Methods by which one fisher uses one line to catch one tuna fish at a time, includes pole-and-line, handline and troll fishing techniques.

Baitfish are caught as a prerequisite to tuna fishing, they are traditionally fished at night in inshore waters using a small lift net or seine net. Baitfish are temporarily stored in sea pens, or transferred to the bait wells within the boat, where they are kept alive to be used during tuna fishing.

Finding a tuna school can take several hours, so the fishers act quickly when one is located. Vessel skippers often pinpoint tuna schools using seabirds or by sighting other fishing boats. Monitored and maintained anchored Fish Aggregating Devices (aFADs) are also used to attract tuna schools, supporting improved fishing efficiency.

On finding a school of tuna, the live baitfish is thrown overboard. This process, known as chumming, is usually carried out in conjunction with water sprinkling, which creates the illusion of a large school of small fish near the water’s surface. The effect sends the tuna into such a frenzy that they bite at shiny, moving object, including the fisher’s lures.

Fishers demonstrate their strength and dexterity with pole-and-line, sometimes working in pairs to fish larger tuna. Catching their targets one-by-one reduces the capture of juvenile tuna and non-target species.

One-by-one fishers log their catch data differently, depending on regulations and available resources, with most using a logbook or digital system to record data on the catch including tonnage, location, and bycatch.

Self-reported data is only part of the story and in Indonesia, efforts are being made to validate and verify this information through third party methods such as independent port sampling, onboard observers and vessel trackers.

Larger vessels store their tuna on capture in a refrigerated hold, while smaller vessels put the fish on ice in the boat hold after the decks have been cleared.

One-by-one fishing requires great strength, skill and perseverance from the fisher. With origins dating back several hundred years, these traditional techniques are regarded as the most socially and environmentally-responsible methods today. Many of the family-owned companies involved in the capture or post harvest processing of tuna fish have been involved in fishing for generations, passing knowledge and adapting to the changing industry.