (Preston, Chapman, and Watt, 1998), also details other methods of fishing around FADs. This includes the Hawaiian night-fishing method called ika shibi (“squid-tuna”) because it was developed to catch the tuna that were attacking the squid that the Hawaiians were trying to catch. In ika shibi, underwater lights are used to attract small squid, which in turn attract the tuna, now the object of the fishery. The SPC report concludes:
Vertical longline fishing around FADs can be a productive and potentially lucrative activity. It allows fishermen to target abundant resources of coastal tunas using small boats and simple, relatively inexpensive gear. Where cash markets for fish are well-developed, good-quality fresh tuna can command premium prices. Provided they look after their catch properly, fishermen carrying out vertical longlining around FADs can target this market and make much greater profits than they could from many other styles of fishing.
Fish that are brought out of the water quickly suffocate, and yellowfins caught by South Pacific fishers certainly could not be left on deck to die in the sun. To help fishers solve this problem, the SPC published a booklet called “Onboard Handling of Sashimi-Grade Tuna.” It succinctly explains how to gaff the tuna (“Never gaff the fish in the body, the throat, or the heart”), how to kill it (“stun the fish with a sharp blow to the top of the head, and then insert a spike into its brain”), how to bleed it (“When the tuna is struggling in the water... the blood attains a high organic waste (lactic acid) content and raises the temperature. Bleeding removes the organic waste and helps cool the fish’s body”), how to clean it (“carefully rinse the fish inside and outside”), and how to chill and store it (“place it in a slurry of flake ice and sea water... protect the fish in a gauze sock or a plastic body bag... lower it gently into a refrigerated seawater tank.”). The booklet concludes with this admonition: “No matter what methods of handling and presentation are requested by the buyers: always kill, bleed, and chill tuna that weigh over 25 kg as quickly as possible!”
Albacore
Identifiable by its winglike pectoral fins that reach beyond the anal fin, the albacore (Thunnus alalunga) is a medium-sized tuna that inhabits the temperate and subtropical waters of the world. They have a maximum life span of about 20 years, by which time they may reach 52 inches in length. (The present rod-and-reel record is 88 pounds.) Unlike some of the larger tunas, which are deepest in the region of the first dorsal fin, the albacore’s greatest body depth is just forward of the second dorsal fin. Sport fishermen troll for albacore with feathered jigs, spoons, and lures or bait their hooks with mullet, sardines, squid, herring, anchovies, or any other available small fishes. Albacore is one of the world’s most important food fishes and is the only tuna that can be labeled “white meat” on the can. It is commercially caught by trolling jigs behind a slow-moving boat, although other nations employ purse seines and longlines.
Albacore fishery is international, with fleets operating in most of the major oceans of the world. Albacore typically are caught between latitudes 10° and 45° both north and south of the equator, with most being taken on the high seas. The South Pacific albacore stock extends from the East Coast of Australia to the West Coast of South America. The longline fleet normally targets adult fish that are usually found in the surface mixed layer, but they have been caught as deep as 1,500 feet. Thunnus alalunga is a highly mobile species that moves throughout a very wide area of the South Pacific. While albacore travel in schools that generally are less dense than those of skipjack and juvenile yellowfin. Consequently, the commercial fishery is largely limited to longline or trolling.
According to a 2005 report by John Childers and Scott Aalbers of the National Marine Fisheries Service (NMFS) Southwest Fisheries Center at La Jolla, California, the U.S. troll-fishery in the North Pacific accounted for approximately 64,000 tons of albacore. This is approximately 20% of the total North Pacific catch of albacore; the Japanese account for another 73% of the total 320,000 tons, or 233,600 tons per year. The Japanese employ a pole-and-line fishery in the spring that targets two- to five-year-old fish off the Japanese coast eastward to the Emperor Seamount chain. There are also Japanese, Taiwanese, and South Korean longline fisheries, which harvest albacore in subtropical and temperate waters across much of the Pacific during the winter. Beginning in the early 1980s, Asian high-seas drift gillnet fisheries targeted two- to four-year-old albacore across much of the Pacific, but driftnets have supposedly been outlawed. There is a relatively small Canadian troll fishery for albacore during years when they appear in the waters off British Columbia.
