阅读理解。
You may have heard the popular saying, "there are always more fish in the sea". But as many new
studies show, fish populations are changing, and not necessarily for the better.
Consider the case of big, predatory (食肉动物) fish. These giants, like sharks and cod (鳕鱼), eat
other smaller fish. Big fish are an important part of the marine ecosystem (海洋生态系统) because they
keep down the numbers of smaller fish. Without fish that eat other fish, populations of smaller swimmers
would increase, eating more plants, and leaving less vegetation for other creatures, including future fish.
As fierce as predators can be, they're no match for fishing technology. Many people love to catch
predatory fish like sharks, cod and tuna, and new studies suggest that over-fishing is threatening these
creatures near the top of the marine food chain.
In one study, Villy Christensen and his colleagues looked at 200 past studies of marine life to learn
how fish populations have changed over time. Christensen reported that between 1910 and 1970, the
numbers of big predators decreased slowly, and that in 1970 their populations really started to drop.
Around that time, fishing ships began using new tools that led to more fish being caught. The numbers
have been falling quickly ever since.
Reg Watson looked at the problem from the perspective of the fishermen. In the middle of the 20th
century, Watson reported, fishing boats didn't go far from home, and most fish were caught near the
shore. That was no longer true by the 1980s. By then, fishing had moved farther from shore, into the
open oceans, and was helped by the development of new technologies. But since the 1990s, something
has changed. Despite new technologies and more efforts, fishing operations have not continued to
develop.
Scientists study historical data to understand the present, and this research is needed to forecast the
future of fish and fishing. And the forecast doesn't look good: large predator fish are becoming harder to
find, and soon may disappear.
1. From Paragraph 2 we can learn that .
A. more big fish are breeding in the ocean
B. the fewer smaller fish, the more big fish
C. big fish are less important than smaller fish
D. the numbers of smaller fish are controlled by big fish
2. Why did the number of big predators begin to fall quickly in 1970?
A. Fishing ships began using new tools with which they could catch more fish.
B. There were fewer smaller fish than before.
C. There were more people catching big predators.
D. Their environment was being polluted by fishing ships.
3. Which of the following would scientists most probably agree with?
A. It may soon be difficult to find large predator fish.
B. It will cost much more in the future to catch big fish.
C. Smaller fish still give the fishing industry a bright future.
D. It is tough for researchers to forecast the future of fish.
4. What can we conclude from the passage?
A. The decrease of the number of smaller fish has changed the marine food chain.
B. Big fish have to live in the deep sea to avoid being caught.
C. Over-fishing with new technology accounts for the decrease of the number of big fish.
D. The decreasing populations of small fish lead to fewer big fish.
