Description: A very large tuna. Body fusiform, elongate, and slightly compressed. Body deepest near the middle of the first dorsal fin base. Second dorsal fin higher than the first. Pectoral fins very short. Back metallic dark blue; lower sides and belly silvery white with colourless transverse lines alternated with rows of colourless dots, visible only in fresh specimens. First dorsal fin yellow or bluish; the second reddish-brown. Anal fins and finlets dusky yellow edged with black; median caudal keel black in adults.
Growth type: Juvenile growth is rapid (about 30 cm / year) but slower than in other tuna and billfish species. Adult growth is considerably slower, with about 10 years needed to reach two thirds of maximum length.
von Bertallanfy growth parameters:
Reproduction: Eggs and larvae are pelagic.
Maturity: range 97 - 110 cm.
Behavioural ecology: They school by size, sometimes together with other tunas, e.g. albacore, yellowfin, bigeye, skipjack etc.
Population structure & migrations: Highly migratory species.
ECOLOGICAL FEATURES
Depth range: FishBase: 0 - 985 m, usually 0 - 100 m.
Habitat: Oceanic but seasonally coming close to shore.
Feeding habits: Visual predators, preying on small schooling fishes (anchovies, sauries, hakes), squids and red crabs.
Trophic level: FishBase: 4.4
FISHERIES
Commercial interest: Highly valued commercial species, it has suffered a strong decline in recent years.
Conservation status: Global: Endangered.
Europe: Near threatened.
Nutritional information & food safety:
REFERENCES
Collette B.B., Nauen C.E. (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. FAO Fisheries Synopses, 125 vol.2, 137 pp.
IUCN (2014). The IUCN Red List of Threatened Species. Version 2014.1. www.iucnredlist.org
Nieto A., Ralph G.M., Comeros-Raynal M.T., Kemp J., GarcÃa Criado M., Allen D.J., Dulvy N.K., Walls R.H.L., Russell B., Pollard D., GarcÃa S., Craig M., Collette B.B., Pollom R., Biscoito M., Labbish Chao N., Abella A., Afonso P., Ãlvarez H., Carpenter K.E., Clò S., Cook R., Costa M.J., Delgado J., Dureuil M., Ellis J.R., Farrell E.D., Fernandes P., Florin A-B., Fordham S., Fowle, S., Gil de Sola L., Gil Herrera J., Goodpaster A., Harvey M., Heessen H., Herler J., Jung A., Karmovskaya E., Keskin C., Knudsen S.W., Kobyliansky S., KovaÄić M., Lawson J.M., Lorance P., McCully Phillips S., Munroe T., Nedreaas K., Nielsen J., Papaconstantinou C., Polidoro B., Pollock C.M., Rijnsdorp A.D., Sayer C., Scott J., Serena F., Smith-Vaniz W.F., Soldo A., Stump E., Williams J.T. (2015). Europen Red List of Marine Fishes. IUCN and European Union, Publications Office of the European Union, Luxembourg, 90 pp.
