Euthynnus

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Euthynnus
Euthynnus affinis

Euthynnus affinis

Systematics
Acanthomorphata
Spinefish (Acanthopterygii)
Perch relatives (Percomorphaceae)
Order : Scombriformes
Family : Mackerel and tuna (Scombridae)
Genre : Euthynnus
Scientific name
Euthynnus
Luetken , 1882

Euthynnus is aspecies of marine fish closely relatedto the tuna ( Thunnus ) that occurs worldwide in tropical and subtropical seas.

features

Euthynnus species are 80 cm to one meter long and have a strong, spindle-shaped body with a pointed head and a terminal mouth. The teeth are small, conical and lined up in a row in each jaw (25 to 35 per row). The palate is also toothed. The first gill arch has 29 to 45 gill rakes and 28 to 32 pharyngeal teeth . Except for a scaly corset on the front body and a row of scales along the sidelines , the fish are scaly. The two dorsal fins are only separated by a narrow gap that is no larger than the diameter of the eye. The first is supported by 10 to 15 fin spines, the first of which are much higher than the last, so that the upper edge of the fin is concave. The second dorsal fin is lower than the first. Between the second dorsal fin and the caudal fin stand 8 to 10 rafts. The anal fin has 11 to 15 fin rays. Between it and the caudal fin there are 6 to 8 rafts. The pectoral fins are short, never reach the space between the two dorsal fins and have 25 to 29 fin rays. The tail stalk is slender and has a strong, bony side keel between two smaller keels for stabilization. A swim bladder is missing. The number of vertebrae is 37 to 39.

Euthynnus species have a dark blue-black or an iridescent green ( E. affinis ) back which is additionally drawn with a complicated stripe pattern behind the middle of the first dorsal fin. The sides of the body and the belly are silvery and without dark vertical stripes. There are some characteristic dark spots between the pectoral and pelvic fins that are not always clearly visible.

Way of life

The Euthynnus species live near the coast, the range of the three species does not overlap. They are rarely found in areas with surface temperatures below 20 to 23 ° C, and they spawn at high water temperatures. Euthynnus are opportunistic predatory fish that feed on fish, pelagic crustaceans , cephalopods, and salps . Together with other tuna and mackerel species, they form mixed shoals of the same size. At certain times of the year, however, the swarms disperse. Euthynnus species themselves are hunted by large tuna, swordfish-like fish and sharks.

species

There are three types:

fishing

Of all three species, Euthynnus affinis is particularly important for fishing and is caught in large quantities in Southeast Asia with longlines , purse seine and drift nets .

literature

  • Bruce B. Collette, Cornelia E. Nauen: Scombrids of the world. An annotated and illustrated catalog of tunas, mackerels, bonitos and related species known to date (= FAO Species Catalog. Vol. 2 = FAO Fisheries Synopsis. No. 125, Vol. 2). United Nations Development Program et al., Rome 1983, ISBN 92-5-101381-0 .

Web links

Commons : Euthynnus  - collection of images, videos and audio files