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Thunnus alalungaAhi pahala

By Michael Hwang

Geographic Range

Albacore reside in the subtropical regions of the North Pacific Ocean, Indian Ocean, North Atlantic Ocean, and Mediterranean Sea. In the North Pacific, albacore are distributed throughout a region from 10 to 50 degrees north latitude, with migration towards the tropical waters during spring and summer spawning months. Albacore occupy similar latitudes in the Atlantic Ocean, but young albacore have been caught by fishermen between 40 to 50 degrees north latitude. In the Indian Ocean, albacore are distributed throughout a region from 50 degrees north latitude to 40 degrees south latitude. In the north, immature albacore occupy 25 to 35 degrees north latitude, mature albacore occupy the north equatorial current region, and spawning albacore occupy the area near 20 degrees north latitude. To the south, mature albacore occupy an area north of 10 degrees south latitude, immature albacore occupy the area south of 30 degrees south latitude, and spawning albacore occupy the area in between (10 to 30 degrees south latitude). Note that for these migratory tuna, April to September are the non-spawning months and October to March are the spawning months in the Indian Ocean, while in the Atlantic, April to September are the spawning months. (Bard, 2001; Chen, et al., 2005; Watanabe, et al., 2004)

Habitat

Albacore have been found inhabiting depths of 0 to 600 m. Large albacore (~21 kg) typically occupy depths from 0 to 450 m, with a maximum abundance between 250 and 300 m. This 250 to 300 m depth has a water temperature of 25 to 15 degrees Celsius. While larger-bodied albacore tend to be active around cooler areas (some venture into deeper water ranging from 10 to 25 degrees Celsius), smaller-bodied albacore tend to occupy warmer layers. Being pelagic, they have no dependence on the sea floor. (Bard, 2001; Collette and Nauen, 1983)

  • Range depth
    0 to 600 m
    0.00 to 1968.50 ft

Physical Description

Albacore typically reach sexual maturity at a length of 90 cm. The maximum recorded size is 140 cm and 60.3 kg. Weight varies considerably within the species, with immature albacore weighing less than 14 kg and mature albacore weighing more than 14 kg. One of the most distinguishable traits of albacore are the extremely long pectoral fins. In individuals longer than 50 cm, the pectoral fin can be 30% of the fork length. Because the closely related bigeye tuna (Thunnus obesus) also have extremely long pectoral fins, albacore are often confused with juvenile bigeye tuna. Pectoral fins of bigeye tuna have rounded tips while pectoral fins of albacore have more pointed tips. Because bigeye tuna grow much larger than albacore, only juvenile bigeye tuna are misidentified as albacore. In addition to long pectoral fins, albacore have very small scales covering their body, 11 to 14 dorsal spines, 12 to 16 dorsal soft rays, 11 to 16 anal soft rays, and no anal spines. Because the anterior spines are longer than the posterior spines in the dorsal fin, the dorsal fin appears to have a concave outline pointing back toward the tail. Albacore have a faint blue iridescent band along the side of the body as well as yellow shades in the dorsal and anal fins. Males are similar to females in appearance and color, but begin to grow larger in size after sexual maturity due to different growth rates. (Chen, et al., 2005; Collette and Nauen, 1983)

  • Sexual Dimorphism
  • male larger
  • Range mass
    60.3 (high) kg
    132.82 (high) lb
  • Range length
    140 (high) cm
    55.12 (high) in

Development

Although albacore are closely related and quite similar to skipjack tuna and yellowfin tuna, they have different life history strategies. Skipjack tuna and yellowfin tuna are characterized by rapid growth and development, early maturation, and high energy input into gonad production. Albacore on the other hand, grow slow, mature late, and put relatively little energy into gonad production. The life stages of albacore include immature juveniles, non-spawning mature adults, and spawning mature adults. The eggs and larvae are planktonic, floating around the water column freely. The typical age of sexual maturity is five years. Up until the age of four, differences between males and females are negligible, but after that, males become increasingly larger than females. When captured, sex is determined by gonad analysis. (Essington, 2003; Santiago and Arrizabalaga, 2005)

