Wild-Caught vs Canned Tuna: Carbon Footprint Compared

Overview

Tuna is one of the most widely consumed seafood products globally, but its journey from the ocean to your plate varies significantly depending on how it reaches you. When we compare "wild-caught tuna" (typically referring to fresh or frozen steaks sold at a fishmonger or grocery counter) against "canned tuna," we are looking at two very different supply chains.

While both start in the ocean, the processing, packaging, and preservation methods create a distinct carbon divide. Canned tuna is often perceived as a budget staple, but from a carbon perspective, it carries the weight of industrial processing and metal production. Fresh wild-caught tuna, while often more expensive, avoids the heavy industrial canning process but faces its own hurdles in the form of high-speed transport and refrigeration.

The Numbers

The carbon footprint of tuna is primarily driven by the fuel used during the fishing voyage and the secondary processing. On average, the emissions for tuna break down as follows:

• Wild-Caught Fresh Tuna: Approximately 2.0 kg to 3.5 kg CO2e per kg. This figure represents the fuel used by fishing vessels (mostly purse seine or longline) and the emissions from cold-chain logistics.
• Canned Tuna: Approximately 5.0 kg to 6.1 kg CO2e per kg. This higher figure accounts for the energy-intensive process of cooking the fish twice (pre-cooking and sterilization), the manufacturing of aluminum or steel cans, and the additional ingredients like sunflower oil or brine.

While fresh tuna can sometimes have a higher footprint if it is air-freighted across continents, canned tuna almost always has a higher "embodied" energy because of the packaging and secondary processing steps.

Why the Difference?

The disparity between these two products comes down to three main factors: packaging, processing, and the "yield" of the fish.

1. The Heavy Toll of Packaging

The most significant difference lies in the can itself. Steel and aluminum production are energy-intensive industries. Creating a tin can requires mining, smelting, and manufacturing, all of which release substantial CO2. In contrast, fresh wild-caught tuna is often sold with minimal plastic wrap or directly from a service counter, significantly reducing the "material" footprint of the meal.

2. Double-Cooking and Sterilization

Canned tuna isn't just raw fish in a jar. It typically undergoes a "double-cook" process. First, the whole fish is steamed to make the meat easier to remove from the bone. Once put into cans with oil or water, it is sealed and heated again in a retort (a giant pressure cooker) to ensure it is shelf-stable and safe from bacteria. This secondary heating phase requires a constant supply of high-temperature steam, usually powered by natural gas or electricity.

3. Supply Chain and Waste

Fresh tuna has a shorter shelf life, which puts pressure on the supply chain to be efficient. However, canned tuna involves more additives. If you buy tuna in sunflower oil, you must also account for the carbon footprint of the oil production (land use, fertilizers, and pressing). Furthermore, the industrial processing of canned tuna often results in a lower "recovery rate" of the meat compared to a whole steak, meaning more raw fish is needed to produce one kilogram of the finished, canned product.

4. Fishing Methods

It is important to note that the way the fish is caught matters more than the packaging in some cases. Pole-and-line fishing is the gold standard for sustainability and low carbon, as it uses less fuel than large trawlers or purse seiners that use heavy machinery and travel further distances to find schools of fish.

What You Can Do

Choosing the most sustainable tuna requires looking beyond just the label. Here is how you can minimize your impact:

• Prioritize Fresh over Canned: When possible, buy fresh or frozen tuna steaks. You’ll avoid the carbon-heavy canning process and the footprint of metal production.
• Check the Label for "Pole-and-Line": Regardless of whether it's canned or fresh, look for "pole-and-line" or "one-by-one" caught tuna. This method uses significantly less fuel than large-scale industrial netting.
• Mind the Oil: If you do buy canned, choose tuna in brine or water. Vegetable oils add an extra layer of environmental impact through land-use change and industrial refining.
• Recycle the Can: If you use canned tuna, ensure the steel or aluminum can is cleaned and recycled. Using recycled metal reduces the energy required for the next can by up to 95%.

By making small shifts in how you source your protein, you can significantly lower your weekly carbon output.

Curious about how your seafood habits stack up against the rest of your diet? Use our carbon calculator to get a personalized estimate of your daily footprint and find more ways to save.