The IUCN has not reassessed albacore in over 10 years. The last assessment (1996) was “data deficient,” meaning that a population estimate is not possible. Assessments of the stocks of the North and South Atlantic from the same period showed them to be vulnerable and critically endangered, respectively, because of “actual or potential levels of exploitation.” The North Pacific albacore population is considered a healthy stock at this time. It is considered an “eco-friendly” fishery in that there is very little bycatch and no impact on fishery habitat. Also, unlike some other tuna species, albacore do not swim with dolphins, so no albacore fishery is associated with dolphins. The NMFS considers the North Atlantic albacore population overfished, with overfishing still occurring, but the southern Atlantic stock is not considered overfished.
“Troll-caught” albacore are between 3 and 5 years old, harvested by trolling artificial lures with unbaited hooks behind a slow-moving boat. Commercial fishermen in North America have used this low-impact, environmentally responsible fishing technique to catch albacore for nearly a century. Albacore fishing fleets from other countries tend to use other fishing methods. Those who advocate the consumption of albacore maintain that younger troll-caught albacore contain more beneficial omega-3 fatty acids than older, larger albacore more commonly available on the market. Processing techniques also affect the omega-3 content of canned albacore. Most canned albacore sold by the big major brands comes from older, larger albacore, which is cooked twice during the canning process. Some fishermen now offer custom-canned troll-caught albacore, hand-packed and cooked just once to prevent the loss of omega-3s.
Regardless of where (or how) it is caught, most albacore ends up in cans in the U.S. In Japan, shiro maguro (literally, “white tuna”) is uncommonly served as sushi or sashimi because the meat is so soft that it is difficult to handle. Moreover, albacore accumulates higher levels of mercury than other kinds of tuna, and some groups have urged testing and recall of canned albacore with high mercury levels. Longlined albacore are older fish and have accumulated more mercury than younger, troll-caught fish. The U.S. Food and Drug Administration (FDA) advises women of childbearing age and children to limit their consumption of albacore tuna (chunk white canned tuna) and tuna steaks to 6 ounces per week or less.
Bigeye Tuna
The large eyes of this species suggest that it lives and hunts at greater depths than other tunas. Bigeyes reach a maximum length of 7½; feet and can weigh 400 pounds. (The record is a 435-pounder caught off Peru.) Whereas the body of a bluefin is deepest around the middle of the first dorsal fin, the bigeye is deepest just forward of the second dorsal. (It is believed that the specific name obesus is derived from the depth of the body.) Bigeyes resemble yellowfins—they are both called ahi in Hawaii—but Thunnus albacares has yellow, scythelike dorsal and pelvic fins, and Thunnus obesus has longer pectoral fins and a proportionately larger head. Like most of the large tunas, the bigeye is metallic blue-black above and silvery-white on its flanks and belly, with pale vertical striping.
Bigeyes are among the most commercially important tunas, especially in Pacific Rim countries such as Japan and Australia. They are usually caught on longlines, not in nets, and are sold fresh, not canned. The bright-red meat, higher in fat than that of other large tunas, is prized for sashimi and grilling. Bigeyes are found all over the world in tropical and subtropical waters, and they are popular big game fishes on both coasts of North America, in Hawaii, and in Australia. Among the countries catching bigeye tuna, Japan ranks first, followed by the Republic of Korea with much lower landings. The world catch increased from about 164,000 metric tons in 1974 to 201,000 tons in 1980, reaching a peak of 214,000 tons in 1987. In the Indian Ocean, the bigeye tuna fishery was dominated by Japanese fleets up to the end of the 1960s, but as operations of vessels from Korea became more important, they accounted for more than 60% of the catch in the late ’70s. The most important fishing gear in the Pacific are longlines, which comprise some 400 “baskets” (consisting of five branch lines, each with a baited hook) extending up to 80 miles. Day and night operations are common throughout the year, but seasonal variations in apparent abundance are reflected in changes in fishing effort. In the 1970s, deep longlines employing between 10 and 15 branch lines per basket were introduced. This new type of gear is theoretically capable of fishing down to a 300-meter (984-foot) depth, as compared to the usual 170 meters (557 feet) reached by traditional longline gear. Catch rates for T. obesus increased for about three years and then declined to previous levels again, suggesting that only a portion of the bigeye resources were exploited. Bigeye tuna is exploited in increasing quantities as associated catch of the spring and summer pole-and-line fishery in the northwestern Pacific, and of the purse-seine fishery in the eastern Pacific, both directed primarily at skipjack and yellowfin tuna. In Japan, its meat is highly priced and processed into sashimi in substitution for bluefin tuna. The catch reported for 1996 to the Food and Agriculture Organization of the United Nations (FAO) was 328,067 tons, of which 101,591 tons were taken by Japan, 64,498 tons by Taiwan, and 28,418 tons by Korea.
