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Everything You Need to Know About Tuna: A Comprehensive Overview


Tuna is one of the most popular and widely consumed fishes worldwide, known for its tasty and versatile flesh. In this article, we will delve into its characteristics, the different species, the fishing techniques employed, its nutritional benefits, and the various cuts that make it highly appreciated in global cuisine.


General Characteristics of Tuna – One of the Fastest Predators of the Oceans:

A drawing of a tuna.

The tuna is a fish with an elongated and hydrodynamic body, adapted for long migrations in tropical or subtropical oceanic waters. Its mouth is large and equally elongated, and its two dorsal fins are well separated and followed by groups of lepidotrichia. Its caudal fin is forked.

This fish is known for its rapid speed and strength, characteristics that make it an exciting challenge for fishermen. Tuna, and its neighboring species, also have the ability to raise their body temperature above the water temperature where they swim, due to their specialized vascular system. For this reason, they can swim across entire oceans. In a single day, they can swim up to 170 km.

Normally, they form schools with specimens of the same age that can reach hundreds or thousands of individuals.

They are active predators, feeding primarily on other fish, crustaceans, and squid.

Its red flesh is rich in proteins and has a firm and succulent texture, making it ideal for a variety of culinary preparations.


Tuna Species – Delve Deeper into One of the World’s Most Famous Fish:

There are fourteen species of tuna, belonging to 4 genera, each with its own distinct characteristics. Some of the most well-known species include:

1 – Bluefin Tuna (Thunnus thynnus): Known for its dark pink flesh and bold flavor, bluefin is one of the most commercially valuable species. This species can be identified by its shorter pectoral fin, silver-colored flanks and ventral region with a series of transverse lines, reddish-brown dorsal fin, and dark yellow-bordered anal fin and finlets.

A Bluefin tuna.

2 – Bigeye Tuna (Thunnus obesus): This species has pink flesh and is often found in tropical waters. It is highly prized in Madeira Island for its delicious flavor. It is distinguished by its large eye (larger than other species), long pectoral fin, yellow color of the 1st dorsal fin, light yellow color of the 2nd dorsal and anal fins, and yellow finlets bordered with black.

A Bigeye tuna.

3 – Yellowfin Tuna (Thunnus albacares): Also known as yellow tuna, this is one of the most common types, valued for its light flesh and mild flavor. It is distinguished by its long pectoral fin and very long 2nd dorsal and anal fins, both of a bright yellow color.

A yellowfin tuna.

4 – Albacore Tuna (Thunnus alalunga): This species of tuna has a pinkish-white flesh. It is distinguishable from other species by its very long pectoral fin, dark yellow color of the 1st dorsal fin, yellow color of the 2nd dorsal and anal fins, dark finlets, and white posterior margin of the caudal fin.

An albacore tuna.

5 – Skipjack Tuna (Katsuwonus pelamis): Although not belonging to the same genus as the previous ones, this species is worth mentioning for its popularity in the Portuguese islands and the canned tuna industry in general. It is characterized by its smaller size, dark back, horizontal dark stripes on its belly, 14 to 16 hard rays on its 1st dorsal fin, and lack of scales.

A skipjack tuna.


Fishing Techniques in the ‘Tuna World’:

Tuna fishing is carried out using the following techniques:

  • Longline: This is a type of line fishing method, consisting of a long main line from which several shorter lines, with hooks at the end of each, depend at regular intervals. Floats (buoys) and weights (e.g., lead or stones) responsible for the buoyancy and sinking of the system are also part of this system. This type of fishing is ideal for capturing fish that inhabit deeper zones, such as the Albacore, Bigeye, and Yellowfin. 9% of globally caught tuna is captured using this method. As the average rate of bycatch by this method is 20%, mitigation measures have been taken to prevent the bycatch of marine life.

A pictogram showing how is the longline fishing,

  • Pole and Line: In this method, tunas are caught one by one using a hook attached to a line, which in its turn, is attached to a pole. The fishermen then use the technique of “jump”, which involves pulling the fish on board with a single motion, making it jump. This is a method used worldwide, representing 8% of the global tuna catch. The largest producers of Pole and Line are Japan (100,000 tons), Indonesia (90,000 tons), and the Maldives (76,000 tons). In terms of species preservation, this method is better as it reduces the bycatch of sharks, turtles, and other larger marine animals. This is the technique used by tuna fishermen from the Portuguese islands, Azores, and Madeira.

