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，越來(lái)越多的魚，在它們于餐盤上告罄之前，正在養(yǎng)殖場(chǎng)內(nèi)不斷增加。水產(chǎn)業(yè)，或者在一個(gè)受控環(huán)境進(jìn)行的魚的養(yǎng)殖，現(xiàn)在已經(jīng)占有全球范圍內(nèi)消費(fèi) 的魚的 50%.這是一個(gè)把巨大壓力加到野生魚類上的事實(shí)。

    魚類養(yǎng)殖的大的消極面是：它需要大量從大海捕獲的野生魚所制成的飼料。

    也擔(dān)心從飼養(yǎng)的魚向野生魚類傳播疾病。

    盡管如此，魚類養(yǎng)殖近年來(lái)還是迅速增長(zhǎng)，1995 年至 2007 年，在數(shù)量上幾乎增加三倍。部分原因是對(duì)歐米伽-3 脂肪酸的需求增加。根據(jù)美國(guó)國(guó)家衛(wèi)生研究院的說(shuō)法，歐米伽-3 脂肪酸是在含油多的魚類中發(fā)現(xiàn)的一種脂肪酸，被認(rèn)為在降低罹患心血管疾病的風(fēng)險(xiǎn)方面有效。

    為了得到最高的產(chǎn)量并且增強(qiáng)滋味，水產(chǎn)養(yǎng)殖場(chǎng)使用大量的由低價(jià)值的野生魚種，包括秘魯鳀魚（鳳尾魚的表親）和沙丁魚制成的魚粉和魚油。事實(shí)上，全球 88% 的魚油消耗量去往水產(chǎn)養(yǎng)殖。

    這意味著相當(dāng)多的魚正被用于魚飼料。2006年，需要大約 2200 萬(wàn)短噸（2000萬(wàn)公噸）野生魚來(lái)生產(chǎn) 5700 萬(wàn)短噸（5170 萬(wàn)公噸）養(yǎng)殖的魚。

    魚粉和魚油對(duì)于飼養(yǎng)食肉性的魚類，包括鮭魚、鱒魚和金槍魚尤為重要。另一方面，"素食"的魚，可以用植物做成的飼料來(lái)喂養(yǎng)。

    有幾個(gè)立法法案要求減少飼料中的魚粉和魚油，包括加州的《可持續(xù)發(fā)展的海洋法案》和建議的《全國(guó)海洋養(yǎng)殖法案》。