Bigeye tuna meat is reddish-pink in color, and, like yellowfin, it begins to discolor when exposed to air. For this reason, bigeye is usually not loined or filleted until shortly before use. Larger bigeyes typically have a higher fat content than the smaller ones, but even a fish as small as 25 to 30 pounds may be rich in fat. Bigeye tuna is one of the preferred species in the preparation of sashimi. With a high fat content, bigeye is also among the most desirable species for grilling. The Environmental Protection Agency (EPA) has issued a health advisory for longline-caught bigeye tuna because of high levels of mercury. The IUCN considers the bigeye tuna a “vulnerable” species.
Skipjack
The small skipjack tuna (Katsuwonus pelamis), also known as ocean bonito and striped tuna, is the most heavily-fished of all tuna and is one of the world’s most important food fishes. Skipjacks are found worldwide in tropical and subtropical waters, often aggregating in schools that may number as many as 50,000. In the Atlantic, they frequently associate with blackfin tuna (Thunnus atlanticus), and in the Pacific and Indian Oceans, they school with the yellowfin (Thunnus albacares). In the eastern tropical Pacific, all three species are fished by “setting on dolphins.” Skipjacks reach a length of 3 feet, but most are smaller. The world record-holder weighed 41 pounds and was caught off Mauritius in the Indian Ocean. In the Atlantic, skipjacks frequently associate with blackfin tuna (Thunnus atlanticus), and in the Pacific and Indian Oceans, they school with yellowfins (Thunnus albacares). The skipjack is a popular game fish, and it is the mainstay of California tuna fishery. It is of tremendous commercial importance in Japan, Hawaii, and the Caribbean, where it is marketed frozen, salted, and fresh. When canned, it is known as “light-meat” tuna.
Because yellowfin and skipjack aggregate, they are often caught together. Catches of both species are increasing. In 2002, the total catch of skipjack was 2,076,000 tons, amounting to 51% of the total tuna catch. Yellowfins amounted to another 32%, at 1,321,000 tons.11 In general, the outlook for world production of skipjack and yellowfin tuna is mixed. For yellowfin, most of the fisheries, with the possible exception of the eastern Indian Ocean, are probably fully exploited. For skipjack, catches can possibly be increased in the Pacific, but probably not much, if any, in the Atlantic and Indian Oceans. In the eastern Atlantic, the catches by the surface fleets targeting yellowfin and skipjack have reached the upper sustainable limit of yellowfin and probably are near that limit for skipjack. This tendency became obvious in the early 1980s and caused many purse-seine vessels from the Atlantic to transfer their operations to the western Indian Ocean (ICCAT, 1999).
The western Pacific supports the largest tuna fishery in the world, producing about 60% of the world’s skipjack and 35% of the world’s yellowfin. Analyses conducted by scientists of the SPC, based mostly on data from tagging experiments, suggest that the skipjack stocks of the region can support an increase in catch. However, for this increase to become reality, the stocks of currently underexploited skipjack must be identified, there must be a demand for the raw material, and they must be vulnerable to fishing gear. Increasing fishing effort may lead to increased catches of skipjack. However, in the western Pacific, as in the eastern Pacific, skipjack are often caught together with small yellowfin and bigeye. Therefore, the problem lies in ensuring that the increase is in catches of skipjack only, not those of yellowfin and bigeye.12
Almost 50 years ago, the NMFS built the world’s first research facility designed to maintain tunas in captivity at Kewalo Basin in Honolulu. Local fishers would bring in adult yellowtail and skipjack tuna, and they would be maintained in large tanks. Studies were conducted on visual acuity, sound sensitivity, olfaction, energetics, thermoregulation, geomagnetic sensitivity, and the spawning and rearing of tuna eggs. High-quality, coral-filtered seawater is used in several 20,000-gallon pools to hold tuna and other pelagic fishes. Skipjack captured at sea were installed in tanks at the Kewalo lab. They spawned about eight hours after capture, but the eggs did not survive.13
Commercial Tuna Fishing
Fishing with traps is perhaps the oldest known type of “commercial” fishing—that is, catching large numbers of fish to feed more than the fisherman and his family. The Phoenicians, who lived along the shores of the eastern Mediterranean some 30 centuries ago, are believed to have built traps that consisted of palm-tree branches stuck in the sand. They were used to guide the tuna into shallow water, where they were beaten to death with clubs or stabbed with spears (Sara, 1980). Almost completely enclosed by Europe and Asia Minor to the north and Africa to the south, the Mediterranean is open to the North Atlantic through the Straits of Gibraltar on the west and to the Black Sea by the narrow passage known as the Bosporus. The average depth of the Mediterranean is 4,900 feet, but extensive areas of the seafloor are below 6,800 feet. The deepest recorded point is 17,275 feet (about 3.27 miles) in the Hellenic Trough, west of the Peloponnesus. It is 2,400 miles from the Straits of Gibraltar to the shore of Lebanon, and the longest north-south distance (from Trieste to the shore of Libya) is about 1,000 miles. The Mediterranean’s 1.45 million square miles constitute the largest fish trap in the world; it was easy for the fish to get in, but very hard for them to get out.
