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Home , Dogtooth tuna, Euthynnus lineatus, Frigate tuna

ÜBER-FISH Among the World’s Most Popular Game Fishes, Are Also Some of the Most Highly Evolved and Sophisticated of All the Ocean’s Predators

BY DOUG OLANDER DANIEL GOEZ DANIEL

74 DECEMBER 2017 SPORTFISHINGMAG.COM 75 The Family Tree minimizes drag with a very low reduce the turbulence in the Tunas are part of the family drag coefficient,” optimizing effi- water ahead of the tail. , which also includes cient swimming both at cruise Unlike most fishes with broad, mackerels, large and small. But and burst. While most fishes bend flexible tails that bend to scoop there are tunas, and then there their bodies side to side when water to move a fish forward, are, well, “true tunas.” moving forward, tunas’ bodies tunas derive tremendous That is, two groups don’t bend. They’re essentially­ thrust with thin, hard, lunate WHILE MOST FISHES BEND (sometimes­ known as “tribes”) rigid, solid torpedoes. (crescent-moon-shaped)­ tails dominate the clan. One is And these torpedoes are that beat constantly, capable of THEIR BODIES SIDE TO SIDE Thunnini, which is the group perfectly streamlined, their 10 to 12 or more beats per second. considered true tunas, charac- larger fins fitting perfectly into That relentless thrust accounts WHEN MOVING FORWARD, terized by two separate dorsal grooves so no part of these fins for the unstoppable runs that fins and a relatively thick body. a number of highly specialized­ protrudes above the body surface. tuna make repeatedly when TUNAS’ BODIES DON’T BEND. The 15 of Thunnini are features facilitate these They lack the convex eyes of hooked. Anyone who has gaffed , bigeye, black skipjack, swimming­ machines. most fish; rather, a membrane a tuna, large or small, will recog- blackfin, bluefin (three species: Of their fusiform body covering tuna eyes remains flush nize the staccato rat-a-tat-tat its THEY’RE ESSENTIALLY­ RIGID, Atlantic, Pacific, southern), shape (tapering fore and aft), with their heads, maintaining a tail continues to beat out on deck bullet, frigate, kawakawa, little Sport Fishing Fish Facts expert surface with minimal drag. after its capture, as even then it SOLID TORPEDOES. tunny, longtail, skipjack, slender Ben Diggles says, “Their almost Keels and finlets in front of keeps on “swimming,” because,

and yellowfin. perfect hydrodynamic shape (BOTTOM) LANDON COHEN (TOP), STEMPLE JASON the tail provide stability and help (Continued on page 81) The other tribe is Sardini; these tunas — the and several species of smaller true — are somewhat Above: The similarity of more mackerel-like (notably, this small tuna with a more elongated body and a to a model That the ocean’s most advanced row of sharp, conical teeth). airplane is no accident. Both and highly developed swimming bear similarities Swimming Machines in streamlined machines are also among the most Sport fishermen know that when design for they hook a large tuna, they’re in efficient, rapid popular of game fishes with the for a long, drawn-out, ­relentless forward motion. battle. Nothing characterizes Right: The world’s saltwater angling enthu- king of tunas, tunas more than their powerful, Atlantic bluefin siasts is hardly a coincidence. tireless swimming. In fact, these may range from fish have no choice but to swim “small giants” As anglers, we have ­tremendous endlessly: As explained more like this one to at least 1,500 respect for the spirited fighting thoroughly below, they’re ram pounds. ventilators, meaning forward qualities of tunas — difficult to motion is required as they move release, should we wish to, because with mouth open to force water past their gills. they truly will fight their hearts Most fishes, such as ,­ snappers and jacks, can remain out when hooked. So what is it motionless and respire by that makes tunas the über-fish of opening and closing their mouths to push water through their gills. our oceans? The more we learn Tunas have lost the ability to do that (even if they could, such about our favorite , small pushes of water wouldn’t the more fascinating they are. offer their large gills the tremen- dous flow they require to supply their systems with oxygen). A suitable motto for tunas, then, is “swim or die.” How tunas have evolved to move efficiently through the water is reflected in their design, both externally and internally. As the illustration (page 81) shows,