A pictogram showing how is the pole and line fishing.

  • Trolling: This fishing technique involves several lines with hooks being trailed behind the fishing vessel. This type of fishing represents 2% of the total global tuna catches. Although data is limited, it is believed that trolling has a low percentage of bycatch.

A pictogram showing how the trolling fishing is done.

  • Gillnets: This is the most commonly used method in the Indian Ocean. It involves setting up equipment consisting of one, two, or three walls of net, anchored to the ocean floor or left drifting, free or attached to the fishing vessel. This method represents 4% of the total global tuna catches, but 30 to 40% of the catches are attributed to gillnets in the Indian Ocean, according to the Indian Ocean Tuna Commission (IOTC). Despite the complexity of data analysis, a recent study concluded that bycatch caused by this type of fishing is high. Gillnets are responsible for 64% of shark catches, according to the IOTC. It is also believed that the high mortality of turtles in the Indian Ocean is due to this method.

A pictogram showing how fishing with gillnets is done.

  • Purse Seine: As the name suggests, this technique involves encircling a school of tuna using a large net. This fishing method is consistent and efficient, allowing for the capture of large quantities of fish. This is the most used method, representing 66% of the total global catches. This fishing method, when used on freely swimming schools, has a bycatch rate of 1%. However, when used with fish aggregation devices, its bycatch rate ranges from 1% in the eastern Pacific Ocean to almost 9.5% in the Atlantic Ocean.

A pictogram showing how to fish with a Purse seine.

in “https://www.iss-foundation.org/stocks-and-management/fishing-methods/


Nutrition – Discover the Nutritional Treasure of the Seas:

Tuna is a highly nutritious food. An excellent source of lean protein, omega-3 fatty acids, and a variety of essential vitamins and minerals such as selenium, iron, magnesium, potassium, phosphorus, sodium, B-complex vitamins, niacin, B1, B6, and B12.

A table of contents showing some nutricional values of tuna.

The effects of these nutrients on our body are as follows:

  • Omega-3 fatty acids: Act on cardiovascular health;
  • Iron: Essential nutrient for oxygen transport and red blood cell formation, energy production, and strengthening the immune system;
  • Phosphorus and Magnesium: Minerals necessary for bone and teeth health and proper immune system function;
  • Selenium: Prevention of chronic diseases;
  • Sodium (more present in canned tuna): Functioning of muscle contractions, nerve impulses, and water balance in the body;
  • Niacin: Healthy growth and development;
  • Vitamin B6: Proper functioning of the immune system.
  • Vitamin B12: Proper functioning of nerve cells and the neurological system and production of red blood cells and bone tissue cells;
in “https://saboreiaavida.nestle.pt/bem-estar/


Types of Cuts – Unveiling Some of the Various Types:

Tuna can be cut in various ways, depending on the desired culinary preparation. Some of the most common cuts include:

  • Sashimi: Thin slices of raw tuna, often served with soy sauce and wasabi, highlighting the texture and fresh flavor of the fish.
  • Fillet: Large cuts of tuna meat, ideal for grilling, baking, or oven preparation.
  • Loin: A noble section of tuna, valued for its soft and juicy meat, often grilled or quickly seared to maintain its delicate texture.

As for the cuts practiced by our company, they include:

  • Japanese cut, Loin with fishbone and blood, Loin with skin, Clean loin, Belly, Flitch, Steaks, Skin-on big piece with fishbone and blood, Clean big piece, and Small pieces.

Check out the cuts we have available for each species of tuna: Bigeye, Yellowfin, Bluefin, Albacore, and Skipjack.

A woman cutting up a bigeye tuna.


If you want suggestions on how to prepare your tuna, visit our recipes.


In conclusion, tuna is a versatile and nutritious fish, appreciated for its tasty flesh and is widely used in global cuisine.

If you’re looking to purchase some quality tuna, look no further and contact us!