Thunnus obesus
Bigeye Tuna
NS
GNR
Collection Details
Specimens
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Taxonomic Hierarchy
Actinopterygii (Ray-finned Fishes)
Perciformes (Perciformes, Also Called the Acanthopteri)
Scombridae (Mackerels)
Thunnus
Thunnus obesus (Bigeye Tuna)
Description
This species account was compiled from
Composite (multiple sources) (McEachran, J.D. and J.D. Fechhelm. Fishes of the Gulf of Mexico. University of Texas Press, Austin.)
and processed using AI-assisted text extraction.
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Characters
Narrowly separated dorsal fins, moderately long pectoral fins, poorly developed corselet of scales on anterior section of body. Body profile is subelliptical, with maximum girth near middle of first dorsal fin base. Snout is acute and conical. Jaw teeth are small, conical, and uniserial. Teeth are present or absent in vomer and palatine. Gill rakers on first arch number 23 to 31. Pectoral fin is falcate, extends almost to anal fin origin, and has 30 to 36 rays. First dorsal fin is high anteriorly and has a concave margin and 11 to 14 spines. Second dorsal fin is sickle shaped, has 12 to 16 rays, and is followed by 7 to 10 finlets. Interpelvic process is small and bifid. Anal fin is similar to second dorsal fin in size and shape, has 11 to 16 rays, and is followed by 7 to 10 finlets. Caudal peduncle bears a long midlateral keel between two shorter oblique keels. Body is covered with small scales, and corselet of large scales extends over nape, anterior section of lateral line, and thorax region. Vertebrae number 39: 18 precaudal and 21 caudal. Gas bladder is present. Liver in ventral view has striations resulting from blood vascular network, and right lobe is not longer than other lobes.
Color is metallic dark blue dorsally and white ventrally. Live specimens have iridescent blue stripe on side. First dorsal fin is deep yellow, second dorsal and anal fins are light yellow, and finlets are yellow with black margins.
Distribution
In the western Atlantic it occurs from southern Nova Scotia and Bermuda to Brazil, including the Gulf of Mexico;
It is rare in the Straits of Florida and in the Gulf of Mexico.
Habitat Associations
Tropical to subtropical seas at epipelagic and mesopelagic depths, between the surface and 250 m.
Biology
Food consists of cephalopods, crustaceans, and ray-finned fishes.
Maximum known size is 239 cm FL. Maximum known age is over three years.
Spawning may take place year-round in tropical waters.
Occur in areas where water temperatures range from 13°-29°C, but the optimum is between 17° and 22°C. Variation in occurrence is closely related to seasonal and climatic changes in surface temperature and thermocline. Juveniles and small adults school at the surface in mono-species groups or mixed with other tunas, may be associated with floating objects. Adults stay in deeper waters (Ref. 5377). Eggs and larvae are pelagic (Ref. 6390). Feed on a wide variety of fishes, cephalopods and crustaceans during the day and at night (Ref. 9340). Meat is highly prized and processed into sashimi in Japan. Marketed mainly canned or frozen (Ref. 9684), but also sold fresh (Ref. 9340).
IUCN Red List Status: Vulnerable (VU), assessed 2021-01-15. Resilience: Medium (K=0.11-0.23; tm=3; tmax=11; Fec=2 million).
Commercial or Environmental Importance
Fisheries: highly commercial; gamefish.
References
Collette 1986b
Collette 2001e
Collette 2002g
Collette and Nauen 1983
Robins and Ray 1986
Scott and Scott 1988
Schaldach et al. 1997
Smith 1997
Smith-Vaniz et al. 1999
Collette, B.B. and C.E. Nauen (1983) FAO Species Catalogue. Vol. 2. Scombrids of the world. An annotated and illustrated catalogue of tunas, mackerels, bonitos and related species known to date. Rome: FAO. FAO Fish. Synop. 125(2):137 p.
Fuentes, H., E. Antonietti and A. Alano (1988) Espectro alimentario del patudo (Thunnus obesus) en la primavera austral de 1986 en el Pacifico sur oriental. In H. Salzwedel and A. Landa (eds.) Recursos y Dinámica del Ecosistema de Afloramiento Peruano. Bol. Inst. Mar. del Perú, Volumen Extraordinario.
Collette, B.B. (2001) Scombridae. Tunas (also, albacore, bonitos, mackerels, seerfishes, and wahoo). p. 3721-3756. In K.E. Carpenter and V. Niem (eds.) FAO species identification guide for fishery purposes. The living marine resources of the Western Central Pacific. Vol. 6. Bony fishes part 4 (Labridae to Latimeriidae), estuarine crocodiles. FAO, Rome.
Reiner, F. (1996) Catálogo dos peixes do arquipélago de Cabo Verde. Publ. Avuls. Inst. Port. Invest. Mar. 2:339 p.
Patzner, R.A. (2008) Reproductive strategies of fish. pp. 311-350. In Rocha, M.J., A. Arukwe and B.G. Kapoor (eds). Fish reproduction: cytology, biology and ecology. Science Publisher, Inc. Oxford. 631 p.
Collette et al. (2011) Thunnus obesus. The IUCN Red List of Threatened Species 2011: e.T21859A9329255. http://dx.doi.org/10.2305/IUCN.UK.2011-2.RLTS.T21859A9329255.en. Downloaded on 31 January 2018.
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