The albacore (Thunnus alalunga) is a species of tuna in the family Scombridae.
The albacore tuna’s pectoral fin is extremely long and extends well beyond the front of the anal fin except in tuna under 30 cm long. Its average size is about 1.4 m and can weigh up to 60 kg. The albacore’s fins consist of seven to 9 dorsal finlets, seven or eight anal finlets, and 25-31 gill rakers. This tuna is dark blue dorsally, and shades of silvery white ventrally. The first dorsal fin is a deep yellow. The second dorsal fin and the anal fin are a light yellow. The caudal fin is white-edged, while the anal finlets are dark.
This species is also called albacore fish, albacore tuna, albicore, albie, pigfish, tombo ahi, binnaga, Pacific albacore, German bonito (but see bonito), longfin, longfin tuna, longfin tunny, or even just tuna. It is the only tuna species which may be marketed as “white meat tuna” in the United States. It is found in the open waters of all tropical and temperate oceans, and the Mediterranean Sea.
Albacore is a prized food, and the albacore fishery is economically significant. Methods of fishing include pole and line, long-line fishing, trolling, and some purse seining. It is also sought after by sport fishers.
During spawning, females produce between 800,000 and 2.6 million eggs which hatch in about one or two days. After the eggs hatch, the fish begin to grow quickly and they remain close to the place where they were hatched for the first year of their lives. They begin to migrate after their first year. Albacore tuna have a lifespan of 11 to 12 years, but they reach reproductive maturity at around five to six years.
Despite having no sexual dimorphism, tuna are dioecious (males and females have different sexual organs). Oddly, a large majority of tuna have heavier and larger right testes and ovaries in males and females, respectively. Their eggs, which mature and hatch outside of the female’s body, are typically restricted from November to February for spawning. Albacore have asynchronous oocyte development. An oocyte, which is an immature egg cell, does not develop at regular intervals in albacore. The creation of ova, known as ooegenesis, begins with the rapid production of oogonia (undifferentiated germ cells that give rise to oocytes) by mitotic separations in the oogonial nests of female tuna. The resulting oocytes are cast en masse into the sea, where full development and later fertilization take place.
Albacore tuna are pelagic predators – open-sea hunters. Their diets vary very little during the different seasons. Distinct from its two counterparts bigeye and yellowfin tuna that primarily eat fish, albacore tuna’s main source of food is cephalopods, which are also eaten by the other two species of tuna, albeit in smaller proportions. The most abundant cephalopods in its diet are Heteroteuthis dispar (a tiny deep-water squid found in the Mediterranean Sea and Atlantic Ocean). Other food sources of the albacore include fish, crustaceans, and gelatinous organisms. Not much is known about the food pattern of albacore tuna, however, mostly because they dive over 400 m underwater when searching for food, and tagging and tracking them has been unsuccessful thus far.
The North Pacific albacore migrate to two regions of the Northeast Pacific; one is off the northern part of Baja California, Mexico, and the other is off the coast of Washington and Oregon. Albacore tuna show a broad range of behavioral differences. In Baja California, the tuna make frequent dives to depths exceeding 200 m (660 ft) during the day and stay near the surface at night, while off the coast of Washington and Oregon the tuna stay near the surface the entire day. The albacore never really rest; they must always be on the move because of their demand for oxygen. Due to so much energy being used by the constant movement, a typical tuna may eat one-quarter its own weight in food in one day. The northeast albacore tuna performs feeding migrations to productive areas of the Northeast Atlantic during the summer. Due to climate change over the last 40 years, the timing and spatial distribution of the albacore tuna has also changed. Every summer, the North Atlantic albacore tuna head to the Bay of Biscay, but now arrive about 8 days earlier than they did 40 years ago.