For thousands of years, fish trappers have taken advantage of the enclosed nature of the Mediterranean. Improved and modified over time, the individual traps consist of a complex of nets that are held up by means of floats and are anchored to the bottom with weights. They form a series of one-way passages that funnel tuna into a final chamber, where they can be killed. Sara’s summary history of trap fishing in the Mediterranean identifies areas around Spain, the Balearic Islands, Corsica, Sardinia, Italy, Sicily, the Adriatic, Greece, and Turkey where trap fishing for tuna has been practiced for thousands of years. The surface circulation of the Mediterranean essentially runs counterclockwise. It moves eastward along the coast of North Africa, passing through the narrow Strait of Sicily and circling back in the northern quadrant, toward the Strait of Gibraltar and the open Atlantic. Because migrating tuna tend to swim close to the surface, they follow this circulation pattern until their journey is rudely interrupted by fishermen who lay traps for them. (By the 20th century, fishermen would catch fish off North Africa as well, but that is part of the tuna-farming story, which comes later.)
Tuna fishing was once one of Sicily’s most important and profitable industries. Until the first decades of the 20th century, coconut-fiber nets over a mile in length were deployed by the hundreds. But diminishing numbers of tuna and market laws that have made this fishing technique more capital-intensive have left only about ten tonnare (tuna fisheries) in the Mediterranean. Only Bonagia and Favignana are left in Sicily. What was once a source of pride (not to mention the primary source of income) for entire communities has turned into a tourist attraction. It provides a few makeshift jobs for the unemployed in a social context poor of prospects and is kept alive by the obstinate will of the remaining tonnaroti. The canneries in Sicily are closed; almost all the tuna caught in Favignana is shipped to Japan. Like everyone else, the Japanese fish buyers await the annual mattanza (tuna killing).
Other than the trap fishers, the earliest commercial fishers probably speared their prey, or worked from a canoe or dory with a baited hook on the end of a line. A variation of this method is employed today in tropical Pacific and Atlantic waters to catch the smaller tuna species, such as albacore and skipjack. Dories are not used. Instead, the fishermen stand at the rail of a fishing boat, attracting schools of tuna by “chumming,” and using bamboo poles with unbarbed, unbaited hooks. The tuna are yanked out of the water by the large crew of fishermen, thrown over their heads onto the deck, killed, and stored below decks in freezers. Some technically advanced countries have replaced the fishermen with “jigging machines” that perform the same function, thus decreasing labor costs.
The Greeks did not have a word for longlining, one of the most efficient of all fishing techniques. Longlining consists of a single line that may be 100 miles long (the distance from New York to Philadelphia), supported along its length by floats. The lines are hung with thousands of hooks baited with live or frozen baitfish and are deployed in an area where a particular species is being sought. Hanging from the longlines are as many as 3,000 hooks on “branch lines” that are dangled into the water and that can be adjusted to fish at depths ranging from 180 to 500 feet. It can take up to 8 hours to set the net and 12 to retrieve it. The gear is passive, in that it captures whatever fish happen to take the bait. The target species takes the bait, but so does every other kind of fish in the area. When tuna are the object of the fishery, sharks, billfishes, and any other fishes that are caught are often discarded, because it’s too much trouble to separate them. In 1995, an estimated 1,500 shy albatrosses (Diomeda cauta), out of a breeding population of 8,000, were caught in longlines and killed. Probably the most heinous use of longlines is in sub-Antarctic waters. Fishers of the Patagonian toothfish (Dissostichus eleginoides) scour the waters for their target species but kill hundreds of thousands of other fishes, whales, seals, dolphins, and as many as 150,000 seabirds annually. Longlining accounts for about 30% of the world catch, including most of the billfishes taken commercially. The largest longline fleets are those of Japan, followed by those of Taiwan, China, and South Korea.
