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.
- Biogeographic Regions
- indian ocean
- atlantic ocean
- pacific ocean
- mediterranean sea
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.
- Habitat Regions
- saltwater or marine
- Aquatic Biomes
- pelagic
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.
- Other Physical Features
- ectothermic
- bilateral symmetry
- Sexual Dimorphism
- male larger
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.
Reproduction
Albacore are polygynandrous. They spawn as a group by simply releasing their eggs
and sperm into the water.
- Mating System
- polygynandrous (promiscuous)
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.
- Key Reproductive Features
- iteroparous
- seasonal breeding
- gonochoric/gonochoristic/dioecious (sexes separate)
- sexual
- fertilization
- broadcast (group) spawning
- oviparous
Besides the contribution of their gametes and the energy expended migrating to spawning
grounds, there is no parental investment by
albacore
.
- 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.
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.
- Key Behaviors
- natatorial
- motile
- migratory
- social
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.
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.
- Animal Foods
- fish
- mollusks
- aquatic crustaceans
- zooplankton
- Plant Foods
- phytoplankton
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.
Ecosystem Roles
Albacore
fall into the fourth trophic level in the oceanic ecosystem.
Albacore
are top predators that prey upon many aquatic species.
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.
- 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.
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.
Additional Links
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.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- 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.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- 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.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- saltwater or marine
-
mainly lives in oceans, seas, or other bodies of salt water.
- pelagic
-
An aquatic biome consisting of the open ocean, far from land, does not include sea bottom (benthic zone).
- ectothermic
-
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
- 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.
- polygynandrous
-
the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.
- 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).
- 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
- fertilization
-
union of egg and spermatozoan
- external fertilization
-
fertilization takes place outside the female's body
- oviparous
-
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
- natatorial
-
specialized for swimming
- motile
-
having the capacity to move from one place to another.
- migratory
-
makes seasonal movements between breeding and wintering grounds
- social
-
associates with others of its species; forms social groups.
- visual
-
uses sight to communicate
- tactile
-
uses touch to communicate
- acoustic
-
uses sound to communicate
- chemical
-
uses smells or other chemicals to communicate
- zooplankton
-
animal constituent of plankton; mainly small crustaceans and fish larvae. (Compare to phytoplankton.)
- phytoplankton
-
photosynthetic or plant constituent of plankton; mainly unicellular algae. (Compare to zooplankton.)
- food
-
A substance that provides both nutrients and energy to a living thing.
- carnivore
-
an animal that mainly eats meat
- piscivore
-
an animal that mainly eats fish
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.