当前的问题 & 可持续的渔业
You may have seen a new Consumer Reports that tested 5 name brand cans of tuna and found unpredictable spikes in the amount of mercury among all of them. 这一点也不使我吃惊 他们测试的品牌中没有一个是罐装美国捕获的长鳍金枪鱼. So what’s the difference between tuna caught overseas and the tuna caught in the US? The age of the tuna has everything to do with how much mercury the fish has accumulated: the younger the fish, 汞含量越少. 让我解释一下:
汞是金枪鱼的一个问题是因为它们可以活到16年. So if you eat a 16 year old tuna, you are ingesting 16 years of mercury build up into your system. 这可不太好.
金枪鱼在5岁左右成熟之前, they swim closer to the surface of the water where they can be caught with hook and line sustainable fishing methods (this is how we catch them in 俄勒冈州). Albacore that are older than 5 years old swim much farther down to the the bottom, 他们在哪里被网捕获.
Not only are we catching ONLY the young tuna (under 5 years old) this is one of the most sustainable fishing methods in the world: No other species are caught using this method. 这是 how we can ensure we are only catching and canning the young tuna that are so much lower in mercury as to not be of concern.
Major brands are offering tuna that’s caught and canned overseas, mainly in the South Pacific. 这些通常是用渔网捕获的老金枪鱼. Here in 俄勒冈州 we are just in the right place at the right time: every summer Albacore migrate past our coastline, 我们的渔民在哪里捕捉游得离水面更近的幼鱼, 一次一个.
We regularly test our Albacore for mercury and have found it to be consistently 10x lower than the “legal limit” set by the FDA (test results can be found on our website). 这意味着你可以随心所欲地吃俄勒冈长鳍金枪鱼而不用担心. And don’t forget: the health benefits of eating fish and fish oil are incredibly important for good health and longevity!
Mercury is a natural element found in minute quantities in air, water, and all living things. 汞可以通过许多渠道进入食物来源, 包括自然回收, 燃烧化石燃料, 和污染. There has been increased concern about mercury in seafoods since the fall of 2002. 最近，美国.S. Food and Drug Administration (FDA) announced that it will be developing a new advisory on mercury for children and for women who are pregnant, 护理, 或者考虑怀孕. Several other organizations have issued warnings that fish such as tuna should not be consumed by this subset of the population. These warnings have caused unwarranted alarm about all seafoods and general confusion about what is safe to eat or not—and, 在零售商, 当客户询问时该怎么回答. 希望这份情况介绍将填补一些信息空白.
汞在自然界中以无机和有机两种形式存在. 我们关心的是有机汞甲基汞. 甲基汞与组织结合，是鱼类中发现的形式. 有些鱼比其他鱼含有更多的甲基汞, 这取决于它们的水生环境和它们在食物链中的位置. Fish absorb mercury in their gills from their environment and from their food sources as they feed on other aquatic organisms. 一般的经验法则是，鱼越大, 肉中甲基汞的含量越高. A very large 蓝鳍金枪鱼 tuna or 剑鱼 will tend to have larger levels as the compound accumulates.
Although all fish have trace amounts of methylmercury, most fish have less than 0.百万分之一(ppm). 加拿大和美国.S. have established guide-lines for allowable levels of mercury content in fish and seafood products. 美国.S. 极限是1.而加拿大卫生指导方针允许的含量较低，为0.99 ppm.5 ppm. 研究表明，鲨鱼体内的汞含量最高, 剑鱼, 方头鱼, 还有鲭鱼王.
金枪鱼问题是一个复杂的问题. There is research showing that some large tunas, such as 蓝鳍金枪鱼, can exceed the FDA limits. 部分困惑在于, 在过去, 许多报告的结果将所有的金枪鱼列在一起, 不分种类的(长鳍鱼), skip-jack, 蓝鳍金枪鱼, 黄鳍金枪鱼, 等等). One can see tables in general publications such as Newsweek showing fresh-frozen tuna having 0.32 ppm，不同物种之间没有区别. 数据中的范围通常非常宽，例如，从0开始.05 to 1.30 ppm, but it is not possible to differentiate between the species the way the data are reported. 因此, 特定的渔业, 比如用巨魔捕获的西海岸长鳍鱼, is unfairly associated with other tuna species that might have higher levels of mercury. 例如, a recent FDA study showed that canned albacore from common commercial brands had a higher average than canned "light" tuna. 这是, 在某种程度上, 因为普通品牌的长鳍鱼是在开阔的太平洋捕获的较大的鱼, 而“轻”金枪鱼通常是体型较小的鲣鱼.
The good news is that several species in the Pacific Northwest have been shown to have low mercury levels. Research work with troll-caught West Coast albacore showed levels below FDA and Cana-dian guidelines, which makes sense since coastal troll-caught albacore is small (10 to 24 pounds) compared to other commercially caught tunas. 鲑鱼的汞含量很低，沙丁鱼、比目鱼、虾和牡蛎也是如此. There are ongoing research projects to better define the amounts of mercury in fish and determine mercury levels of many of the species off the Pacific Northwest and differ-ences that might occur in size and location.
那么，你怎么跟你的顾客说呢? 适用于儿童和育龄妇女, the FDA advisory will most likely state that it is safe to eat fish and shellfish twice a week and that one should always eat a variety of species. 有些种类，如鲨鱼和旗鱼，应该避免食用. 买卖当地捕捞的鲑鱼, 虾, 比目鱼, 牡蛎是一种简单的选择，几乎没有汞的问题. Troll-caught albacore is safe under these guidelines and there is also good evidence that eating these species is very beneficial to our health. 它们富含omega-3脂肪酸, and a diet of fish high in omega-3s has been shown to reduce the incidence of cardiovascular disease, 改善心理健康, 并提供其他健康福利. 所以尽情享用吧, 少吃蓝鳍金枪鱼寿司, and remember that fish is a nutritious food that confers numerous health benefits as well as tasting great.
本文作者:Michael Morrissey, 俄勒冈州阿斯托里亚俄勒冈州立大学海鲜实验室主任兼教授.
金枪鱼插图由Herb goblrsch绘制. (illustration omitted from this accessible document; it may be found in the printable .pdf版本)
2004年由俄勒冈州立大学出版. oresu - g - 04 - 003
We get a lot of calls about just how low the mercury levels are in our fish: "You say its low mercury, 但证据在哪里呢?" Until now, we've been sending our mercury analysis data to our customers along with their orders. 现在您可以下载 汞分析报告 (PDF, 128K)，并亲自查看!
Updated albacore testing results can also be found on the American Albacore Fishing Association website - www.americanalbacore.com