The tuna is not a single fish
species, but in fact a complex of large pelagic
planktivores of the family
Scombridae. They are of tremendous importance
economically to many countries, and are often the subject of study by
biologists as a result of their interesting
physiology.
The following list provides the names (both scientific and common), ranges
and sizes (maximum length / weight) of those species most common in the ocean
and in commercial catches.
- Albacore (Thunnus alalunga) -- (70 cm/40 kg) Fished in the northern
and southern Pacific, Atlantic and Indian
oceans. Highly migratory, spawn in southern Pacific and Atlantic,
and Indian oceans.
- Bigeye (Thunnus obesus) -- (85 cm/20 kg) Fished in eastern and
western Pacific, southern Atlantic and Indian oceans. Deeper water species, and
thus they have a higher fat content in their flesh, making them particularly
attractive to the Japanese market.
- Northern bluefin (Thunnus thynnus) -- (458 cm/684 kg max.) Fished in
the north-west Pacific, Northern Atlantic and Mediterranean. Another species
which undertakes large migrations, it is also the slowest growing tuna species
making it highly vulnerable to over-fishing.
- Southern bluefin (Thunnus thynnus) -- (200 cm/220 kg max.) Fished in
the southern Pacific and Atlantic, as well as the Indian ocean. This species is
the most highly sought-after by the Asian markets. It is also a slow-growing
species, as is under the greatest pressure from commercial fisheries.
- Skipjack (Katsuwonus pelamis) -- (108 cm/35 kg) Fished in the eastern
and western Pacific, as well as the Indian and Atlantic oceans. It is a surface
species, reaching a smaller maximum size than other species. It is fast growing,
and thus fairly resistant to over-fishing.
- Longtail (Thunnus tonggol) -- (100 cm/35 kg) Fished in the western
Pacific and Indian oceans. Mostly used for canned tuna, and particularly
targeted by Thai local fisheries.
- Yellowfin (Thunnus albacares) -- (180 cm/175 kg) Fished in the
Pacific and Indian oceans, as well as the southern Atlantic. This species is the
second most coveted by the fisheries, and is among the most migratory and rapid
of all tuna species.
The various tuna species are of particular interest to the scientific community
for several resaons. They never stop moving during their entire lifespan, and
feed in a passive manner called
ram ventilation. They also have the ability to
raise their body temperature a couple of degrees above that of
their environment as a result of the action of their muscles. In this, they are
practically alone in the
teleost division.
Much of the information used to create this post was taken from Atuna, a
fishery organization (http://www.atuna.com), as well as World Tuna Development
International (http://www.worldtuna.com). Many additional governmental web sites
were also used to flesh out the details