76 DECEMBER 2017 SPORTFISHINGMAG.COM 77 The Tuna Tribe

A B G H I C

D E F J K L

(A) ALBACORE or streaked); the yellowfin’s is as live bait for billfish and large three species of bluefin (Atlantic, (along with true bonitos — basically 36 pounds — Washington Canyon, (K) SKIPJACK at times. The fast-growing tuna ( alalunga) not. Found worldwide, this prized yellowfin. The strong dark-red flesh Pacific and southern) tolerate a smaller versions) belong in a New Jersey, 2006 (Katsuwonus pelamis) can reach 200 pounds in seven game fish is also an important is not appealing to most fishermen. great range of temperatures and different group from bluefin, A fish of many names, years. Anglers in eastern Pacific IGFA all-tackle record: IGFA all-tackle record: 88 pounds, target for commercial longliners. migrate great distances, across yellowfin and relatives isn’t hard are known as false albacore waters take advantage of the 2 ounces — Canary Islands, 1977 (E) BLUEFIN 45 pounds, 4 ounces — Baja both oceans. Satellite tags have to imagine. Unlike those true off the U.S. Northeast and mid- yellowfin symbiotically feeding (C) BLACKFIN (Thunnus thynnus) California, Mexico, 1996 Easily identified, having by far revealed transatlantic crossings in tunas, dogtooth are longer, leaner Atlantic states, where they’re a with dolphin (porpoise). From (Thunnus atlanticus) With distinct horizontal stripes the longest pectoral fins of any IGFA all-tackle record: 1,496 pounds less than 60 days. Decades ago, and maybe even meaner. Per its very popular game fish among years spent as an observer for limited to its lower half (and no tuna, albacore are also noted for IGFA all-tackle record: — Nova Scotia, Canada, 1979 giants made a reliable migration name, check out its dentures, light-tackle and fly anglers. In the Inter-American Tropical the lightest, whitest flesh among stripes dorsally), the skipjack 49 pounds, 6 ounces — The king of tunas, giant bluefin each May off Bimini and down the most impressive of any tuna. Also, the Southeast and Gulf, they’re Tuna Commission, California tunas. Circumglobal, albacore Marathon, Florida Keys, 2006 is readily distinguished from are for many anglers the ultimate Florida Strait, but that suddenly dogtooth are far more solitary, mislabeled , and generally photographer, writer and angler prefer temperate (versus tropical) other small tunas. One of the Blackfin are also similar in prize among all game fishes. Ditto came to an end after the 1960s. and unlike most tunas are not a avoided. Yet they are tremendous Bill Boyce says tuna definitely most widely dispersed of small seas and rarely venture near shore. appearance to small yellowfin, schooling species. Finally, they fighters for their size, battling in follow dolphin (not vice versa). for sushi eaters, who at market (F) BONITOS They’ve long been a popular prefer to haunt steep reef slopes; classic tuna fashion. Little tunny are tunas, the skipjack is found The tuna seem to understand that but the blackfin’s finlets are dark may bid hundreds of thousands of (Sarda spp) target for California anglers, in all temperate and tropical rather than bright yellow. The dollars for a single giant. (In 2013, anglers needn’t travel far offshore readily identified by the wavy lines dolphin will find the baitfish; the particularly off the central part of seas, where it often forms huge species is limited to the western a Japanese businessman coughed IGFA all-tackle records: Atlantic — to tangle with doggies. A fine along their upper back, behind tuna then help corral the bait, the state, but their availability schools. Not all anglers realize Atlantic, most commonly from up $1.76 million for a 488-pound 18 pounds, 4 ounces, Azores, 1953; eating fish, dogtooth are known for the dorsal, and the spots between pushing it to the surface. in the summer varies greatly from Pacific — 21 pounds, 5 ounces, that its light meat should make the mid-Atlantic states south to bluefin during a bidding war in their brutal power when hooked. pectoral and ventral fins. Small year to year. Later in summer and Southern California, 2003 it a preferred species for the OTHER TUNAS Brazil, including the Gulf of Mexico. Tokyo’s first auction of that year.) (H) KAWAKAWA tunny are also popular as baitfish, fall, albacore move up into waters In addition to the Atlantic bonito, fish box. The skipjack is