Tuna

What is tuna?

Tuna is a meaty fish. It belongs to a subgroup of the mackerel family, consisting of 8 species varying in colour and size. Tuna is a nomadic species and can be found throughout the world’s ocean.

Tuna can be eaten fresh or canned. Tuna loin is commonly eaten raw or seared and lightly seasoned, while canned tuna is precooked for a long time and often prepared heavily dressed. 

Tuna facts

• There are five main types of tuna: Skipjack, Albacore, Yellowfin, Bluefin, Bigeye
• Skipjack tuna is the smallest and most abundant of the major commercial tuna species, growing up to around a metre in length
• Yellowfin tuna can grow to more than two metres and weigh close to 200 kilograms
• Almost half of the global tuna catch is caught in the Western Central Pacific Ocean
• Tuna is an extremely large fish. The biggest tuna catch to date was in Aulds Cove off Nova Scotia by Ken Fraser in 1979. It was an Atlantic bluefin, at the record weight and length of 679kg (1,497lb) and 3.7m (12ft). That’s almost as heavy as a truck!
• All the tuna we eat is caught wild from the ocean. Tuna are carnivores at the top of the food chain, so it is vital to look after the whole ocean ecosystem. For a tuna to gain 1 kilo requires roughly 10 kgs of mid-size fish, 100 kilos of small fish, 1000 kilos of small plant-eaters (herbivores such as zooplankton) and 10000 kilograms of phytoplankton.
• Tuna is a global commodity, accounting for more than 8% of the global seafood trade. By 2027, the canned tuna market could be valued at as much as $US 11.89 bn.
• Tropical skipjack can reproduce from about 2 years old and an adult female can spawn as many as 2million eggs daily, and any time of year. Once fertilised, the tiny eggs hatch within a day, floating on the ocean currents as zooplankton. Tuna in cooler waters have a longer lifecycle, for example, albacore tuna in the Indian Ocean, is usually 5-6 years old before reproducing, spawning every 2.2 days from November to January with females releasing as many as 2.6 million eggs.

Main types of tuna

Skipjack

Actually, a related species to tuna grow to a max weight of 35 kg and is commonly purchased as canned tuna.

Albacore

With large pectoral fins, this grows up to 60 kg and is found fresh, in cans and preserved in jars.

Yellowfin

As the name suggests they have bright yellow fins and finlets. You'll find yellowfin fresh as steaks and in cans.

Bluefin

These giant fish grow to be up to 700 kg! Despite this, they're as fast as a car. Bluefin tuna is most commonly found in sashimi and sushi.

Bigeye

These tuna have big eyes and grow to be up to 210 kg. They swim at depths of 500 m and so have a protective layer of fat that makes them the 'white beef' of sashimi.

Is tuna sustainable?

There is no such thing as a sustainable species of fish. Only sustainable populations of fish.

Tuna fisheries can be associated with significant bycatch problems, catching and entangling seabirds, sharks and marine mammals. Different fisheries have vastly different impacts depending on how the fishing gears are used and where the tuna is fished.

Overall, the latest estimates from the UN FAO indicate the global tuna catch in 2019 was 5,768,109 tonnes. As more tuna fisheries make a commitment to sustainability and become certified to the MSC Fisheries Standard for sustainable fishing, a greater proportion of all the tuna caught is engaged in the MSC program.

A report by the UN published in 2020 says between 2014 to 2019 the number of major tuna stocks experiencing overfishing went down from 13 to five. This means eight fish stocks are now being rebuilt to reach a healthy level.

Research by the ISSF shows the current status of each of the major tuna stocks in more detail:

• Skipjack tuna numbers are in great shape in most of the ocean because it is a fast-growing tuna that can reproduce from 2 years old. But it needs careful management to keep it that way.
• Yellowfin in the Indian Ocean are overfished
• Bigeye is overfished in the Atlantic
• The two species of Pacific bluefin tuna are overfished

Each World Tuna Day, the MSC campaigns to accelerate action for sustainable tuna.

Where can I buy sustainable tuna in Australia and New Zealand?

You'll find sustainable tuna with the MSC blue fish tick meaning it comes from a fishery that has been independently assessed to the MSC Fisheries Standard as a well-managed and sustainable fishery.

Learn more about tuna fishing

Worldwide there are 23 stocks of the major commercial tuna species: 5 skipjack, 4 yellowfin, 4 bluefin, 6 albacore, and 4 bigeye stocks. Some of these tuna stocks have healthy numbers and are being managed well, others are not.

There are different ways of catching tuna. The methods and gear used in tuna fishing could depend on: 

• Which tuna species are being fished
• Where the tuna lives 
• The size of the tuna

Common gear types used by MSC certified tuna fisheries include pole and line, purse seine nets and longlines.

Any of these gear types can be used sustainably, depending on their use, the amount of tuna being caught and how their gear affects the wider ecosystem. 

There is also discussion around the sustainability of tuna caught using Fish Aggregating Devices (FADs), which if managed well can also be considered sustainable.

Tuna Australia members operating in the Eastern Tuna and Billfish Fishery now hold MSC certification for albacore, yellowfin, bigeye and swordfish. 

Dolphin-friendly

Most tuna species have nothing to do with dolphins. Yellowfin tuna are associated with dolphins in parts of the Pacific Ocean, where the species often swim close together. 

In these places, dolphins swim near the water surface, with yellowfin tuna up to 150 metres below. The reasons for this flocking behaviour are uncertain and are only observed in older yellowfin tuna. 

Historically, fishers in the Eastern Tropical Pacific near Central America have used the presence of dolphins to find yellowfin tuna. 

Tuna in the Eastern Tropical Pacific is usually caught with purse seine nets, which surround a school of fish before being pulled together. Because dolphins swim above tuna, accidental catch (bycatch) of dolphins has been high in the region.

In 1989, the dolphin bycatch for Mexican purse seine tuna fisheries was 132,000 animals. A new strategy was needed and more selective fishing methods were introduced. Between 1985 and 1997 dolphin mortalities dropped by 99%.

Since 2017, the Northeastern Tropical Pacific Purse Seine yellowfin and skipjack tuna fishery have been MSC certified.

Dolphin safe, or dolphin-friendly labels mean that tuna has come from boats with no interaction with dolphins. These labels don’t provide any reassurance about the wider impacts of tuna fishing.

Whereas the MSC blue fish tick label means that the tuna was caught with consideration for the wider marine environment, including impacts on species such as dolphins.

Most popular sustainable tuna recipes

As well as our delicious sustainable tuna recipes, we've prepared a guide to cooking with sustainable tuna. Our guide to cooking with sustainable tuna guide will help you go that extra mile and know how to get the best out of your yellowfin, your albacore or a $1 tin of skipjack.

Explore more sustainable fish to eat

Find more sustainable seafood species that are MSC certified in Australia and New Zealand.

Explore the sustainable seafood guide.