Swimming with Bluefin Tunas at a Sustainable Tuna Farm

tuna tour in l'ametlla del mar

Putting on a wetsuit is hard– and so is drinking cava on a very shaky catamaran!

But I had set out to challenge myself and learn new things, something I definitely achieved on my Terres de l’Ebre blogger trip after my speaking gig at the 2015 Travel Bloggers Exchange in Costa Brava. I passed over the tempting gastronomy themed trip (which included dining with Michelin star chefs!) in favor of swimming with giant tuna fish, being swarmed by bees, and sailing out to mussel and oyster beds.

It was a food lover’s dream– despite a few moments of second guessing myself.

When I finally got on my wetsuit (which is much harder than it looks), I jumped off the boat and into a large enclosed tuna pool in the middle of the cold Mediterranean Sea.

tuna tour in Catalonia Spain
This was so hard to get on!

Swimming with endangered tunas

When I first learned that our trip involved swimming with endangered bluefin tunas and then eating them, I’ll admit I was a bit alarmed. We were supposed to be exploring eco tourism in the Terres de l’Ebre region– so how was this possible?

Tuna Tour in Spain
Not your average tour!

Bluefin tuna is endangered according the the WWF. This is mainly due to overfishing and illegal fishing, which happens because of the incredible demand for bluefin tuna– above all in Japan where one tuna has sold for nearly 2 million dollars!

But the story of tuna is an integral part of Spanish history and cuisine, something I am often reminded of in Cadiz, where they still fish a small number of tuna every year using the traditional (and sustainable) almadraba methods.

Tuna Tour is a part of the Grup Balfegó, a company that has been fishing in the small village of L’Ametlla del Mar for five generations. The family run business is a leader in sustainability and environmental responsibility, and their tuna tour aims to show visitors how incredible these creatures can be, while also educating them about the history of the bluefin tuna and current situation. During the boat ride you’ll see a video about bluefin tunas, and once you’ve reached the tuna pools (located about 30 minutes off of the coast) you’ll suit up for your swim.

Tuna pools at tuna farms
The enclosed tuna pools

Tuna fishing methods for Grup Balfegó

Based in the small fishing village of L’Ametlla del Mar, Grup Balfegó does things quite differently than other fisheries. They consider themselves one of the world’s leading examples in sustainable fishing methods and leaders in bluefin tuna research.

They fish the wild bluefin tunas from the Balearic Sea, only after they’ve already migrated up from the Atlantic and laid their eggs. Their expert fishermen track down a school of tunas, and position an enormous net over them, driving the boat in a circle to capture them inside.

Once the net is closed, the bluefin tuna begin to realize that their environment has changed, and they search for an exit. But instead of extracting the net from the water, the technique is to keep them alive and swimming, and as calm and happy as possible.

Tuna farms in Spain
Here’s a tuna I spotted from the boat.

Another boat arrives with a transport pool, which is then attached to the ring that the tuna are trapped in. Professional divers with whistles that simulate dolphin radar enter the water and direct the tunas from the initial enclosure to the transport pool, and once one of the tunas crosses over, the rest follow suit. The entire process is recorded on video to ensure precision in tracking exactly how many animals are caught. Only minutes later the video footage is watched with official controllers on board, and the exact numbers are recorded. The documents are signed by inspectors and observers to ensure accuracy.

Getting from the Balearic Sea to L’Ametlla del Mar

The boats travel extremely slowly, at about 2 kilometers an hour, all the way to L’Ametlla del Mar. Here the tunas must be transferred to a fixed pool, where they’ll live until they have fattened up again and are requested for slaughter. The company only slaughters a tuna after they have a buyer lined up.

The tunas arrive very thin, since when they were captured they had just finished their swim up from the Atlantic and laid their eggs– strenuous work! Once they’ve settled in to the new pools, they are starving. Here they’re fed a natural diet of mackerel, sardines, and herring, which is what they would have eaten in the wild. This natural diet ensures the quality of wild tuna, without the cruel fishing practices.