Reproduction

Albacore are polygynandrous. They spawn as a group by simply releasing their eggs and sperm into the water. (Collette and Nauen, 1983)

Albacore are an iteroparous species that breed seasonally. Adults make a spawning migration toward more tropical waters during the summer months (April to September in the Northern Hemisphere, October to March in the Southern Hemisphere). Females lay eggs that are fertilized externally (oviparous). Albacore tend to scatter their eggs throughout the ocean. A 20 kg female can produce 2 to 3 million eggs in two batches. However, this varies by size. Albacore reach sexual maturity at about five years of age. (Collette and Nauen, 1983; Santiago and Arrizabalaga, 2005)

  • Breeding interval
    Albacore breed once yearly
  • Breeding season
    Albacore breed July to September in the Northern Hemisphere, October to March in the Southern Hemisphere
  • Average number of offspring
    2 million
  • Average age at sexual or reproductive maturity (female)
    5 years
  • Average age at sexual or reproductive maturity (male)
    5 years

Besides the contribution of their gametes and the energy expended migrating to spawning grounds, there is no parental investment by albacore. (Collette and Nauen, 1983)

  • Parental Investment
  • no parental involvement

Lifespan/Longevity

Males grow larger and to a later age in the Atlantic and Mediterranean. Maximum lifespan of albacore in the Atlantic is 13 years, while it is only 9 years in the Mediterranean. Before sexual maturity, the population sex ratio is 1:1. After maturity, males predominate due to differences in mortality and growth rate. (Collette and Nauen, 1983; Megalofonou, 2000)

  • Range lifespan
    Status: wild
    13 (high) years

Behavior

Albacore tuna are highly migratory and move with current systems during seasonal water movements. Albacore travel in large schools of mixed species that include skipjack tuna, yellowfin tuna and bluefin tuna. These schools are usually formed around floating objects such as sargassum weeds. (Chen, et al., 2005; Collette and Nauen, 1983; Watanabe, et al., 2004)

Communication and Perception

Little specific information is available on how albacore perceive their environment or communicate with others. However, they most likely perceive their environment through visual, auditory, tactile, and chemical means, as do most fish. (Von der Emde, et al., 2004)

Food Habits

The primary diet of albacore includes pacific saury, northern anchovy, crustacean zooplankton, gonatid squid, and Japanese anchovy. Albacore are opportunistic piscivores and their diet varies seasonally depending on location. Anchovy typically constitutes up to 96% of the stomach contents of albacore at any given time. Some studied fish fed on other schools of fish when encountered due to the patchy distribution of anchovy, demonstrating the opportunistic feeding habits of albacore. Albacore also exhibit a diel vertical migration pattern, following their prey throughout the water column. (Bernard, et al., 1985; Watanabe, et al., 2004)

  • Animal Foods
  • fish
  • mollusks
  • aquatic crustaceans
  • zooplankton

Predation

Many sharks, rays, larger tunas, and billfishes are predators that prey upon albacore. Because albacore are valuable commercial fish, humans are also important predators. (Collette and Nauen, 1983; Essington, 2003)

Ecosystem Roles

Albacore fall into the fourth trophic level in the oceanic ecosystem. Albacore are top predators that prey upon many aquatic species. (Watanabe, et al., 2004)

Economic Importance for Humans: Positive

Albacore are important commercially and are highly targeted by fisheries around the world, especially by Taiwan, Japan, and Korea. They are caught and sold fresh, frozen, or canned. (Chen, et al., 2005; Collette and Nauen, 1983)

  • Positive Impacts
  • food

Economic Importance for Humans: Negative

Current research is beginning to show that some tuna consumed by humans may exceed the Food and Drug Administration's original action level of 0.5 ppm mercury. Tuna marketed in stores as white tuna, such as albacore, contains twice as much mercury as skipjack tuna, which is typically marketed as light or chunk light tuna. This is not a major health issue right now, but it may be wise to perform further research on this inorganic metal contaminant in tuna. (Burger and Gochfeld, 2004)

Conservation Status

As a whole, albacore are not cited as endangered by any major organizations, but not enough information is available for a definitive classification. This is due to lack of fishing for albacore past certain depths. However, the north Atlantic stock of albacore is listed as vulnerable by the IUCN, and the south Atlantic stock is listed as critically endangered. (Bard, 2001; Uozumi, 2004)

Contributors

Allison Poor (editor), University of Michigan-Ann Arbor.