When Japan developed monofilament fibers that could be used in open-ocean driftnetting in the mid-1970s, it introduced the most durable and destructive method of fishing ever devised. Large-scale, high-seas driftnets were first used in the North Pacific by fleets from Japan, Taiwan, and South Korea. Free from a connection with any boat, driftnets are set with floats at the top and weights at the bottom so that they drift passively in the water and trap anything that swims into them. Traditionally, these were small nets used in coastal waters to catch dense schooling fish such as herring. But with the introduction of light synthetic netting, driftnet fishing underwent a major change. The nets could now be used on the high seas, where they are very effective at catching wide-ranging species such as tuna and squid.
Early in fishery, big tuna were caught on hook and line, with chum being thrown in to excite the voracious fish into biting at anything and everything in the water. Fishermen stationed along the rails with heavy rods and unbaited, barbless hooks yanked the heavy fish over their shoulders, hoping to have them land on deck—which they often didn’t.
In the western North Atlantic, the purse seine and the longline changed tuna fishery so much that by 1964, the combined landings from these two fisheries had skyrocketed to 20,000 tons. As it became apparent that some sort of conservation measures were necessary to protect the great fish from overfishing, ICCAT was born. For control purposes, the Commission considered the Atlantic tuna as two stocks, separated by 45°W in the North Atlantic, with a dogleg around the bulge of South America to 25°W in the South Atlantic. Until the 1980s, most commercial tuna fishermen avoided taking the really big fish—bluefins can reach 1,500 pounds—because they were too difficult to handle. But when the Japanese sushi market opened its bottomless maw, the larger fish became the specific target of fishery. Prices skyrocketed, and it was almost impossible to convince people not to fish for tuna.
For more than two decades, ICCAT considered the biomass that existed in the mid-1970s to be the maximum sustainable yield (MSY) level for the western Atlantic bluefin tuna stock. But since 1975, the population has been allowed to decline by an additional 88%. According to ICCAT’s latest stock assessment, the biomass of this stock had declined to only 12% of that needed to produce the MSY. Thus, in just four decades, the population was driven from a healthy level (over three times the MSY level) to a level just above extinction. This occurred because of unrestrained fishing sanctioned by ICCAT on the world’s most valuable fish. The population is being held at this precarious level by continued overfishing allowed by ICCAT, ostensibly to provide scientific monitoring information on the bluefin’s status. In reality, it is unnecessary to kill any remaining bluefin until they can recover, because the abundance of each year’s class could be assessed using aircraft and other nonlethal means, such as tagging. But this would eliminate the large profits continuing to be made by a few fishers who have considerable political influence.
The tuna of the eastern zone, which are caught by Europeans, are managed under a strict annual quota set by the European Union. Those of the western Atlantic, targeted by American fishermen, have been managed under strict catch quotas since 1995. (Neither of these quotas includes farmed tuna.) Nevertheless, in both areas, the stocks of bluefin tuna have fallen dramatically: there has been an 80% decline in the eastern (European) stock over the past 20 years, and a 50% drop in the western Atlantic population.
Because of the prices they can fetch, bluefins have been overfished, and their North Atlantic breeding populations are estimated to have declined about 90% in the last 20 years. As with all fish populations, exact counts are impossible. Therefore, vast gaps exist between the high estimates, made (to no one’s surprise) by the fishermen, and the low estimates, made by those who would protect the tuna from overfishing. From dock to cabinet ministry, endless discussions have taken place at every level about solving the problem. But few protective measures have been taken, because doing so would require unprecedented domestic and international cooperation.
ICCAT is not based in Washington (its headquarters are in Madrid), but it might as well be. The commission is made up of 22 member countries on both sides of the Atlantic, plus Japan, which is, of course, a major fisher, importer, and consumer of Atlantic tuna. Under pressure from the powerful commercial fishing interests, ICCAT has consistently supported the fishers at the expense of the fish, while paying only the faintest lip service to recreational fishers. Even as the Atlantic tuna populations plummeted, and the fish were listed as endangered, ICCAT allowed the harvest of Thunnus thynnus at levels that endangered the species even further.
