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    Raising Oysters

    In the past oysters were raised in much the same way as dirt farmers raised tomatoes - by transplanting them.    First， farmers selected the oyster bed， cleared the bottom of old shells and other debris， then scattered clean shells about. Next， they "planted" fertilized oyster eggs， which within two or three weeks hatched into larvae. The larvae drifted until they attached themselves to the clean shells on the bottom. There they remained and in time grew into baby oysters called seed or spat. The spat grew larger by drawing in seawater from which they derived microscopic particles  of food. Before  long， farmers gathered  the  baby oysters， transplanted  them in  other waters to speed up their growth， then transplanted them once more into another body of water to fatten them up. Until recently the supply of wild oysters and those crudely farmed were more than enough to satisfy people's needs.But  today the delectable seafood is  no longer available in abundance. The  problem has become so serious that some oyster beds have vanished entirely. Fortunately， as far back as the early 1900's marine biologists realized that if new measures were  not  taken， oysters  would  become  extinct  or  at  best  a  luxury  food.  So  they  set  up well-equipped hatcheries and went to work. But they did not have the proper equipment or the skill to handle the eggs. They did not know when， what， and how to feed the larvae. And they knew little about the predators that attack and eat baby oysters by the millions. They failed， but they doggedly kept at it. Finally， in the 1940's a significant breakthrough was made. The marine biologists discovered that  by raising the  temperature of the water，  they could induce oysters to spawn not only in the summer but also in the fall， winter， and spring. Later they developed a technique for feeding the larvae and rearing them to spat. Going still further， they succeeded in breeding new strains that were resistant to diseases， grew faster and larger， and flourished  in  water of different salinities and temperatures. In addition， the cultivated oysters tasted better！

    全文翻譯：飼養(yǎng)牡蠣

    過去人們飼養(yǎng)牡蠣的方式很大程度上類似于田地里的農(nóng)夫種植蕃茄——通過移植來飼養(yǎng) 它們。 首先，農(nóng)夫選好牡蠣苗床，清除底部的舊殼和其它雜物，然后四處撒播干凈的殼。 接 著，他們"栽種"已受精的牡蠣卵。  這些卵在 2～3 周內(nèi)會孵化成幼貝。  幼貝一直漂流直到 粘在苗床底部干凈的殼上為止。 它們會呆在那兒并逐漸長成小牡蠣。 我們稱之為種子或貝苗。 貝苗吸進(jìn)海水中的微小生物作為食物從而越長越大。 不久之后，農(nóng)夫?qū)⑦@些小牡蠣收 集起來，把它們移種進(jìn)其他的水域加快其生長，然后再次將它們移種進(jìn)另外的水域以使其肥 壯起來。 直到比較近，野生的以及人工飼養(yǎng)的牡蠣完全能夠滿足人們的需要。

    但是今天這種 可口的海味已不再大量存在。這個問題已經(jīng)變得如此嚴(yán)重以至于一些牡蠣苗床已完全消失。 幸運(yùn)的是，早在 20 世紀(jì)初期海洋生物學(xué)家們就意識到如果不采取新的措施，牡蠣將會滅絕 或至少會變?yōu)橐环N奢侈的食品。 因此他們建造了裝備良好的孵卵場所并開始工作。 但是他 們尚沒有適當(dāng)?shù)难b置或技術(shù)來處理牡蠣卵。他們不知道何時(shí)、用什么以及如何喂養(yǎng)幼貝。他 們對捕食數(shù)百萬幼小牡蠣的動物天敵也所知無幾。

    他們失敗了，但他們頑強(qiáng)地堅(jiān)持了下來。 終于，在 20 世紀(jì) 40 年代，一個重要的突破性的進(jìn)展產(chǎn)生了。  海洋生物學(xué)家發(fā)現(xiàn)，升高水 溫能夠誘導(dǎo)牡蠣不僅在夏季也在秋季、冬季和春季里產(chǎn)卵。  后來他們發(fā)展了一項(xiàng)技術(shù)來喂 養(yǎng)幼貝至其長成貝苗。  他們進(jìn)一步成功地培養(yǎng)出了新的品種，可以抵抗疾病、長得更快、 更大并且在不同的鹽度和溫度的水中都能茁壯生長。 此外，這些培殖出的牡蠣口感更佳！