Fishing Practices

As the top fishers of yellowfin and skipjack tuna in the Northeast Tropical Pacific region, we depend on healthy oceans for our livelihoods; and because of that, we understand that fishing is both a privilege and a responsibility. This responsibility means we have a duty to care for our oceans; and that means fishing in a way that protects the marine ecosystem, upon which we depend.


We see this as “ocean-safe” fishing – a way of fishing that ensures healthy oceans for future generations. To do so we:

  • Follow the most rigorous sustainability standards, as set by the international science community;
  • Use the latest in fishing techniques and equipment;
  • Train each of our captains, employees, and staff to be good stewards of the ocean; and perhaps most importantly,
  • Ensure that each of our vessels has an independent scientific observer on board to guarantee compliance with international standards and with our own vision for sustainability.


Commercial fishers utilize five primary techniques for fishing tuna – longline, gillnet, pole and line, purse seine, and troll. Our members fish with purse seine vessels which is the most common commercial technique used around the world. The International Sustainable Seafood Foundation states that purse seine fishing is responsible for about 63% of tuna caught globally every year. Of course, each technique has advantages for the environment and areas of opportunity for improving environmental performance.


Purse seine vessels fish by spotting free-swimming schools of tuna, by spotting tuna swimming in association with dolphins, or by fishing the schools that congregate under natural floating objects (i.e. drifting logs, dead floating animals, kelp beds, floating debris) or man-made objects (floating devices made by man) also known as fish aggregating devices (FADs).

Our members fish free-school tuna and dolphin-associated tuna. Fishing tuna found swimming in association with dolphins is our primary method of fishing. We chose these techniques because they are amongst the most sustainable in the world. Dolphin-associated fishing is the best method for protecting tuna stocks themselves, which is a critical food for large marine mammals and sharks.


For hundreds of years in fisheries around the world fishermen have used the presence of birds and marine mammals as indicators of schools of mature tuna swimming below.  Dolphins associate and swim with mature tuna, adult tuna that have reproduced time and again and have already added to the genetic diversity of the ocean and population. Mexico continues to utilize this method of fishing specifically to protect the ecosystem: the technique protects juvenile and breeding tuna stocks – and has a very low rate of by-catch of critical species – like sharks, rays, and turtles. When regulated under the international Agreement on International Dolphin Conservation Progam (AIDCP) the technique also is one of the safest for marine mammals.

Fishing in association with dolphins and free school fishing are amongst the most sustainable commercial-scale fishing techniques. In addition to protecting marine mammals and tuna stocks, this fishing method – coupled with our aggressive actions on live release of non-target species – is also one of the most protective of sharks, rays, and turtles.

Here is a summary diagram of how we fish:


1. The Heart of Fishing: Vessel and Team

The average tuna vessel is 75 meters long and is staffed by a captain, a 24 person crew, and one independent scientific observer from the Inter-American Tropical Tuna Commission or a comparable certified national program.These independent observers are on each and every fishing expedition, ensuring that our teams always deliver on international scientific standards, mandated operational procedures, and on our own sustainability vision.  Observers pay particular attention to protecting dolphin populations and other marine species.

Lead by our skilled and fully trained teams, vessels can remain at sea for long periods of time: trips typically last from 40 to 60 days.

2. Locating Tuna Schools in a Vast Sea

The geographical area in which we fish is immense – over 14 million square kilometers or about the size of Russia. In such a vast sea, finding schools of mature tuna can be a challenge. We employ several different methods for doing so – ranging from using radar or sonar to sighting through powerful binoculars. In sighting tuna, we look for flocks of sea birds or other sea life that follow the schools of mature tuna.

A critical part of fishing sustainably is to focus on fishing mature tuna, leaving young tuna in the sea to continue reproduction. This method of fishing keeps fish stocks viable.

Helicopters also accompany each expedition, helping our relatively slow-moving vessels to locate and determine the size of the tuna school before dropping a net. These helicopters circle the boat in concentric circles, seeking out signs of tuna. Once we have found a school that can be fished, speed-boats are lowered onto the water to keep the tuna from scattering as the slower moving fishing vessel moves toward the school and the net is dropped into the water.

3. Equipments and Fishing Equipment & Fishing Practices

“Ocean-safe” fishing means that we always strive to use responsible, sustainable practice, and that includes the equipment that we use.

The net of a tuna fishing vessel is almost 2 kilometers long and 190 meters deep. Each net is designed with special safety features that allow non-target species to swim away before the net is hauled on to the boat.

Key safety features in the net that help us protect the ecosystem include 1) special arrangement in the floats of the net to protect species from entanglement. And 2) a special safety panel at the end of the net, known as the “Medina Panel”. The Medina Panel allows non-tuna species to swim clear of the net before it is pulled aboard.

We also employ scuba divers to ensure that all non-tuna species have swum away prior to lifting the net.

4. The Catch

Once we’ve located the right tuna school, a skiff – or small boat – is lowered from the vessel and released.  The skiff carries one end of the net. The vessel continues to navigate with the other end of the net until the skiff and vessel meet again – forming a circle with a diameter of approximately 500 meters. Both the top and the bottom of the net are open at this point.

To close the bottom edge, a steel cable is pulled through rings at the bottom of the net. This creates a “purse” of tuna.  Once the “purse” is formed with the net, our team of highly skilled sailors conducts a back-down maneuver, lowering the net, to release any non-tuna species that are within the circumference of the net.

At this point, the vessel drives forward in an arc – dragging the net and forming an elongated channel.  This is when the Medina Panel and our scuba divers come into the process.  The forward movement of the boat causes water to flow against the “Medina Panel,” pushing it down and dropping the net several meters below the surface.  Any dolphins – that might be within the circumference of the net – swim free.  If necessary, our trained divers assist the dolphins to swim out.

The Mexican industry is most protective industry of dolphins in the world – and that fact can be shown by the data provided by the independent observers on every trip of each of the Alliance’s vessels.

The net remains in the water until all dolphins and other key non-tuna species are released. Divers then conduct a check to confirm dolphins and other key species have all swum free.

Because of our innovative fishing techniques and other intense efforts to protect dolphins and other sea life, the United Nations Food and Agriculture Organization awarded Agreement on the International Dolphin Conservation Program (AIDCP), to which we are signatories, the Margarita Lizárraga Medal, recognizing our commitment to the application of the Code of Conduct for Responsible Fisheries and sustainability.

5. Bringing the Catch on Board

After confirming the release of dolphins and other species, our expert fishing technicians retrieve the net, pulling it toward the vessel with a hydraulic system so that the net closely aligns with the vessel.  Once the net is in place, it is hauled up with a pulley-like landing net, called a brailing net.  The brailing net can carry a great deal of weight – up to 4 tons.

From the moment the net is released until it is towed back aboard the vessel, highly trained fishing experts are involved to ensure that operations are efficient and sustainable – at each step protecting non-tuna species and the larger marine ecosystem.

Our captains and teams take great pride in fishing responsibly on each and every expedition.

6. Tuna, An Important Affordable Protein Source

Once the tuna is hauled aboard, the catch is placed into cold storage tanks which are kept at -12°C for the journey back to port. These storage tanks ensure that consumers have healthy fresh tuna. In Mexico alone, more than 100 million of people depend on tuna as an important protein source.