of Blackfin often form large schools, There’s some irony in the fact that ( affinis) drifted live or trolled dead. They There are several other species off Oregon, Washington and huge importance globally as a sometimes mixed with little tunny, before the latter part of the 20th there are three other species form and feed in tight schools, of very small tuna, generally British Columbia but are often too commercial species, with great around offshore structure and reef century, sport fishermen had no of Sarda (Pacific, striped and IGFA all-tackle record: 33 pounds, often churning the surface as they not commonly caught or of less far offshore for most. 3 ounces — , 2014 tonnage ending up canned. drop-offs. They’re an important and use for giant bluefin, which at Australian). These four true bonitos gorge on baitfish. The dark-red, interest to anglers. These include are related to dogtooth tuna and popular sport fish for the South best were reduced for pet food, Known as mackerel tuna in bloody meat of little tunny keeps (L) YELLOWFIN the little ( rochei), (B) BIGEYE share that species’ shape — more Atlantic and Gulf states. being considered unpalatable. , the kawakawa — native them out of fish boxes. (Thunnus albacares) (Auxis thazard) and (Thunnus obesus) elongated than other “true” tunas BLACK SKIPJACK Go figure. Bluefin mature at to the Indo- and western Pacific LONGTAIL slender tuna (Allothunnus fallai), (D) — and somewhat non-tuna-like (J) IGFA all-tackle record: 427 pounds — IGFA all-tackle records: Atlantic — about six years of age, around — is similar to the little tunny of the latter found in cooler waters of () () Cabo San Lucas, Mexico, 2012 392 pounds, 6 ounces, Canary 300 pounds. Atlantic bluefin spawn sharp-toothed dentition. All are Atlantic waters. It is also a dark- southern oceans (one was caught Islands, 1996; Pacific — 435 pounds, IGFA all-tackle record: 26 pounds — in the Mediterranean and Gulf small coastal pelagics; all make meat species, though popular IGFA all-tackle record: 79 pounds Named for its bright-yellow in Los Angeles Harbor, though as Cabo Blanco, Peru, 1957 Baja California, Mexico, 1991 of Mexico, and are now believed outstanding light-tackle game among many anglers for food, as 2 ounces — New South Wales, finlets, the yellowfin is pelagic-fish expert John Graves, Australia, 1982 Bigeye may be confused with This species is one of the few tunas — per the research of scientist fish and (even if not universally in Hawaii. Kawakawa are, typically, fantastically popular among of the Virginia Institute of Marine yellowfin, but their yellow finlets limited to the eastern Pacific, found Molly Lutcavage — to spawn appreciated) fine table fare as tremendous fighters for their size. The longtail inhabits the Indo- anglers who fish tropical seas Science, speculates, it was likely are edged in black and their eyes in waters off California to Peru. in the western Atlantic as well. sashimi or cooked. Kawakawa mostly inhabit coastal Pacific, quite near shore, even around the world. Their habit dumped from the baitwell of a may indeed be a bit larger. The The black skippy can be identified They’re not terribly picky eaters, (G) DOGTOOTH reefs and may even move into prowling estuaries and river of schooling and feeding at boat returning to port). bigeye may also be more robust in by the four or five broad, straight devouring even very small baitfish, (Gymnosarda unicolor) estuaries. mouths, where it often roams in the surface makes yellowfin its body shape. But the single sure stripes that extend horizontally and invertebrates, including large shoals. A popular game fish particularly exciting targets for (I) LITTLE TUNNY way to distinguish the two species IGFA all-tackle record: 236 pounds, among Australians, the species run-’n-gunners. Yellowfin are along its back. A hard-hitting, fast- starfish, have shown up in stomach (Euthynnus alletteratus) is underneath the skin: The moving predator, smaller skipjack analyses. Bluefin range from far 15 ounces — Tanzania, 2015 is there labeled northern bluefin, decidedly bluewater pelagics bigeye’s liver is striated (striped are popular among anglers for use offshore to near-coastal waters. The That the Indo-Pacific dogtooth IGFA all-tackle record: though it is not a species of bluefin. but may move into coastal waters ILLUSTRATIONS: DIANE PEEBLES ILLUSTRATIONS:

