Most canned tuna comes from skipjack and yellowfin tuna caught in the Pacific, Indian, and Atlantic Oceans, then processed and packed in facilities located primarily in Thailand, Ecuador, Spain, and the United States. The journey from open ocean to grocery shelf involves flash-freezing at sea, shipping to processing plants, cooking, deboning, and sealing in cans or pouches. Understanding which species end up in which products, how they’re caught, and what labels actually mean can help you make better choices at the store.
The Species in the Can
Two species dominate the canned tuna market. Skipjack tuna is the most widely canned fish in the world and the primary ingredient in products labeled “chunk light.” It’s a smaller, fast-growing species that reproduces quickly, which makes it relatively abundant. Yellowfin tuna also goes into chunk light cans, often mixed with skipjack. These two species account for the vast majority of canned tuna globally.
Albacore is the other major player and the only species that can be labeled “white tuna” in the United States. It has a milder flavor, lighter color, and firmer texture than skipjack. Albacore is typically sold as “solid white” or “chunk white” and costs more per can. If a label says “white,” it’s albacore. If it says “light,” it’s almost certainly skipjack, yellowfin, or a blend of the two.
Where the Fish Are Caught
The western and central Pacific Ocean is the largest source of canned tuna by a wide margin. Countries like Papua New Guinea, the Federated States of Micronesia, and other Pacific Island nations host enormous skipjack populations in their waters. The Indian Ocean, particularly around the Maldives and the Seychelles, is another major fishing ground. Yellowfin is caught across tropical waters worldwide, while albacore tends to be harvested in more temperate zones of the Pacific and Atlantic.
After harvest, the fish rarely stay in the country where they were caught. Tuna is a global commodity. Fish caught by Korean or Taiwanese fleets in the Pacific may be processed in Thailand, then shipped to the U.S. or Europe for sale. Thailand is the world’s largest processor and exporter of canned tuna. Ecuador is a major player in the Americas, and Spain leads production in Europe.
How Tuna Gets Caught
Purse seining is the dominant method, responsible for roughly two-thirds of the world’s tuna catch. Commercial boats deploy a massive circular net that surrounds an entire school of fish, then cinch the bottom shut like a drawstring purse. It’s efficient and catches large volumes quickly, but the nets can also trap other marine life, including dolphins, sharks, and sea turtles, depending on the technique used.
Longline fishing uses a main line that can stretch for miles, with hundreds or thousands of baited hooks branching off it. This method catches more albacore and yellowfin and tends to result in higher bycatch of seabirds and sharks. Only about 8% of tuna is caught using pole-and-line methods, where individual fish are hooked one at a time. Pole-and-line fishing produces the least bycatch and is generally considered the most environmentally friendly option, though it’s far less efficient and more labor-intensive.
From Ocean to Can
The processing timeline starts immediately after the catch. Tuna is blast-frozen on the fishing vessel, often within hours of being pulled from the water, dropping the internal temperature rapidly to lock in freshness. The frozen fish is then transported to a processing plant, where it’s sorted by species and size.
At the plant, the tuna is precooked to kill bacteria and make the flesh easier to work with. Workers or machines then clean, debone, and trim the fish. The prepared tuna is packed into cans or pouches along with water, oil, or brine. The sealed containers go through a sterilization step at high temperatures, which is what gives canned tuna its long shelf life, often two to five years. Each batch undergoes quality inspection before shipping to distributors and retail stores.
What “Dolphin Safe” Actually Means
In the eastern tropical Pacific, schools of yellowfin tuna often swim beneath pods of dolphins. Fishermen historically tracked dolphins to find tuna, and purse seine nets set around dolphin pods killed hundreds of thousands of dolphins annually through the 1970s and 1980s. The “dolphin safe” label emerged in response to public outrage over those practices.
In the U.S., NOAA Fisheries runs the Tuna Tracking and Verification Program, the only government-recognized system for certifying dolphin-safe status. Tuna canners must report every shipment they receive, including the species, ocean area of capture, gear type, and dolphin-safe status. All U.S. purse seine vessels fishing in the eastern Pacific with a carrying capacity over 400 short tons must carry an observer from the Inter-American Tropical Tuna Commission on every trip. Imported tuna requires a Fisheries Certificate of Origin declaring its dolphin-safe status for each shipment. The label doesn’t guarantee zero environmental impact, but it does mean specific tracking and verification protocols were followed.
Mercury Differences Between Light and White
All tuna contains some mercury, but the amount varies significantly by species. Light tuna (skipjack and yellowfin) averages about 0.118 parts per million of total mercury. White tuna (albacore) averages 0.407 ppm, roughly three and a half times higher. The difference comes down to biology: albacore is a larger, longer-lived fish that accumulates more mercury over its lifetime through the food chain.
The EPA and FDA joint guidelines recommend eating 2 to 3 servings per week of fish from their “Best Choices” list, which includes light canned tuna. Albacore falls into the “Good Choices” category, with a recommendation of just 1 serving per week. For pregnant or breastfeeding women, the guidance is 8 to 12 ounces of lower-mercury seafood per week. Children should eat 2 smaller servings per week from the Best Choices list. If you eat canned tuna regularly, choosing light over white most of the time is a simple way to keep mercury exposure lower while still getting the protein and omega-3 benefits.
Reading the Label at the Store
A few details on the can tell you a lot about what’s inside and where it came from. “Solid” means the tuna is packed in larger pieces, while “chunk” means smaller, flaked pieces. “In water” versus “in oil” affects both calorie content and flavor but not the source fish. Some brands now print the fishing method (pole-and-line, FAD-free purse seine, or troll-caught) directly on the label, which gives you a clearer picture of environmental impact than the species name alone.
Look for the country of origin and processing location if you want to trace the supply chain. A can might say “Product of Thailand” with tuna caught in the western Pacific. MSC (Marine Stewardship Council) certification indicates the fishery met specific sustainability standards verified by third-party auditors. Not every sustainable product carries the label, since certification is expensive, but its presence is a reliable signal. Between the species, the catch method, and the certification marks, a quick glance at the label can tell you most of what you need to know about where your tuna actually came from.