飼養(yǎng)牡蠣(Raising Oysters)

　　飼養(yǎng)牡蠣

　　過(guò)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(guò)移植來(lái)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(huì)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(huì)呆在那兒并逐漸長(zhǎng)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(zhǎng)越大。不久之后，農(nóng)夫?qū)⑦@些小牡蠣收

　　集起來(lái)，把它們移種進(jìn)其他的水域加快其生長(zhǎng)，然后再次將它們移種進(jìn)另外的水域以使其肥壯起來(lái)。直到最近，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(gè)問(wèn)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(shí)到如果不采取新的措施，牡蠣將會(huì)滅絕或至少會(huì)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(chǎng)所并開始工作。但是他

　　們尚沒(méi)有適當(dāng)?shù)难b置或技術(shù)來(lái)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(duì)捕食數(shù)百萬(wàn)幼小牡蠣的動(dòng)物天敵也所知無(wú)幾。

　　他們失敗了，但他們頑強(qiáng)地堅(jiān)持了下來(lái)。

　　終于，在20世紀(jì)40年代，一個(gè)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(lái)他們發(fā)展了一項(xiàng)技術(shù)來(lái)喂養(yǎng)幼貝至其長(zhǎng)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(zhǎng)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(zhǎng)。此外，這些培殖出的牡蠣口感更佳!

　　raising oystersin the 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 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!