Species contact: Gregory Skomal
Scientific name: Thunnus thynnus
Common names: Bluefin tuna, horse mackerel, Atlantic bluefin tuna, bluefin tunny, northern bluefin tuna, squid hound, toro, giant bluefin
Size: Exceed 10 feet in length and weights over 1,000 pounds, making them among the largest bony fish in the world. However, most are commonly see at 78 inches. One-year-old tuna are about 10 pounds and age 2-4 bluefin tuna are typically 20-80 pounds. 'Giant' is a subjective term used for mature bluefin tuna that typically are at least 10 years old and 200 pounds or more.
Color: Deep metallic blue dorsally - although on larger fish this can appear black - fading down the sides to silver with a silvery-white belly. Sometimes irregular iridescent white, grey, and silver bands and spots are on the belly. The first dorsal fin is yellow or blue while the second dorsal fin is red or brown. The anal fin and finlets are yellow and edged in black.
Body: Like all tunas, the body is fusiform, making the fish look something like a giant football. The body is tallest behind the operculum and where the pelvic fins begin. The body then tapers to the caudal peduncle. This tuna has a pointed snout and smaller eyes than other tuna species. Like most other tunas and pelagic bony fish, the dorsal, pelvic, and pectoral fins fit into slots in the body to reduce drag while cruising in the water.
Bluefin tuna are similar in bodystyle to other tuna species, but is most commonly confused with yellowfin tuna (Thunnus albacores), especially when young.
Prey: Pelagic schooling species like mackerel, sand lance, sea herring, and squid. When there are no schooling species, bluefin tuna will feed on whatever they encounter in the water column. Nearshore bluefin tuna have been recorded to eat sea stars, kelp, and shallow water fish.
Predators: Seabirds and larger predatory fish feed on juvenile bluefin tuna. As adults, they are targeted by sharks and some marine mammals, including killer whales and pilot whales.
Despite the popularity as a prized sport fish and as a coveted sushi fish, little is known about the life history of bluefin tuna. Spawning has been detected in only two areas of the Atlantic: the Mediterranean (June to August) and the Gulf of Mexico (April to June), but never seen.
What is known about bluefin tuna mainly comes from captivity. Those in human care have reached maturity at three years. Western Atlantic stocks mature later, at around age eight. An average female produces up to 10 million eggs per year while it is estimated that giant females can release over 25 million eggs per year. The eggs are buoyant and travel great distances on currents. Larvae hatch at roughly 0.11 inches. The head and jaw are large and the body is transparent. Larvae grow roughly 0.039 inches per day. Between 90 and 130 pounds, bluefin tuna separate into schools based upon size. The smaller the individual size, the larger the school, and vice versa. Many times, these schools comprise multiple species including albacore, yellowfin, bigeye, bonito, and skipjack tunas.
Pelagic, a highly migratory species. They are obligatory ram ventilators, meaning they must continually move in order to pump oxygenated water over their gills. Bluefin tuna will come close to shore seasonally and have been observed at various depths within the water column from the surface to greater than 3,000 feet below the surface.
Bluefin tuna are a world-wide species in subtropic and temperate waters. In the western Atlantic Ocean, bluefin tuna are found from Labrador, Canada southwater to northern Brazil, including the Gulf of Mexico. Tagged bluefin tuna have been tracked crossing the Atlantic in less than 60 days.
Harvest of bluefin tuna in the western Atlantic has occurred for less than 100 years, unlike the rich history found in the eastern Atlantic and Mediterranean Sea. Bluefin tuna were not an important target species on the East Coast of the United States during the first half of the 20th century. Most commercial landings came from handgear catches in Maine and trap net catches in Massachusetts. The latter half of the 20th century saw major technical changes to bluefin tuna fisheries that resulted in stock reductions and prompted extensive management measures. Three major developments have had the greatest impact on bluefin tuna in the Atlantic: development of purse seine fishing in the late 1950s, development of high-seas longlining by the Japanese in the late 1950s, and the opening of the high-price Japanese sashimi market in the 1970s.
Massachusetts has been the top state for commercial landings nearly every year since the late 1940s. The port of Gloucester has been the top handgear port for bluefin tuna on the East Coast during most for the last 50 years and recently Harwich has taken the lead on the graces of high catch rates in the Great South Channel.
U.S. fishermen harvest bluefin tuna using rod and reel, harpoon, handline, and purse seines. Targeting schools of tuna - which may contain other, unwanted species - with these selective gear allow for live release of the unintentionally caught species. Commercial fishermen are not allowed to use pelagic longlines to target bluefin tuna. However, strict regulations allow for a limited number of incidentally caught bluefin tuna to be kept.
NOAA Fisheries based on the International Commission for the Conservation of Atlantic Tunas. Click on the links for more information or call 1-888-USA-TUNA. Appropriate permits (commercial or recreational) must be purchased from NOAA Fisheries before targeting and harvesting bluefin tuna. Like commercially harvested tuna, recreationally harvested bluefin tuna must be reported.
Bluefin tuna are one of the most prized sport fish to target. Many anglers are excited by catching any size bluefin tuna, however enthusiasts target giants every summer. To catch a giant bluefin tuna, use a sturdy rod with a large, high quality reel. Use high test line to avoid snapping as the fish takes a run.
The two primary methods for catching bluefin tuna are trolling with rigged natural baits or artificial squids on spreader bars and bait fishing on anchor with live bait or chunks of local prey such as herring or mackerel. The way a bluefin tuna fights is highly variable between individuals and there are numerous ways to lose a hooked fish. therefore, catch rates are typically low. However, anglers continue to show enthusiasm.
Smaller bluefin tuna are fished in similar patterns as giants, with the exceptions of downsizing the gear. anglers south of Cape Cod often increase the troll speed and use a variety of brightly colored, single hook lures to attract schooling tuna.
If you are harvesting a bluefin tuna, take care to bleed and chill the fish quickly. Life the pectoral fins on both sides and make a one inch incision to cut the cutaneous veins and arteries that run along the lateral line. Quickly and carefully gut the fish soon after capture.
Bluefin tuna is a highly valuable fish. They are known in sushi and as tuna steaks. the meat is dark red and firm. it is also the fattiest of any tuna species.
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