What is a Tuna?

Mary McMahon
Mary McMahon

There are nine recognized species of tuna, which is a marine fish which spends the majority of its life in the middle depths of open water. Tuna is probably the most widely commercially harvested fish family, with more being landed every year by heavy producers such as Japan, France, the United States, Taiwan, and Spain. The meat appears in a wide range of traditional foods as well as canned, and the growing numbers of tuna being fished have raised concerns about the longevity of the family.

Raw tuna steaks.
Raw tuna steaks.

All tuna species are fished commercially, but Bluefin, Yellow fin, Albacore, and Skipjack are the most heavily fished. Bluefin, in particular, is highly prized in Japan, where the fish of the highest quality is used in sushi and sashimi. Albacore and Skipjack are often cooked and canned in oil or water for sale throughout the world, and Yellow fin is frequently labeled as “Ahi” for sale in Hawaii and along the Western coast of the United States.

A whole, fresh-caught Bluefin tuna.
A whole, fresh-caught Bluefin tuna.

Tuna tends to have darker meat than some other fish species, which stands up well to grilling and other robust cooking operations. The meat is high in protein and Omega 3, but unfortunately also accumulates mercury, like many fish species. As a result, consumers should limit their consumption, with some biologists recommending a serving or less per month for some species, particularly Bluefin.

Canned albacore tuna.
Canned albacore tuna.

This fish has traditionally been caught for commercial use in large nets, many of which inadvertently capture dolphins as well. After a public awareness campaign about the affectionate marine mammals encouraged a boycott of the tuna industry, many commercial companies began taking steps to prevent dolphins from being caught along with their tuna, billing the result as “dolphin safe.” Some is also caught on long lines, especially by sport fishermen who enjoy doing battle with the muscular and determined fish.

Nigiri sushi assortment, with a bluefin tuna piece in the middle.
Nigiri sushi assortment, with a bluefin tuna piece in the middle.

Tuna is popular among humans because it does not have a strong fishy flavor, and consumers who do not like fish will often eat tuna. It is an extremely versatile fish, thanks to the sturdy flesh, and can be found canned, dried, fermented, and fresh across most of the world. Fresh fish is landed daily at major fish markets in the United States, Asia, and Europe, and can be accessed by consumers within days, with some species such as the prized Bluefin being processed as rapidly as possible to ensure freshness.

Because the fast swimming fish has been heavily harvested, many conservation organizations have sounded warnings about the health of tuna stocks, particularly the southern Bluefin, which is considered to be endangered. Other species are in questionable health as well, with many nations taking large illegal harvests in addition to their internationally agreed upon quota. Tuna catches are declining in numbers, particularly in the Atlantic, where severe restrictions were undertaken in the early 21st century in an attempt to restore stocks of the fish.

Some nations have experimented with tuna farming successfully, and a growing number of the fish for sale is farmed tuna, providing an ecologically sustainable alternative to concerned consumers. Bluefin in particular has proven to be amenable to aquaculture in Australia, suggesting that in addition to providing human food, the farmed fish may be able to replenish depleted wild stocks as well.

"Dolphin safe" tuna is tuna that was collected without harming dolphins.
"Dolphin safe" tuna is tuna that was collected without harming dolphins.
Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a wiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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Discussion Comments


@feasting – Tuna does taste good with teriyaki sauce. I used to buy these cooked tuna steaks in packages that were smothered in this sauce, and they were so delicious!

They were very affordable. One steak was more than enough for lunch.

I was really sad when the grocery stores in the area stopped carrying them. I would love to get my hands on a good teriyaki tuna steak again! If I ever see them for sale anywhere, I'm stocking up.


My mother hates the taste of fish, but she will eated canned tuna. I have even caught her trying out a tuna recipe or two before.

She made a tuna loaf, which is like meat loaf but with fish. I'm not sure what all was in it, but I did see several macaroni noodles in the mix.

Her favorite lunch is a tuna salad sandwich. She mixes the tuna with pickles, a hard-boiled egg, and mayonnaise, and it tastes so much better than plain tuna out of the can.


Albacore tuna is the kind I see most often in cans on the supermarket shelves. I sometimes buy it and mix it with teriyaki sauce for extra flavor.

I like to heat the tuna with the sauce in a pain with green onions and corn. The flavors mesh well, and the dish is a healthy one.

I have to be sure to get all the tuna out of the can before I throw it in the trash. Tuna has a strong odor that only gets worse after a day or two in the trash.


I didn't know that Bluefin tuna was the stuff used in sushi! I also had no idea that I should only be eating it about once a month.

Sushi is my favorite food, and I go to a Japanese restaurant and order it at least two times a month. I suppose I should switch to the sushi that just contains crab and shrimp instead of tuna.

The menu never said what kind of tuna was in the sushi, but this is a high quality place, so it probably is Bluefin. I will have to warn my friends!


On one of my visits to the northern Adriatic I noticed some reminders of tuna fishing equipment. There are a number of something that looks like wooden stairs, the bottom of which is attached to the land and the top protruding way over the water. One fisherman would go to the top of those stairs, I was told, and wait for tuna to come within view, he would then signal to the rest of the fisherman who would catch them in nets. There is no more tuna in those parts of the Adriatic, just some reminders of times gone by.

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