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A Guide to the Tunas of the
Western Atlantic
BLUEFIN TUNA
THUNNUS THYNNUS
Distinctive Characteristics Bluefin have a fusiform body,
compressed and stocky in front. The pectoral fin does not reach the origin
of the 2nd dorsal fin. The height of the 2nd dorsal fin is greater than
that of the 1st dorsal fin.
The liver is striated on the ventral surface, and a swimbladder
is present. There are 34-43 gill rakers on the first gill arch. The back
and upper sides are dark blue to black with gray or green iridesence.
The lower sides are silvery, marked with gray spots and bands. The 2nd
dorsal fin is reddish-brown, and the anal fin is dusky with some yellow.
The finlets are yellow, edged with black. The caudal keel is black at
the adult stage, but is semitransparent when immature.
Size
Maximum: over 118 inches
Common: 16 to 79 inches
Current IGFA all tackle record 1,496 pounds.
Distribution and Behavior
Bluefin are widely distributed throughout the Atlantic.
They are found in the western Atlantic along Labrador and Newfoundland,
southward to Tobago, Trinidad, Venezuela, and the Brazilian coast. Distribution
in east Atlantic extends as far north as Norway and Iceland, and as far
south as northern West Africa. Also exists in the Mediterranean Sea.
Western Atlantic bluefin tuna are sexually mature at approximately
age 8 (80 inches Curved Fork Length). Eastern Atlantic bluefin tuna spawn
in the Gulf of Mexico (April-June) and in the Mediterranean Sea (June-July).
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YELLOWFIN TUNA
Thunnus albacares
Distinctive Characteristics Fusiform body, more slender
than that of a bluefin or a bigeye. Small eyes and head, longer 2nd dorsal
and anal fins than any other tuna (which get longer with age). The liver
is without striations on the ventral surface, and a swimbladder is present.
There are 26-35 gill rakers on the first gill arch. The pectoral fins
usually reach beyond the origin of the 2nd dorsal fin but not beyond the
end of its base.
Yellowfin have a dark blue back with a yellow lateral band
on the upper sides. The lower sides and belly are silvery-gray, often
with chains of white vertical lines and spots. The 2nd dorsal and anal
fins are yellow, and the finlets are yellow with a narrow black margin.
Size
Maximum: 75 inches
Common: 16 to 67 inches
Current IGFA all tackle record 388 pounds 12 ounces.
Distribution and Behavior
A warm-water species, yellowfin is the most tropical species
of tuna, and is abundant in tropical waters throughout the Atlantic. Young
are known to form large schools near surface. Adults inhabit fairly deep
water but also live near the surface.
Yellowfin are often found mixed with other species, especially
skipjack and bigeye. Yellowfin are sexually mature when they reach a length
of approximately 40 inches, and spawning occurs throughout the year in
the core areas of distribution (between 15 N and 15 S latitude), including
the Gulf of Mexico, with peaks occurring in summer months.
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ALBACORE
Thunnus alalunga
Distinctive Characteristics Albacore can be distinguished
from other tunas by a long pectoral fin that may reach to a point beyond
the anal fin. The pectoral fin in juvenile albacore may be similar to
that of yellowfin or bigeye. A swimbladder is present, but is poorly developed
and not evident in individuals smaller than about 25-32 gill rakers on
the first gill arch.
Albacore lack any stripes or spots on the lower flanks
and belly. The tail fin has a thin white trailing edge. There is no yellow
on the main fins, but the dorsal finlets are yellowish. The anal finlets
are silvery or dusky.
Size
Maximum: 50 inches
Common: 16-43 inches
Current IGFA all tackle record 88 pounds 2 ounces
Distribution and Behavior
A temperate species, found worldwide in tropical and warm
temperate seas. While albacore usually remain in tropical or warm waters,
they do make migrations into colder waters as far north as New England.
In the Atlantic, larger size classes (31-50 inches are associated with
cooler water bodies, while smaller individuals tend to occur in warmer
waters.
Albacore reach sexual maturity at about 37 inches in length,
and spawn during June-July in the sub-tropical western areas of both hemispheres
and throughout the Mediterranean Sea.
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BONITO
Sarda sarda
Distinctive Characteristics Bonito can be distinguished
from other tunas by the presence of seven or more (often 9-12) oblique
dark stripes on the dorsal side of the fish. The back of the fish is steel-blue
or blue-green and the flanks and belly are silvery to whitish. The body
is entirely covered with scales, which are very small except in the pectoral
region.
Bonito have large conical teeth on both the upper and lower
jaw. No swimbladder is present, and there are 16-24 gill rakers on the
first gill arch. The pectoral fins are very short, and there are 20-23
fin rays on the 1st dorsal fin. The right and left lobes of the liver
are elongate, while the center lobe is short.
Size
Maximum; 36 inches
Common: 25 inches
Current IGFA all tackle record 18 pounds 4 ounces
Distribution and Behavior
Bonito are common in tropical and temperate waters of the
Atlantic from Argentina to Nova Scotia, and from South Africa to Norway,
but they are rare in the Caribbean and Gulf of Mexico. Known to skip or
leap over the surface of the water when in pursuit of prey. Found in schools
15-20 miles offshore, but are also found close to shore.
Bonito reach sexual maturity at about 16 inches in length
and spawn in the western Atlantic in June and July. Spawning usually takes
place close to shore, in warm coastal waters.
