Thunnus alalunga
albacore
(Also: atún blanco; germon; longfinned albacore)

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, Lee, and Tzeng, 2005; Watanabe et al., 2004)

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)

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, Lee, and Tzeng, 2005; Collette and Nauen, 1983)

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)

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)

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, Lee, and Tzeng, 2005; Collette and Nauen, 1983; Watanabe et al., 2004)

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, Mogdans, and Kapoor, 2004)

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, Hedgepeth, and Reilly, 1985; Watanabe et al., 2004)

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)

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)

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)

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, Lee, and Tzeng, 2005; Collette and Nauen, 1983)

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)