Whilst having lunch at a local fish restaurant - El Pescador Fish Market in La Jolla – I was surprised and saddened to see Pacific bluefin tuna on the menu and on display. When I pointed this out to my friend, her reply was ‘it’s ok to eat it, I asked the manager and the tuna is line caught locally so its sustainably’. Most people seem to like eating tuna and also consider themselves responsible consumers. But there is confusion about which tuna you can eat and which to avoid eating, what is sustainable tuna, which tuna have the highest mercury levels and what type of fishing methods are most destructive to the health of the oceans. It's hard to make informed choices when the facts are not easy to find or who to believe.
So, does it really matter which tuna you eat?
Yes, it matters for a number of reasons, least of which some species of tuna fish accumulate more toxic mercury in their flesh than others as a result of industrial pollution (coal burning and mining for iron )and that has serious side effects on our health if consumed
There are a number of varieties of tuna – 15 species to be exact - but most people have come across five: bluefin, yellowfin (also referred to as ahi), skipjack, bigeye and albacore. But over the last half century, populations of tuna have declined by an average of 60% with some tuna species now standing on the brink of extinction and, tuna fisheries stand accused of causing devastating bycatch that kills over 80 other species on a daily basis. Basically, we have eaten (and continue to eat) tuna faster than the different species can reproduce.
Bluefin tuna have suffered the greatest declines with Pacific bluefin tuna numbers dropping circa 96%, Southern bluefin by over 90% and Atlantic bluefin, the largest of the three species is now the most endangered of the three species. The main fishing fleets exploiting the stocks are from Japan, Mexico, South Korea and the US, and the high value of the few remaining fish is a further encouragement to fishermen to hunt down the last of the species. A single specimen could make the catchers rich for life, and without rigorous enforcement, there is nothing to stop fishermen pursuing them. Good example was January this year at the Tokyo fish market, it’s reported a restaurant chain paid more than $3m for a giant bluefin tuna.
The way in which tuna is caught is important and sustainable fisheries are those that operate in a socially and economically fair manner. Some fishing methods are extremely destructive and the use of fish aggregation devices (FADs) with purse seine nets will never be sustainable - no matter the species (further information here). The proven environmentally responsible fishing methods include pole & line, trolling, handlines, gillnet and free school (or FAD-free) purse seine net fishing. And sustainable tuna varies by species and method in which it was caught. However, the most sustainable method of catching tuna, when operated according to best practice, is the pole and line method. Each fish is individually caught so it limits the impact on tuna stocks and it’s rare that other species such as turtles or sharks are accidentally caught.
How can we help as consumers?
Check which species of tuna is on offer and ask how it was caught. Make your decision to buy based on the answer or follow general recommendations form conservation organizations. We can all help and make a huge collective difference by choosing sustainable tuna every time we have a choice and that means it needs to meet two requirements:
It must come from a fishery whose practices can be maintained indefinitely without reducing the targeted species’ ability to maintain its population; and
It must be caught without adversely impacting on other species within the ecosystem – including humans – by removing their food source, accidentally killing them, or damaging their physical environment.
But broadly speaking, a good rule of thumb is to choose tuna (both fresh and canned) that is caught by hand-operated pole-and-lines and one of these four species: Pacific Skipjack, Pacific Albacore, Atlantic Albacore and Pacific Yellowfin. Retailers are beginning to respond to consumer demand for sustainable tuna choices and a great example is the food retailer Aldi with their ‘Trace your Tuna’ program!
Keep informed with the Seafood Watch Program
Finally, I’m a huge fan of the work carried out by Monterey Bay Aquarium and their great Seafood Watch Program which gives their recommendations on fish choices, helping both consumers and businesses choose seafood that is fished or farmed in ways that have less impact on the environment. Their SEAFOOD WATCH App is easy to use and, their seafood rating systems is easy and helpful.
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