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SKIPJACK
Katsuwonus pelamis
Distinctive Characteristics Skipjack can be distinguished
from other tunas by the presence of stripes on the belly. Usually 4-6
prominent, dark longitudinal stripes from the lower belly and sides toward
the tail. The top of the fish is a dark purplish-blue, and the lower flanks
and belly are silvery.
The pectoral and ventral fins are short, and the two dorsal
fins are separated at the base by a small interspace. The teeth are small
and conical. No swimbladder is present. There are 53-63 gill rakers on
the first fill arch, more than any other tuna.
Size
Maximum: 40 inches
Common: 16 to 28 inches
Current IGFA all tackle record 41 pounds 14 ounces
Distribution and Behavior
An oceanic species, found worldwide in tropical and subtropical
waters. Skipjack are common throughout the tropical Atlantic, and can
be found as far north as Massachusetts in summer, and as far south as
Brazil. Often schools with blackfin in the western Atlantic, with school
size reaching 50,000 individuals.
Skipjack tuna reach sexual maturity at about 18 to 20 inches
in length. Spawning occurs in spurts throughout the year in tropical waters,
and from spring to early fall in subtropical waters with the spawning
season becoming shorter with increased distance from the equator.
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BLACKFIN TUNA
Thunnus alanticus
Distinctive Characteristics Finlets are uniformly dusky
with only a trace of yellow, not bright lemon yellow like other tunas,
and may have white edges. The 1st dorsal fin is dusky; 2nd dorsal and
anal fins also dusky with a silvery luster. The back of the fish is bluish-black,
with the sides silvery-grey, and the belly milky white. Some have light
vertical stripes on sides which alternate with light spots on lower flanks.
Gill rakers are fewer in number than in other species of
Thunnus, with 19-25 on the first gill arch. A smzll swimbladder is present.
The ventral surface of the liver is without striations, and the right
lobe is longer than the left and center lobes.
Size
Maximum: 40 inches
Common: 28 inches
Current IGFA all tackle record 42 pounds 8 ounces
Distribution and Behavior
Blackfin are found in the tropical and warm temperate waters
of the western Atlantic. The range of this species extends from Brazil
to Cape Cod, including the Caribbean and the Gulf of Mexico. Blackfin
often feed near the surface, and they frequently form large mixed schools
with skipjack.
The blackfin's spawning grounds are believed to be well
offshore. Off Florida the spawning season extends from April to November
with a peak in May, while in the Gulf of Mexico it lasts from June to
September.
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LITTLE TUNNY
(False Albacore)
Euthynnus alletteratus
Distinctive Characteristics The little tunny is distinguished
by a scattering of dark spots, usually 4-5 resembling fingerprints between
the pectoral and ventral fins. This species also has wavy markings found
on the back above the lateral line, located within a well marked border
that never extends further forward than the middle of the first dorsal
fin.
The pectoral and ventral fins are short and broad, and
the two dorsal fins are separated at the base by a small interspace. The
teeth are small and conical. No swimbladder is present. There are 37-43
gill rakers on the first gill arch.
Size
Maximum: 40 inches
Common: 25 inches
Current IGFA all tackle record 35 pounds 2 ounces
Distribution and Behavior
Little tunny are common in the tropical and warm temperate
waters of the Atlantic from New England to Brazil in the west, and from
Great Britain to South Africa in the east. They are not as migratory as
other tuna species, and can be found regularly in inshore waters, as well
as offshore. Usually found in large schools.
Little tunny reach sexual maturity at approximately 15
inches in length. Spawning occurs from about April to November in both
the western and eastern Atlantic.
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INFORMATION AND CONTACTS
The information in this guide was compiled by the Highly
Migratory Species Management Division (HMS) of the National Marine Fisheries
Service. Fishers are responsible for complying with current official regulations
and since fishery rules are subject to change, fishers must familiarize
themselves with the latest regulations. In order to help keep the public
informed, HMS maintains an information line for news and catch reports
concerning Atlantic tunas. The HMS information line, which is updated
daily, announces closure notices, scooping and public hearing locations
and times, inseason quota adjustments, and updatres of landings of Atlantic
Bluefin tuna. Callers may reach the 24 hour information line by dialing
(508) 281-9305, (301) 713-1279,
or toll free at (888) USA-TUNA.
For further information concerning the Atlantic tuna
fisheries or the Cooperative Gamefish Tagging Program, or for complete
copies of current regulations, contact:
Rebecca Lent, Division Chief
Chris Rogers, Fisheries Management Specialist
Highly Migratory Species Management Division Office of Sustainable Fisheries
Silver Springs, MD 20910 Mark Murray-Brown,
Fisheries Mgmt. Specialist
(301) 713-2347
Highly Migratory Species Management Division Office of Sustainable
Fisheries
Gloucester,MA 01930
(508) 281-9208
Cooperative Gamefish Tagging Program
(800) 437-3936
24 Hour HMS Information Line:
(508) 281-9305
(301) 713-1279
(888) USA-TUNA
REFERENCES
Collette,B.B and C.E. Nauen, 1983. Scombrids of the World.
Food and Agriculture Organization of the United Nations, Rome, Italy.
Gibbs, R.H. and B.B. Collette, 1996. Comparative Anatomy
and Systematics of the Tunas, Genus Thunnus. Fishery Bulletin 66(1)
International Game Fish Association, 1995. 1995 World Record
Game fihes. International Game Fish Association, Pompano Beach, Florida
Smith, C.F. and E. Hasbrouck, 1998. a guide to Identifying
Tuna in New York Area Waters. Cornell Cooperative Extension of Suffolk
County, Marine Program, Riverhead, New York.
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