More and more fish are being raised on farms before they end up on dinner plates around the world. Aquaculture, or the culturing of fish in a controlled environment, now accounts for 50 percent of the fish consumed globally, a fact that's putting tremendous strain on wild fish.

    The big downside to fish farming: It requires large amounts of feed made from wild fish harvested from the sea.

    There are also concerns about spreading disease from farmed to wild fish.

    Nonetheless, fish farming has grown rapidly in recent years, nearly tripling in volume between 1995 and 2007. Part of the reason for the rise is increased demand for omega-3 fatty acids, a type of fatty acid found in oily fish that is thought to be effective in reducing the risk of cardiovascular disease, according to the National Institutes of Health.

    In order to maximize growth and enhance flavor, aquaculture farms use large quantities of fishmeal and fish oil made from less valuable wild-caught species, including anchoveta （cousins to anchovies） and sardine. In fact, 88 percent of global fish oil consumption goes to aquacultures.

    This adds up to quite a lot of fish being used for fish food. In 2006, about 22 million short tons （20 million metric tons） of wild fish were needed to produce 57 million short tons （51.7 million metric tons） of farmed fish.

    Fishmeal and fish oil are especially important for raising carnivorous fish, including salmon, trout and tuna. "Vegetarian" fish, on the other hand, can be raised on feed made from plants.

    Several legislative acts call for the reduction of fishmeal and fish oil in feeds, including California's Sustainable Oceans Act and the proposed National Offshore Aquaculture Act.

    在世界各地，越来越多的鱼，在它们于餐盘上告罄之前，正在养殖场内不断增加。水产业，或者在一个受控环境进行的鱼的养殖，现在已经占有全球范围内消费 的鱼的 50%.这是一个把巨大压力加到野生鱼类上的事实。

    鱼类养殖的大的消极面是：它需要大量从大海捕获的野生鱼所制成的饲料。

    也担心从饲养的鱼向野生鱼类传播疾病。

    尽管如此，鱼类养殖近年来还是迅速增长，1995 年至 2007 年，在数量上几乎增加三倍。部分原因是对欧米伽-3 脂肪酸的需求增加。根据美国国家卫生研究院的说法，欧米伽-3 脂肪酸是在含油多的鱼类中发现的一种脂肪酸，被认为在降低罹患心血管疾病的风险方面有效。

    为了得到最高的产量并且增强滋味，水产养殖场使用大量的由低价值的野生鱼种，包括秘鲁鳀鱼（凤尾鱼的表亲）和沙丁鱼制成的鱼粉和鱼油。事实上，全球 88% 的鱼油消耗量去往水产养殖。

    这意味着相当多的鱼正被用于鱼饲料。2006年，需要大约 2200 万短吨（2000万公吨）野生鱼来生产 5700 万短吨（5170 万公吨）养殖的鱼。

    鱼粉和鱼油对于饲养食肉性的鱼类，包括鲑鱼、鳟鱼和金枪鱼尤为重要。另一方面，"素食"的鱼，可以用植物做成的饲料来喂养。

    有几个立法法案要求减少饲料中的鱼粉和鱼油，包括加州的《可持续发展的海洋法案》和建议的《全国海洋养殖法案》。