ICCAT’s charter explicitly states that tuna stocks should be managed for maximum sustainable yield (MSY). This approach seeks to maximize the annual harvest by holding the population at approximately 50% of the predetermined environmental carrying capacity. At this level, the population should reproduce at its maximum rate so that the recruitment of new fish to the population is maximized each year. As long as the population is not reduced below the MSY level, the theory goes, fishermen can harvest the annual surplus indefinitely. But bluefin tuna populations rise and fall for a variety of environmental reasons, and trying to factor in the MSY only contributes to the chaotic nature of the population assessments. Because the MSY may never be determined with any sort of accuracy, quotas can swing wildly from year to year and impact the population in ways that fishery biologists do not yet understand. ICCAT began keeping records in 1976. But, as Myers and Worm pointed out in 2003, over the past 50 years, Japanese and other longline fleets around the world have reduced the populations of large predatory fishes (sharks, tuna, billfishes) by 90%, leaving the remaining 10% for today’s fishers. Add to that ICCAT’s dedication to maximizing the total allowable catch (TAC) for all commercial tuna fishers, no matter where they are based or where they fish, and you can begin to understand why North Atlantic tuna populations are at an all-time low. And why Japanese consumption of bluefin tuna is at an all-time high. Low population added to intensified fishing effort only leads to disaster, as is happening in the Mediterranean.
Obviously, a robust population requires the addition of new animals, which means that the spawning stocks of the tuna must be protected—or at least not killed off. ICCAT failed to protect the spawning stocks of Atlantic bluefin for many years, and population levels have fallen far below the level required to sustain MSY. Between 1970 and 1993, the recruitment of young fish into the adult population fell from over 300,000 per year to only 50,000 or fewer (Safina, 1993). In 1975, stock size estimates for spawning fishes (those over 320 pounds or 145 kg) were at only 25% of levels estimated in 1960. By 1990, spawning stock was at only 7% of the 1960 level. Furthermore, ICCAT still operates under the assumption that there are two distinct stocks of northern Atlantic bluefin: one that spawns in the Gulf of Mexico and migrates north along the coast of North America, and another stock that spawns in the Mediterranean and migrates along coastal Europe and northern Africa. The western stock has declined precipitously over recent decades, and the catch from the western stock is highly regulated by ICCAT and the U.S. National Marine Fisheries Service (see Figure 4.4).
Figure 4.4. Atlantic bluefin tuna stock size
Source: Tag-A-Giant
Tagging studies confirmed that some subadults or adults hatched in the Gulf of Mexico found their way to the Mediterranean, but tag returns were very limited. Eastern fishermen tend not to report the capture of tagged western fish in the Mediterranean because they fear it would cause the imposition of restrictive quotas. Even today, European ICCAT representatives are reluctant to redefine bluefin stock structure because they don’t want to consider restrictive quotas on eastern fishermen. This reluctance, coupled with the introduction of tuna ranches in the Mediterranean, have resulted in such a massive crash of the eastern Atlantic and Mediterranean bluefin tuna populations that the WWF has called for an immediate closure of all Mediterranean tuna fisheries.14
By 1987, the Japanese squid fleet had expanded to 1,200 boats, each deploying up to 30 miles of nets every night during a seven-month fishing season. Some of the nets were 40 miles long. Japanese and Taiwanese boats driftnetting for albacore kill not only the tuna, but tens of thousands of other animals as well. In 1989, conservationist guerilla Sam La Budde made a film called Stripmining the Seas, which showed driftnets being hauled aboard and drowned dolphins being kicked overboard. The film was seen by many people, including members of the U.S. Congress. Objections to driftnetting kept piling up. In 1989, the United Nations adopted a resolution to reduce driftnet fleets and ban driftnetting in the South Pacific. Japan and Taiwan were the major culprits. A 1989 report showed that the Japanese squid fleet alone was responsible for the death of a million blue sharks, 240,000 seabirds, and 22,000 dolphins. Over worldwide objections, the Taiwanese continued to deploy their “curtains of death,” and they are still being used by pirate driftnetters. A net that has been cut loose or has broken loose does not quit working. It keeps killing fishes, dolphins, and sea turtles even when there is no one to haul in the net to harvest or release the prisoners. Known as “ghost nets,” these gigantic net walls keep on fishing long after the mother ship has departed.
