新东方背诵文选 L34 Raising Oysters

（单词翻译）

In the oysters² were raised in much the same way as dirt farmers raised tomatoes- by transplanting them. First, farmers selected the oyster¹ bed, cleared the bottom of old shells and other debris³, then scattered⁴ clean shells about. Next, they "planted" fertilized⁵ oyster eggs, which within two or three weeks hatched into larvae⁶. 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 spat⁷. The spat grew larger by drawing in seawater from which they derived⁸ microscopic⁹ particles of food. Before long, farmers gathered the baby oysters, transplanted them once more into another body of water to fatten¹⁰ 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 delectable¹¹ seafood¹² is no longer available in abundance. The problem has become so serious that some oyster beds have vanished entirely¹³.
Fortunately, as far back as the early 1900's marine¹⁴ 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 predators¹⁵ that attack and eat baby oysters by the millions. They failed, but they doggedly¹⁶ 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 spawn¹⁷ 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 resistant¹⁸ to diseases, grew faster and larger, and flourished in water of different salinities and temperatures. In addition, the cultivated oysters tasted better!