The tuna eat up to 4% of their body weight during the first few weeks in the sea farms, and they’ll remain enclosed for a minimum of four months and up to one year, gaining 15 to 100% their body weight in total.

Balfegó claims to currently be the only company that uses this system, allowing them to provide fresh tuna to clients (and jobs to locals) all year round.

From pool to plate

To get the product from sea to consumer, the tuna are hand picked by a specialist diver to check for weight and fat content. The diver swims gently, trying not to scare them, and forty to fifty fish are extracted daily three times per week.

Grup Balfegó also traces their tuna from when it’s first extracted, with the strong belief that traceability is transparency. From the very beginning their origin, size, weight, documentation, and fat level are electronically recorded. When served Balfegó tuna in some of the best restaurants in the world you’ll receive a bar code that you can scan to learn everything about that tuna’s history.

My experience

The pools are enormous and since you’re only snorkeling you can’t go very deep, but even in murky water caused by the bad weather during our visit, I saw schools of 15-20 tunas pass by beneath my body. They are truly incredible creatures– and enormous at around 200 kilos (though they can grow up to 900 kilos throughout their 40 year lives).

After our snorkeling experience we got back on board for a shower and some sashimi. I proceeded to eat the best tuna sashimi I’ve ever tasted. The tuna belly (ventresca de atún) was unreal, marbled with the most delicious, melt-in-your-mouth fat. But I still had a nagging voice in the back of my head…

tuna tour in Spain
The best tuna sashimi I’ve ever tried!

Should we even be eating bluefin tuna at all?

The simple answer seems to be no.

Given that it’s often difficult to really know where our food comes from these days, there is a strong possibility that when ordering bluefin tuna you are buying something that was not fished in a sustainable way, therefore contributing to the dangerous situation of this incredible fish. If you do want to enjoy this delicacy– do your research. Buy from a company that is acting in accordance with the law and, even better, one like Balfegó, that allows you to learn everything about the tuna on your plate.  

Read on

Read more about Grup Balfegó here

See information about the Tuna Tour here

Check out the best things I ate in my Terres de l’Ebre trip here

Would you go swimming with tuna? And how important is sustainability for you when buying fish?


  1. Lauren-Thanks so much for this post. I was concerned when I read about the trip and know how many activities are green washed these days. It’s good to hear that they are actually working in a sustainable way to maintain the bluefin population. It must have been kind of strange swimming and then eating-all part of the “know your food” cycle I guess. Grup Balfego has a good model that others could follow.

  2. Lauren, are the tuna produced by GRUP BALFEGÓ certified under the Aquaculture Stewardship Council (ASC)? WWF whom you quote in your post was instrumental in founding ASC in 2009. I could find no mention of GRUP BALFEGÓ in the ASC certified farms nor in the farms under assessment.

    1. Hi John, I’m afraid I don’t know– I will try to find out, but perhaps have a look at their website as well, which has a lot of the information about the different initiatives they’re involved in. I know that they have more inspectors than legally required on their boats during the process. I’ll let you know if I receive more information.

      1. They are eating 4% of their body weight per day? Of what? The current state of fish feed is completely unsustainable as it’s comprised of wild-caught fish or fish meal.

        Additionally, bluefin tuna spawn multiple times in their life, so removing large individuals ‘after spawning once’ is hardly favourable.

        The term ‘sustainable’ here has been issued far too easily in the title here, which is very unfortunate. Perhaps this company is moving in the right direction with their various initiatives but that doesn’t mean we should be consuming psuedo-sustainable ranched ocean predators that are ENDANGERED. Would you eat ranched Rhino?

        1. Hi Reece, thanks for your comments. I believe they are fed mackerel and sardines mainly, and I don’t believe these fish have only spawned once– necessarily. I know they have strict quotas and size restrictions so I believe some would have already spawned in previous years. You are totally right that it is a serious issue and we should all educate ourselves before consuming. I wouldn’t eat a ranched Rhino… food for thought.

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