Michael Hwang (author), University of Michigan-Ann Arbor, Kevin Wehrly (editor, instructor), University of Michigan-Ann Arbor.

Glossary

Atlantic Ocean

the body of water between Africa, Europe, the southern ocean (above 60 degrees south latitude), and the western hemisphere. It is the second largest ocean in the world after the Pacific Ocean.

World Map

Pacific Ocean

body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.

World Map

acoustic

uses sound to communicate

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

external fertilization

fertilization takes place outside the female's body

fertilization

union of egg and spermatozoan

food

A substance that provides both nutrients and energy to a living thing.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

migratory

makes seasonal movements between breeding and wintering grounds

motile

having the capacity to move from one place to another.

natatorial

specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

pelagic

An aquatic biome consisting of the open ocean, far from land, does not include sea bottom (benthic zone).

phytoplankton

photosynthetic or plant constituent of plankton; mainly unicellular algae. (Compare to zooplankton.)

piscivore

an animal that mainly eats fish

polygynandrous

the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

saltwater or marine

mainly lives in oceans, seas, or other bodies of salt water.

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

tactile

uses touch to communicate

visual

uses sight to communicate

zooplankton

animal constituent of plankton; mainly small crustaceans and fish larvae. (Compare to phytoplankton.)

References

Bard, F. 2001. Extension of Geographical and Vertical Habitat of Albacore (Thunnus alalunga) in the North Atlantic Possible Consequences on True Rate of Exploitation of this Stock. ICCAT, 52/4: 1447-1456.

Bernard, H., J. Hedgepeth, S. Reilly. 1985. Stomach Contents of Albacore, Skipjack, and Bonito Caught Off Southern California During Summer 1983. CaCOFL Rep, 26: 175-183.

Burger, J., M. Gochfeld. 2004. Mercury in canned tuna: white versus light and temporal variation. Environmental Research, 96: 239-259.

Chen, I., P. Lee, W. Tzeng. 2005. Distribution of albacore (Thunnus albacore) in the Indian Ocean and its relation to environmental factors. Fisheries Oceanography, 14/1: 70-80.

Collette, B., C. Nauen. 1983. Scombrids of the world. An annotated and illustrated catalogue of tunas, mackerels, bonitos and related species known to date. FAO species catalogue, 2: 137.

Essington, T. 2003. Development and Sensitivity Analysis of Bioenergetics Models for Skipjack Tuna and Albacore: A Comparison of Alternative Life Histories. Transactions of the American Fisheries Society, 132: 759-770.

Megalofonou, P. 2000. Age and growth of Mediterranean albacore. Journal of Fish Biology, 57: 700-715.

Santiago, J., H. Arrizabalaga. 2005. An integrated growth study for North Atlantic albacore (Thunnus alalunga Bonn. 1788). Journal of Marine Science, 62: 740-749.

Uozumi, Y. 2004. "Thunnus alalunga" (On-line). 2004 IUCN Red List of Threatened Species. Accessed December 16, 2005 at www.redlist.org.

Von der Emde, G., J. Mogdans, B. Kapoor. 2004. The senses of fish : adaptations for the reception of natural stimuli. Boston: Kluwer.

Watanabe, H., T. Kubodera, S. Masuda, S. Kawahara. 2004. Feeding habits of albacore Thunnus alalunga in the transition region of the central North Pacific. Fisheries Science, 70: 573-579.

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