Many of us like eating tuna, it’s a tasty versatile fish that goes well on a jacket potato, or in a pasta bake… But few people know much about this morsel beyond it’s taste and canned convenience.  In this article I’m taking a deep-dive to understand the challenges faced by the humble tuna, exploring how they almost met their watery end… We’ll also ‘dive in’ to look at the true cost of tuna for people and the planet, before sharing some good news about efforts for their preservation, including what you can do to help out. But first lets get in “tune” and start with what make tuna so ‘cool’…

What Tuna?

There are 15 main species of tuna, but the ones we usually find on our supermarket shelves are yellowfin or skipjack mostly due to their abundance. Bluefin tuna are the Rolls-Royce of the tuna world which also makes them one of the most targeted. These powerful muscular fish have few natural predators as they can swim at speeds of up to 43 mph, making them faster than a great white shark or a killer whale!  They can also regulate their body temperature. This means they can live in subarctic latitudes but not become sluggish in the cooler temperatures. This means they can use that  super fast acceleration to outmatch their prey. Sounds pretty ‘cool’, right?!  However, despite these nifty skills, there is one species in particular that is able to  relentlessly hunt tuna… You guessed it, us humans.

Tuna Challenges

To know how sustainable the tuna you eat is, it’s important to know how they were caught. The most popular methods of fishing include the use of purse seine nets (a large net that is used to surround a school of fish), and longlines (literally a very long line, which can be up to 60 miles long, with tens of thousands of hooks with bait on). These two techniques are pretty indiscriminate. Longlines are the main reason global albatross populations are in decline and purse seine nets are a core contributor to the tens of millions of sharks killed each year. However, there is arguably a more sustainable method of fishing tuna, pole and line fishing. Largely a manual method, it consists of literally a pole and line with a hook attached. Understandably, this technique results in very little bycatch of other species.

The true cost of fish

Regrettably, there is still something fishy going on… In 2019, as part of an advertising stunt, the most expensive tuna in the world sold for a whopping £2.5 million at the Tokyo fish market. Marketing stunts aside, the global desire for tuna and bluefin tuna in particular, is such that the highest grade tuna still retails for ~£144 a kilo. This makes it 7 times more expensive than lobster. Even if we aren’t dining in the finest sushi restaurants or sashimi bars, the ‘true cost’ of a greater ‘spotted’ canned tuna is far more than the £1.06 it can retail for currently.

Each year tens of thousands of tonnes of bycatch from the tuna fishery are discarded. The most wasteful practice of purse seine fishing with Fish Aggregating Devices (FADs) relies on fishes natural instinct to seek shelter under floating rafts or marine debris. Deploying FADs, then subsequently bagging up any and all species that have sought refuge around them results in staggering numbers of turtles and dolphins being caught and subsequently dying each year from the practice.

Numbers are hard to pinpoint, but as much as 53-89% of purse seine tuna fishing, involves the use of FADs. Sadly, most of the worlds canned tuna comes from purse seine caught fish. Understandably, it is one of the most efficient and possibly also the most advanced form of wild capture fishing. And that’s what keeps the price at £1.06 a can. 

Ok ok thats really bad, but can I ever eat a tuna mayo baguette with a guilt-free conscience?

Supermarkets, and food companies are increasingly making changes to source more sustainable options. This is driven in most part by the desires of us, the consumers! If you have ever noticed on the side of a tuna can the “dolphin safe”, or “FAD free” logo, then in theory, that tuna has been caught without the use of these devices. Checks, such as those carried out by NGO OceanMind, track some of these fishing vessels when they are out at sea. Using satellites to monitor their activities it is possible to add independent verification that FADs were likely not used, which can serve to increase consumer confidence.

This means we can buy those products knowing that we are sourcing from a more environmental fishery. That said, the only truly sustainable method is to eat less tuna.

CASE STUDY ALERT! Atlantic Bluefin Tuna: from Bust to Boom

As a result of high demand and intensive overfishing (often using damaging fish methods described above), tuna around the UK and much of those in the Atlantic declined in the 20th century. This continued into the 21st century and by 2007 an estimated 60,000 tonnes of Atlantic bluefin tuna were being caught annually. This was more than double the permitted catch. By 2009, the situation was so bad that the fish was listed as ‘endangered’. This overexploitation had drastic effects on the Atlantic bluefin tuna, modifying not only their abundance but their behaviour and life-history traits.  

But all was not lost! With the species on the verge of collapse, a drastic recovery plan was required, with binding agreements for all Atlantic bluefin tuna fishing nations. Strict regulations were put in place to limit the fishing quotas (amount of fish countries can catch) in an attempt to promote a recovery. Additional conservation methods including deployment of observers onboard fishing vessels and unique certificates to track each fish once caught, helped to reduce the illegal trade and restrict the quantity that could be legally caught.

With these methods, the bluefin tuna fishery started to see a partial recovery and fishing quotas were increased in 2015. Following strict management and engagement from the fishing industry, stocks further improved and in 2021 the extinction status of the Atlantic bluefin tuna was moved from ‘endangered’ to ‘least concern’. This story of recovery for the bluefin tuna species demonstrates the potential for many other species to recover if governments work together with scientists to implement legally-binding strategies.

Be curious!

  • Consider whether you need to buy tuna in the first place, why not buy handline caught mackerel or Cornish hake which are currently more sustainable alternatives or make a tasty veg risotto instead.
  • When shopping for tuna, look out for the ‘FAD free’ and ‘dolphin safe’ logos. And watch out for the less reliable self-declared supermarket label statements.
  • Buy pole and line caught tuna whenever possible. It will state this on the can and most supermarket retailers will stock pole and line caught tuna.
  • Look out for the MSC logo, this certification indicates that the fish has been caught in line with more sustainable practices.
  • Download and use the Marine Conservation Society’s ‘Good Fish Guide’ to check their recommendation on fish before you buy it. They have a great app, with a search function and a traffic light warning system indicating the sustainability of each fish.
  • Look where the fish comes from. On each can lid or base it will indicate which region the tuna was caught. Use the Good Fish Guide to check which areas are listed as the best option for your chosen species of fish.
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