78 DECEMBER 2017 SPORTFISHINGMAG.COM 79 A Swimming Machine (C) FINS FOLD FLUSH (B) CORSELET (E) LUNATE TAIL

(A) EYES (D) FINLETS

(F) HEATED BODY (H) MEGA-GILLS

(G) EXTENDED PECTORAL FINS

(A) EYES: Flush with body; no protrusion to cause additional turbulence. (B) CORSELET: A patch of specially modified (larger, thicker, hollow) scales just behind the head of large tunas may break up turbulence around the widest part of the body to reduce drag when swimming and may also help heat conservation. (C) FINS FOLD FLUSH: Dorsal and pectoral fins fit perfectly into grooves so no part of them protrudes to avoid any extra drag, but they can be extended when needed for greater maneuverability. (D) FINLETS: Create slight turbulence to create a smoother path for the tail. (E) LUNATE TAIL: A rigid design that maximizes thrust and efficiency. (F) HEATED BODY: Larger tunas are warmblooded; vascular heat exchangers that maintain temperatures in selected body regions higher than surrounding water offer many advantages, including stabilizing body temps and warming the cool blood coming from the gills when cruising (but when chasing prey or fighting an angler, working in reverse to dissipate heat to surrounding water to prevent overheating). (G) EXTENDED PECTORAL FINS: Act as lifting hydrofoils (compensating during their ceaseless forward motion for lack of a ). (H) MEGA-GILLS: Roughly 10 times larger than gills of most (ectothermic, or coldblooded) fishes, these meet huge, incessant demands for oxygen.

well, that is what tunas do. muscle. Many fishes are ambush oxygenated blood through their As with other fast-swimming ­predators, relying on bursts bodies requires tunas to have far fishes, a primary limitation on of speed to feed but swimming larger hearts than most fish. Not top speed for tunas is cavita- slowly otherwise. Their bodies are only that, but another way tunas tion, which at high speeds can mostly filled with white muscle have advanced beyond most slow them and even damage — glycolytic fibers used in infre- fishes — which have a constant fins. (Cavitation is caused when quent burst swimming. Tunas heart rate — is their ability, like negative pressure forms tiny air employ far more red muscle; their mammals, to vary their heart Unlike the white bubbles, which then collapse and oxidative fibers prove ideal for rate, maximizing efficiency. meat of often motionless form shock waves. Just as cavi- long-haul, constant swimming ambush tation can damage the metal in without fatigue. Also, red muscle Hotblooded predators such propellers, it can cause lesions is full of myoglobin, which stores Arguably the most striking and as , in the fins of fish that swim “too oxygen in the muscle tissues, for sophisticated adaptation we can’t the red-pink muscle of tuna fast,” such as tunas.) use as needed. see — but science has revealed — is designed for With so much red muscle is the ability of larger true tunas tireless, long- Landing a giant Under the Hood demanding that much more to heat certain areas of their haul swimming. bluefin off While many of the ­characteristics oxygen, tunas’ gills — their bodies. They do this through what Nova Scotia that account for the tuna’s organs for respiration, of course are known as the retia mirabilia during one of the International Tuna remarkable swimming ability — are huge. For example, a tuna (“wonderful net”), an ingenious Cup Matches circa are visible externally, some of has seven to nine times more gill counter-current vascular heat- the 1950s. the most astonishing adaptations area for its size compared to rela- exchange system. Basically, are internal. tively sedentary trout. And, not parallel veins and arteries Certainly, that includes surprisingly, you’ve gotta have exchange blood, allowing tunas to

ILLUSTRATION: KEVIN HAND; PHOTOS: © SCOTT KERRIGAN / WWW.AQUAPAPARAZZI.COM (BOTTOM RIGHT), COURTESY IGFA / IGFA.ORG (OPPOSITE) / IGFA.ORG IGFA COURTESY RIGHT), (BOTTOM WWW.AQUAPAPARAZZI.COM KERRIGAN / © SCOTT KEVIN HAND; PHOTOS: ILLUSTRATION: their extensive aerobic red heart: Moving great amounts of conserve metabolic heat via what

