>33 Plankton
    Scattered through the seas of the world are billions of tons of small plants and animals called plankton. Most of these plants and animals are too small for the human eye to see. They drift about lazily with the currents, providing a basic food for many larger animals.
    Plankton has been described as the equivalent of the grasses that grow on the dry land continents, and the comparison is an appropriate one. In potential food value, however, plankton far outweighs that of the land grasses. One scientist has estimated that while grasses of the world produce about 49 billion tons of valuable carbohydrates each year, the sea's plankton generates more than twice as much.
    Despite its enormous food potential, little effect was made until recently to farm plankton as we farm grasses on land. Now marine scientists have at last begun to study this possibility, especially as the sea's resources loom even more important as a means of feeding an expanding world population.
    No one yet has seriously suggested that "planktonburgers" may soon become popular around the world. As a possible farmed supplementary food source, however, plankton is gaining considerable interest among marine scientists.
One type of plankton that seems to have great harvest possibilities is a tiny shrimplike creature called krill. Growing to two or three inches long, krill provide the major food for the great blue whale, the largest animal ever inhabit the Earth. Realizing that this whale may grow to100 feet and weigh 150 tons at maturity, it is not surprising that each one devours more than one ton of krill daily.

    浮游生物
    数十亿吨的被称为"浮游生物"的小动物、植物散布在世界的海洋中。 这些小 的动、植物大多太小而难以被人眼看到。 它们随波逐流，为许多较大的动物提供了基本的 食物。 浮游生物曾被描述为生长在大陆陆地上的各种草类的海洋对应物。 这种比喻是恰当的。 然而就潜在的食物价值而言，浮游生物远胜于草类。 一位科学家曾经估计，世界上的 草类每年生产大约 490 亿吨有用的碳水化合物，而海洋里的浮游生物每年生产的碳水化合物 多于此数的两倍。 尽管浮游生物具备巨大的食物潜能，但直到最近人们还很少象种植草类 那样付出努力养殖浮游生物。 现在，海洋科学家们至少已开始研究这种可能性。 全球人口 不断扩张，海洋资源作为食品的重要性日益突出。 现在还没有人认真说过"浮游生物汉堡" 会很快在世界上流行起来。 然而，作为一种可能养殖的补充性食物资源，浮游生物正引起 了海洋科学家们相当大的兴趣。 一种似乎具有很大收获可能性的微小的虾状浮游生物被称 为鳞虾。 鳞虾长至 2～3 英寸长时即成为地球上曾居住过的最大动物--蓝鲸的主要食物。 成 熟的蓝鲸可以达到 100 英尺长，150 吨重，所以每头鲸每天吞食 1 吨多的鳞虾一点也不让人 吃惊。
>34 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!

    饲养牡蛎
    过去人们饲养牡蛎的方式很大程度上类似于田地里的农夫种植蕃茄--通过移植来饲养 它们。 首先，农夫选好牡蛎苗床，清除底部的旧壳和其它杂物，然后四处撒播干净的壳。 接 着，他们"栽种"已受精的牡蛎卵。 这些卵在 2～3 周内会孵化成幼贝。 幼贝一直漂流直到 粘在苗床底部干净的壳上为止。 它们会呆在那儿并逐渐长成小牡蛎。 我们称之为种子或贝苗。 贝苗吸进海水中的微小生物作为食物从而越长越大。 不久之后，农夫将这些小牡蛎收 集起来，把它们移种进其他的水域加快其生长，然后再次将它们移种进另外的水域以使其肥 壮起来。 直到最近，野生的以及人工饲养的牡蛎完全能够满足人们的需要。 但是今天这种 可口的海味已不再大量存在。这个问题已经变得如此严重以至于一些牡蛎苗床已完全消失。 幸运的是，早在 20 世纪初期海洋生物学家们就意识到如果不采取新的措施，牡蛎将会灭绝 或至少会变为一种奢侈的食品。 因此他们建造了装备良好的孵卵场所并开始工作。 但是他 们尚没有适当的装置或技术来处理牡蛎卵。他们不知道何时、用什么以及如何喂养幼贝。他 们对捕食数百万幼小牡蛎的动物天敌也所知无几。 他们失败了，但他们顽强地坚持了下来。 终于，在 20 世纪 40 年代，一个重要的突破性的进展产生了。 海洋生物学家发现，升高水 温能够诱导牡蛎不仅在夏季也在秋季、冬季和春季里产卵。 后来他们发展了一项技术来喂 养幼贝至其长成贝苗。 他们进一步成功地培养出了新的品种，可以抵抗疾病、长得更快、更大并且在不同的盐度和温度的水中都能茁壮生长.此外，这些培殖出的牡蛎口感更佳!