The journey from ocean to can involves various fishing methods, each with distinct impacts on marine ecosystems. Understanding how your tuna was caught helps you make choices aligned with your values. Whether you prioritise environmental sustainability, supporting small-scale fishers, or simply want to know what you're eating, this guide provides the knowledge you need.
Commercial tuna fishing has evolved significantly over the past century. While traditional methods like pole and line fishing continue in some regions, large-scale industrial techniques now dominate global production. Let's explore the main methods used to catch the tuna that ends up in Australian cans.
Pole and Line Fishing
Pole and line fishing is the oldest commercial method for catching tuna and remains one of the most sustainable. It works exactly as the name suggests: fishers stand along the edge of a boat, each using a pole with a baited hook to catch tuna one fish at a time.
How It Works
When a school of tuna is located, the boat uses live bait (typically small fish like anchovies) sprayed with water to create a feeding frenzy. As tuna rise to the surface, fishers hook them individually and swing them aboard in a single motion. Skilled pole and line fishers can catch hundreds of fish per hour during an active feeding period.
Environmental Impact
Pole and line fishing has minimal environmental impact compared to other methods. Because fish are caught individually, non-target species (bycatch) can be quickly released if accidentally hooked. There's virtually no risk of catching endangered species like sharks, turtles, or dolphins. The method also tends to catch mature fish rather than juveniles, helping maintain healthy population age structures.
Products specifically labelled "pole and line caught" or "pole caught" indicate this sustainable method was used. Brands like Fish 4 Ever specialise in pole and line tuna.
Limitations
The main limitation is efficiency. Pole and line fishing is labour-intensive and catches less tuna per trip than industrial methods. This makes the fish more expensive and means pole and line operations can only supply a fraction of global demand. The method is also weather-dependent and requires highly skilled fishers.
Purse Seine Fishing
Purse seining is the dominant method for catching skipjack and yellowfin tuna worldwide, supplying approximately 60% of global tuna production. It's the method behind most canned tuna you'll find on Australian supermarket shelves.
How It Works
A purse seine vessel uses a large net that can be up to 2 kilometres long and 200 metres deep. When a school of tuna is spotted, the vessel encircles it with the net. The bottom of the net is then "pursed" or drawn together like a drawstring bag, trapping the fish inside. The entire catch is then hauled aboard.
Free-School Sets vs. FAD Sets
There are two main types of purse seine fishing, with very different environmental implications:
- Free-school sets: The vessel locates and encircles naturally occurring schools of tuna swimming freely in the ocean. This method has lower bycatch rates because free-swimming schools tend to consist primarily of adult tuna.
- FAD sets: The vessel uses Fish Aggregating Devices—floating objects that attract marine life. While FADs increase catch efficiency, they also attract juvenile tuna, sharks, rays, sea turtles, and other species, resulting in significantly higher bycatch.
- FAD sets: Higher bycatch of sharks, rays, turtles; more juvenile tuna caught
- Free-school sets: Lower bycatch; primarily mature tuna caught
- Products labelled "FAD-free" indicate the fish was caught using free-school methods
Environmental Concerns
While purse seining can be conducted responsibly, it poses several environmental risks. FAD fishing in particular has been linked to significant bycatch of vulnerable species. Lost or abandoned FADs (known as "ghost FADs") continue to attract and potentially harm marine life. Some conservation groups advocate for banning FADs altogether, while others push for better FAD management practices.
Longline Fishing
Longline fishing is primarily used to catch larger tuna species like albacore, bigeye, and bluefin. It's less common for the skipjack and yellowfin that dominate Australian canned products.
How It Works
A longline consists of a main line that can stretch for 100 kilometres or more, with thousands of baited hooks attached at regular intervals. The line is set near the surface or at depth depending on target species and left to "soak" for several hours before being retrieved.
Environmental Impact
Longline fishing has significant bycatch issues. Seabirds (including endangered albatrosses), sea turtles, sharks, and marine mammals can all take baited hooks. Various mitigation measures exist, such as bird-scaring lines, circle hooks, and setting lines at night, but effectiveness varies.
Longline-caught tuna is typically sold fresh or frozen as steaks rather than canned, so you're less likely to encounter it in the canned tuna aisle. However, some premium canned products do use longline-caught albacore.
Trolling and Handline Fishing
These methods are similar to pole and line in that they catch fish individually using hooks. Trolling involves dragging baited lines or lures behind a moving boat, while handline fishing uses a single line operated by hand.
Environmental Impact
Both methods have minimal bycatch and environmental impact. They're considered among the most sustainable commercial fishing methods. However, like pole and line, they're less efficient than industrial techniques and can only supply a small portion of the market.
Where You'll Find It
Troll and handline-caught tuna typically commands premium prices and is often found in specialty or gourmet products. Some Australian coastal communities have small-scale troll fisheries that supply local and domestic markets.
How to Identify Fishing Methods on Products
Not all products clearly state their fishing method, but here's what to look for:
- "Pole and line" or "Pole caught": Explicitly indicates this sustainable method
- "FAD-free" or "Free school": Indicates purse seining without FADs
- "Line caught": Could mean trolling, handline, or longline—less specific
- MSC certified: The fishery has been assessed, but doesn't specify method
- No method stated: Likely conventional purse seine (possibly with FADs)
Many brands provide detailed sourcing information on their websites, even if it's not on the can. John West, Sirena, and Safcol all publish information about their fishing methods and sourcing policies online.
Making Sustainable Choices
If sustainability is important to you, here's a practical hierarchy for choosing tuna based on fishing methods:
- Pole and line caught: The gold standard for sustainability
- Troll or handline caught: Equally sustainable, less commonly available
- FAD-free purse seine: Good option with lower bycatch
- MSC certified purse seine: Assessed for sustainability, may or may not use FADs
- Conventional purse seine: Most common, variable environmental impact
Remember that even choosing conventionally caught tuna that's MSC certified represents a step toward supporting better fishing practices. Perfect shouldn't be the enemy of good—any move toward more sustainable choices helps drive industry improvement.
Understanding fishing methods empowers you to make informed decisions that align with your values. Whether you choose premium pole-and-line products or look for FAD-free options within mainstream brands, your choices send market signals that encourage better practices across the industry.