80 DECEMBER 2017 SPORTFISHINGMAG.COM 81 is called regional endothermy, Diving Deep, warming their red muscle tissue, Wandering Wide brain, eyes and viscera well above Much of the evolutionary success ambient water temperatures. of tunas derives from their ability This gives them the same to transition from warm to cool metabolic advantage that waters in a way that most — less Homo sapiens and other advanced, coldblooded — fishes mammals enjoy. In fact, tunas can’t manage. Top: The couldn’t sustain the swim-or-die Satellite tagging has revealed astounding annual run of lifestyle nor be the relentless much about the feeding behavior giant bluefin eating machines they are without and movements of large tunas, off Bimini every that higher metabolic rate, including their tendency to dive year into the allowing them to swim longer into deep, cold water. Scientists 1960s thrilled anglers to see and faster, their brains and eyes have documented that yellowfin (and hook) such to function better in cold water, feed at times in waters much huge fish in the and their viscera to digest more deeper than once believed, but clear shallows. quickly and efficiently. the bigeye is a champ in the deep- feed during the day. Perhaps not at depth, but rewarming occurs South Pacific, the largest giants Above: Few fish Further demonstrating the dive category, often feeding in so surprisingly, daytime swordy when tunas move up into warmer come from the most southern better suggest the proverbial brilliance of their plumbing, waters exceeding 1,500 feet — and anglers have been hooking some waters — where heating occurs at part of the southern bluefin’s junkyard larger tunas can shed excess heat diving to more than 5,000 feet. large tuna while dropping deep. 100 to 1,000 times the rate that range — off New Zealand’s South dog than the from their bodies during periods Apparently, these daytime The other abyss-loving tuna is it’s lost. (This may be facilitated Island. In both instances, only dogtooth tuna. of intense feeding (in essence, deep divers are taking advantage the bluefin. What large yellowfin, with blood bypassing lateral heat the great body mass of giants Right: While while doing wind sprints) via their of what’s known as the deep- bigeye and bluefin have in exchangers, so blood warmed provides enough thermal inertia they don’t jump LARGE TUNAS ARE TRULY when hooked, retia mirabilia, which use blood scattering layer, a concentration common that enables them to and oxygenated in the gills by — a small enough ratio of surface yellowfin from gills cooled by ambient of biomass (plankton and larger feed at great depths is body mass. ambient, warmer waters enters area to volume to prevent rapid often launch water to reduce body heat. This organisms) typically settling by Juveniles and smaller species of the red muscle directly.) cooling — so they can take ­SUPERFISH, AT THE repeatedly when system also undoubtedly comes day into 1,500 to 2,000 feet of tuna, lacking that, lose body heat What large tunas have in ­advantage of vast schools of prey. chasing baitfish. into play as one factor in the water (which rises to or near too rapidly to allow them to leave common that encourages them Large tunas are truly ZENITH OF EVOLUTIONARY amazing endurance that hooked the surface nightly). This is the near-surface waters for long. to feed so deep is simply an abun- ­superfish, at the zenith of evolu- tunas show to resist their capture. same DSL in which swordfish Heat is lost in the frigid waters dance of food in these cold but tionary design and success as DESIGN AND SUCCESS AS productive waters. predators among the ocean’s The same holds true for fishes. Little wonder they’re ­horizontal movements as well among the very most popular PREDATORS AMONG THE Is Disaster Imminent for Tunas? as vertical dives into colder targets worldwide among salt- Tunas occasionally make it into mainstream news, and when they do, the circumstances (for continued survival of the species) usually sound pretty waters. So, for example, in the water recreational fishermen. OCEAN’S FISHES. dire. However, a scientist at the University of Washington, on cfooduw.org, found that, at least through 2014 (per available data), only eight of 22 North Atlantic, the world’s The more we as anglers under- commercial tuna stocks had an abundance below that which would produce maximum sustainable yield. Two stocks, says Ph.D. candidate Maite Pons largest giant bluefin are caught stand these magnificent fish, — Pacific bluefin and bigeye in the western central Pacific — are fished hard enough to threaten their collapse. But that’s two of 22. She concludes by at the most northerly edges the more we can appreciate the saying, “The abundance of tunas and their relatives has declined from preindustrial levels, but in general, they are at sustainable levels,” with a few of the species’ range — the opportunity to fish for and noted exceptions (and some showing signs of rebuilding at this time). (RIGHT) HAYDAHL JESSICA LEFT), GRANVILLE (ABOVE DAVID LEFT), (TOP / IGFA.ORG IGFA COURTESY Canadian Maritimes — and in the catch them.

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