陳蕙雅思教材 - 雅思閱讀精選 (Raising Oysters)

Raising Oysters

In the past oysters wereraised in much the same way as dirt farmers raised

tomatoes - bytransplanting them.    First, farmersselected the oyster

bed, cleared the bottomof old shells and other debris, then scattered

clean   shells about. Next, they "planted"fertilized oyster eggs, which

within two or three weekshatched into larvae.  The larvae drifteduntil

they attached themselvesto the clean shells on the bottom. There they

remained and in       time grew into baby oysters called seedor spat. The spat

grew larger by drawing inseawater from which they   derivedmicroscopic

particles  of food. Before  long, farmers gathered  the baby oysters,

transplanted  them in other waters to speed up their growth, then

transplanted them oncemore into another body of water to fatten them up.

Until recently the supplyof wild oysters and those crudely farmed were

more than enough tosatisfy 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 backas the early 1900's marine biologists realized

that if new measureswere  not taken, oysters  would become  extinct  or  

at  best a  luxury  food. So  they  set  upwell-equipped hatcheries and

went to work.          But they did not have the properequipment or the skill to

handle the eggs. They didnot know when, what, and how     to feedthe larvae.

And they knew littleabout the predators that attack and eat baby oysters

by the millions. Theyfailed, but they doggedly kept at it. Finally, in the

1940's a significantbreakthrough was made.

The marine biologistsdiscovered 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, andspring. Later they developed a technique for

feeding the    larvae and rearing them to spat. Going stillfurther, they

succeeded in breeding newstrains that were resistant to diseases, grew

faster and larger, andflourished  in  water of different salinities and

temperatures. Inaddition,   the  cultivated oysters tasted better!

飼養牡蠣

過去人們飼養牡蠣的方式很大程度上類似於田地裡的農夫種植蕃茄--通過移植來飼養 它們。

首先，農夫選好牡蠣苗床，清除底部的舊殼和其它雜物，然後四處撒播乾淨的殼。 接 著，他們"栽種"已受精的牡蠣卵。  這些卵在 2～3 周內會孵化成幼貝。

幼貝一直漂流直到 粘在苗床底部乾淨的殼上為止。 它們會呆在那兒並逐漸長成小牡蠣。 我們稱之為種子或貝

苗。 貝苗吸進海水中的微小生物作為食物從而越長越大。 不久之後，農夫將這些小牡蠣收

集起來，把它們移種進其他的水域加快其生長，然後再次將它們移種進另外的水域以使其肥 壯起來。 直到最近，野生的以及人工飼養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。這個問題已經變得如此嚴重以至於一些牡蠣苗床已完全消失。 幸運的是，早在 20

世紀初期海洋生物學家們就意識到如果不採取新的措施，牡蠣將會滅絕 或至少會變為一種奢侈的食品。 因此他們建造了裝備良好的孵卵場所並開始工作。 但是他

們尚沒有適當的裝置或技術來處理牡蠣卵。他們不知道何時、用什麼以及如何餵養幼貝。他 們對捕食數百萬幼小牡蠣的動物天敵也所知無幾。

他們失敗了，但他們頑強地堅持了下來。 終於，在 20 世紀 40 年代，一個重要的突破性的進展產生了。  海洋生物學家發現，升高水

溫能夠誘導牡蠣不僅在夏季也在秋季、冬季和春季裡產卵。  後來他們發展了一項技術來喂 養幼貝至其長成貝苗。  

他們進一步成功地培養出了新的品種，可以抵抗疾病、長得更快、 更大並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!