''Euthynnus lineatus'', the black skipjack tuna or black skipjack, is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

ray-finned Actinopterygii (; ), members of which are known as ray-finned fish or actinopterygians, is a class of bony fish that comprise over 50% of living vertebrate species. They are so called because of their lightly built fins made of webbings of skin ...

bony fish Osteichthyes ( ; ), also known as osteichthyans or commonly referred to as the bony fish, is a Biodiversity, diverse clade of vertebrate animals that have endoskeletons primarily composed of bone tissue. They can be contrasted with the Chondricht ...

in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Scombridae The mackerel, tuna, and bonito family, Scombridae, includes many of the most important and familiar food fishes. The family consists of 51 species in 15 genera and two subfamilies. All species are in the subfamily Scombrinae, except the but ...

. It belongs to the

tribe The term tribe is used in many different contexts to refer to a category of human social group. The predominant worldwide use of the term in English is in the discipline of anthropology. The definition is contested, in part due to conflict ...

Thunnini A tuna (: tunas or tuna) is a saltwater fish that belongs to the tribe Thunnini, a subgrouping of the Scombridae (mackerel) family. The Thunnini comprise 15 species across five genera, the sizes of which vary greatly, ranging from the bulle ...

, better known as the

tuna A tuna (: tunas or tuna) is a saltwater fish that belongs to the tribe Thunnini, a subgrouping of the Scombridae ( mackerel) family. The Thunnini comprise 15 species across five genera, the sizes of which vary greatly, ranging from the bul ...

s. It is in the genus

Euthynnus ''Euthynnus'' is a genus of ray-finned bony fish in the family Scombridae, or mackerel family, and in the tribe Thunnini, more commonly known as the tunas. Species in the genus ''Euthynnus'' are also known as "little tunas," and are found in sub ...

of "little tunas" which includes the

little tunny The little tunny (''Euthynnus alletteratus''), also known as the little tuna, false albacore, or erroneously as the blue bonito, is a species of tuna in the family Scombridae. It can be found in the Atlantic Ocean and the Mediterranean and B ...

from the Atlantic Ocean and kawakawa, from the Indo-Pacific Ocean, which also shares some range with the black skipjack.

Description

''E. lineatus'' has a total of 10-15 spines in its

dorsal fin A dorsal fin is a fin on the back of most marine and freshwater vertebrates. Dorsal fins have evolved independently several times through convergent evolution adapting to marine environments, so the fins are not all homologous. They are found ...

s with the anterior spines of the first dorsal fin being much taller than the middle spines which gives this fin a concave outline. The

anal fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported o ...

has 11 - 12 soft rays and it has a vertebra count of 37. Its body is almost entirely scaleless except for the

lateral line The lateral line, also called the lateral line organ (LLO), is a system of sensory organs found in fish, used to detect movement, vibration, and pressure gradients in the surrounding water. The sensory ability is achieved via modified epithelia ...

and a "corselet", and there is no

swim bladder The swim bladder, gas bladder, fish maw, or air bladder is an internal gas-filled organ (anatomy), organ in bony fish that functions to modulate buoyancy, and thus allowing the fish to stay at desired water depth without having to maintain lift ...

. It is generally iridescent blue in colour with black markings on its back made up of 3 to 5 horizontal stripes, as well as a variable amount of black or dark grey spots above the

pelvic fins Pelvic fins or ventral fins are paired fins located on the ventral (belly) surface of fish, and are the lower of the only two sets of paired fins (the other being the laterally positioned pectoral fins). The pelvic fins are homologous to the hi ...

. Occasional specimens have extensive longitudinal stripes of light grey on their belly while other individuals have few or no such markings. After death, the lines are often no longer prominent, but can still be distinguished by the 2 or more spots over the pelvic fins. ''E. lineatus'' can reach up to and a weight up to . Euthynnus lineatus

Distribution

Eastern tropical Pacific from

San Simeon San Simeon ( Spanish: ''San Simeón'', meaning "St. Simon") is an unincorporated community on the Pacific coast of San Luis Obispo County, California, United States. Its position along State Route 1 is about halfway between Los Angeles and San ...

California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

to northern

Peru Peru, officially the Republic of Peru, is a country in western South America. It is bordered in the north by Ecuador and Colombia, in the east by Brazil, in the southeast by Bolivia, in the south by Chile, and in the south and west by the Pac ...

and the

Galápagos Islands The Galápagos Islands () are an archipelago of volcanic islands in the Eastern Pacific, located around the equator, west of the mainland of South America. They form the Galápagos Province of the Republic of Ecuador, with a population of sli ...

Fisheries

No targeted fishery exists for this species, though it is taken incidentally in the course of other fishery operations. Like the closely related

, its meat is regarded as subpar due to it being very bloody and red, and is often thrown back.

Biology

''E. lineatus'' is a

pelagic The pelagic zone consists of the water column of the open ocean and can be further divided into regions by depth. The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or water column between the sur ...

and oceanodromous species which is rarely recorded where the surface temperature falls below . The larvae are most commonly found at temperatures higher than . It is generally distributed in surface waters which are no more than from land. ''E. lineatus'' will form multi-species schools other scombridaes like the

yellowfin tuna The yellowfin tuna (''Thunnus albacares'') is a species of tuna found in pelagic waters of tropical and subtropical oceans worldwide. Yellowfin is often marketed as ahi, from the Hawaiian , a name also used there for the closely related bigeye ...

and

skipjack tuna The skipjack tuna (''Katsuwonus pelamis'') is a perciform fish in the tuna family, Scombridae, and is the only member of the genus ''Katsuwonus''. It is also known as katsuo, arctic bonito, mushmouth, oceanic bonito, striped tuna or victor fish. ...

. It shows opportunistic predatory behavior, sharing its feeding pattern with other tunas, as well as dolphins and other large predatory fish, with which it also competes. Like other

s, the fish breaths through ram ventilation, so it must continue swimming to intake oxygen. The spawning of this species has a wide geographical and temporal distribution, and in the eastern tropical Pacific it has been shown to occur over a wide area from coastal to oceanic waters.

References

External links

{{Taxonbar, from=Q1999309 lineatus Fish described in 1920