I have to admit that I have been a sushi addict for a long time. There is something about the chilled, clean, refreshing taste of the rice, contrasting with the slightly musky, sweet character of the fish, and the wonderful overtones of the vegetables that sends my taste buds into a world of culinary ecstasy. My favorites are Maki-zushi, Temaki-zushi, and Nigiri-zushi. My absolute favorite sushi fish is eel, but my next favorite is tuna. The succulent, firm meat and delicate flavor blend with the rice and vegetables to create a taste sensation like nothing else can.
The tuna used in sushi is one of two main species: either Pacific Bluefin (Thunnus orientalis) or Yellowfin (Thunnus albacares), with Yellowfin, also known as Ahi, being the preferred fish. The Yellowfin Tuna is a fast-swimming pelagic predator, cruising all the tropical and subtropical oceans of the world in huge schools in search of baitfish, shrimp, and squid. Tuna can maintain a swimming speed of over 25 mph and can achieve bursts of speed in excess of 60 mph, making them one of the fastest moving natural objects in the water. To put this in perspective, that is fast enough to outrun a U.S. Navy Mark 50 torpedo! In fact, tuna can swim so fast that their tails actually cavitate (create a shock wave in the water) that can be picked up on SONAR. Tuna have a primitive thermal system—not quite warm-blooded, but a transitional mechanism—that allows their muscle energy to generate heat, allowing them to maintain a body temperature greater than that of the surrounding water. This enables them to maintain a higher metabolism and contributes to their incredible performance.
The Fight to Protect Tuna
Although tuna normally stay above 250 feet in depth, above the thermocline, tagged fish have been recorded making occasional dives in excess of 3500 feet deep, undoubtedly to escape predators. Few enemies would be able to pursue them at that depth, but that could have its own dangers, exposing them to attack from deep-water species like Giant Squids. But the odds are in their favor, as a squid would most likely be left in the dust, and few other deep-water predators would be large enough to tackle an adult Yellowfin. These predators would probably end up on the tuna’s menu themselves. All species of tuna are incredibly tough and have few natural enemies other than humans. Large pelagic sharks, such as the Mako and Porbeagles, billfish like Marlin and Swordfish, and toothed whales such as the Orca, dolphins, and porpoises are about the only creatures large enough and fast enough to catch them. Left on their own, tuna would flourish. Unfortunately, humans have other plans for them.
The popularity of tuna, combined with human greed, has created a horrific situation. Fishing fleets have increased exponentially in size over the last 30 years, and the world’s population of fish is being decimated by overfishing. The United Nations Food and Agriculture Organization (FAO), made up of some of the top experts in the world, publishes a report every two years. In 2009, they stated that:
- 52% of the world’s ocean fish species are fully exploited.
- 20% are moderately exploited.
- 17% are over-exploited.
- 7% are completely depleted.
- 1% are recovering from depletion.
It doesn’t look so bad on paper, until you realize what these figures really mean. “Fully exploited” means the species are being depleted at the very maximum level that can be sustained under ideal conditions. These would be considered “borderline.” “Moderately exploited” means the fish are being harvested at a level well below what can be sustained. “Over-exploited” means that these species are being depleted at a rate well in excess of what can be sustained and will rapidly become extinct if measures are not taken quickly. “Recovering” means that the species has suffered greatly but is making a comeback. Tuna are one of the main species in the “over-exploited” category. Thanks to Starkist, Bumblebee, and Chicken Of The Sea, poor Charlie Tuna is having a rough time these days. Starkist would probably accept him now.
The three main species used for sushi and sashimi are Yellowfin, Bluefin, and to a lesser extent, the Bigeye Tuna. The commercial industry for tuna began in the 1950s, but in little more than 60 years, the annual harvest rate has increased from 550,000 tons in 1960 to over 4 million tons in 2009. The tuna populations are so overfished that catches are now starting to drop significantly. In the Mediterranean, it is estimated that the Bluefin Tuna will be extinct within 3 years if fishing is not halted. The International Union for Conservation of Nature (IUCN) has listed the Bluefin Tuna as a critically endangered species worldwide, and management by National and International regulatory commissions is considered an international disgrace. Yellowfin Tuna are not faring much better, with catches down by 30% in 2009. As Bluefin populations became depleted, attention shifted to the Bigeye Tuna in 1980. By 2004, catches had dropped to below 50%.
On the other side of the coin, regulating overfishing is a very difficult problem. Pelagic species do not recognize borders or territorial waters and are mostly within international waters, so no one country can enact regulations that would apply everywhere. That leaves us with only international agreements and treaties, but as any Native American can tell you, they are only good if both parties adhere to them. The only other body that could do anything is the UN, and they have been trying to come up with international accords that everyone can live with. It’s just very difficult to get all the countries to agree to anything. There is also the issue of pirate fishing, which is a growing problem. These are fishing fleets that do not report their catches or follow quotas, as required by international law, and often violate territorial waters as they please. So far, they are mainly based in Las Palmas, Spain, but they will undoubtedly expand if measures are not taken to curb their despicable activities.
The problem goes much deeper than just the tuna. The ocean is an ecosystem of which tuna are a vital part. If tuna disappear, the whole ecosystem will collapse, including dolphins, sharks, toothed whales, and all the things that tuna prey on. These species will overpopulate, and eventually, the seas will become devoid of most life. Also, there is the economic impact. Hundreds of thousands of people worldwide depend on fishing for their livelihoods. A good case study is Newfoundland, Canada, at one time one of the world’s premier cod fisheries. Due to overfishing and mismanagement, the cod stocks were completely depleted. In 1992, a moratorium on cod fishing was enacted, but it was too little, too late. The cod still have not returned, and over 35,000 people in over 400 communities remain unemployed. The area has shown no signs of economic recovery, yet.
How You Can Help
Is your piece of sushi destroying the oceans? Absolutely not. There is no need for you to feel guilty about having some sushi or a tuna salad sandwich, for that matter. Boycotting the industry will not help. It is not your job as a consumer to regulate the industry. But here is what you can do to help: Support the appropriate conservation organizations with your donations, and take your elected officials to task. Hold them responsible and accountable for their inaction. Your vote is a very powerful motivator, and if you don’t vote… shame on you! You are part of the problem.
On an international level, if the U.S. is going to continue spending our money and resources as part of the UN, then we need to demand that the UN grow some teeth and stop being so ineffective. They have the cooperation of some of the most powerful military forces the world has ever known (like the U.S. Marine Corps… Oooogh Rah!), and can certainly enforce any international laws they enact. They need to set annual catch limits, prohibit fishing during spawning seasons and in spawning grounds, create a Naval Enforcement Task Force to inspect fishing boats, arrest pirates and other violators, and try them in the World Court. They should hold the countries that support them responsible as well, making them pay for the costs of prosecution and enforcement. They need to ban fishing in depleted areas. This can be done without violating anyone’s sovereignty. If you are in international waters, you are subject to international law, plain and simple. In territorial waters, the countries need to vigorously enforce the laws with their own Coast Guards and navies.
This is the 21st century, and the world is much smaller than it was even just 50 years ago. We cannot allow all countries to do as they please any longer because it affects the whole planet now. We’re all going to have to start working together to make this planet sustainable for everyone. And the time to start is now.
