sample essays of IELTS

34 Raising Oysters

In 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 peoples 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 1900s 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
1940s 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!