The Mediterranean has been the scene of intense driftnet fishing, even though it supposedly has been outlawed. Prohibitions have had little effect, however, and driftnets are still being set by the fishers of various Mediterranean countries, particularly Greece and Italy. In the summer of 2006, two conservation organizations, Greenpeace and Oceana, deployed vessels to document and film the illegal driftnetters at work. The Greenpeace flagship Rainbow Warrior spent three weeks confronting (and filming) rogue fishing boats in the Mediterranean. Sofia Tsenikili of Greenpeace Greece said, “If people are horrified by the images of whales being harpooned in the Southern Ocean, they’d be equally repulsed by the thousands of dolphins and other creatures that are being entangled and killed by fishermen using huge illegal driftnets each season in the Mediterranean.” Oceana, a network of marine conservationists, has also documented the use of illegal driftnets by Italian fishers in the Mediterranean. The Oceana Ranger sailed through 1,500 miles of the Ligurian and Tyrrhenian Seas, observing numerous vessels “capturing species like swordfish or albacore tuna with driftnets that are totally banned. We have also witnessed how these catches are unloaded in ports without any type of control...and after being loaded into trucks, they are ‘laundered’ through irregular supply chains.” The illegal fishers were reported to the Italian Coast Guard, but it is unlikely that anyone can stop driftnetting—it is just too lucrative.
When the stocks of western North Atlantic codfish crashed 10 years ago, fishing for cod was banned to allow them to recover. But as reported by Bundy et al. in 2000, the population dynamics have been so drastically altered that cod may never reappear in their former numbers. Not only cod, but also virtually all high-quality table fish, such as tuna, haddock, and flounder, have fallen to about 16% of what their numbers were in 1990.
Endnotes
1 Hori, T. 1996. Tuna and the Japanese. Japan External Trade Organization.
2 Brill, R.W. and P.G. Bushnell. 2001. The cardiovascular system of tunas. In B.A. Block and E.D. Stevens, eds. Tuna: Physiology, Ecology, and Evolution. 79-120. Academic Press.
3 Fromentin, J.M. and J.E. Powers. 2005. Atlantic bluefin tuna: population dynamics, ecology, fisheries and management. Fish and Fisheries 6(4):281-298.
4 Bigelow, H.B. and W.C. Schroeder. 1953. Fishes of the Gulf of Maine. U.S. Fish Wildl. Serv. Fish. Bull. 74:1-577.
5 Seabrook, J. 1994. Death of a giant: stalking the disappearing bluefin tuna. Harper’s 288(1729):48-56.
6 Hayes, E.A. 1997. A Review of the Southern Bluefin Tuna Fishery: Implications for Ecologically Sustainable Management. TRAFFIC Oceania.
7 Schaefer, K.M. 2001. Reproductive biology of tunas. In B.A. Block and E.D. Stevens, eds. Tuna: Physiology, Ecology, and Evolution. 225-270. Academic Press.
8 Reid, T.R. 1995. Tsukiji: The great Tokyo fish market. National Geographic 188(5):38-55.
9 Smith, T.D., ed. 1979. Report of the status of porpoise stocks workshop (August 27-31, 1979, La Jolla, California). NMFS Southwest Fisheries Center Administrative Report LJ-79-41. 62.
10 Preston, G.L., L.B. Chapman, and P.G. Watt. 1998. Vertical Longlining and Other Methods of Fishing Around Fish Aggregating Devices (FADs): A Manual for Fishermen. Secretariat of the Pacific Commission.
11 de Leiva, J.I. and J. Majkowski. 2005. Tuna resources. FAO. Rome.
12 Hampton, J., A. Lewis and P. Williams. 2002. The Western and Central Pacific Tuna Fishery: 2000 Overview and Status of Stocks. Tuna Fisheries Assessment Report/Secretariat of the Pacific Community. Oceanic Fisheries Programme Report No. 3:59.
13 Schaefer, K.M. 2001. Reproductive biology of tunas. In B.A. Block and E.D. Stevens, eds. Tuna: Physiology, Ecology, and Evolution. 225-270. Academic Press.
14 Bregazzi, R.M. 2006. The Plunder of Bluefin Tuna in the Mediterranean and East Atlantic in 2004 and 2005: Uncovering the Real Story. World Wide Fund for Nature.