题目内容
Boris Worm of Dalhousie University in Nova Scotia, Canada, led the international team that did the study. Professor Worm says species have recently been disappearing from oceans at increasing speed. At this rate, he says, all seafood species could collapse by 2048 and seafood supplies from the world’s ocean could be almost gone by then.
Other studies have also warned about the dangers of overfishing and the effects on ocean environments. But not everyone thinks the oceans are likely to be empty in fifty years. Some scientists said parts of the world do have problems, but others are doing a good job of protecting fish populations. Government officials in several countries with large fishing industries also questioned the research.
The study appeared earlier this month in Science magazine.
The researchers say damage to oceans affects not only fish populations but also the productivity of ecosystems. These complex systems help control water quality. The scientists say the loss of different kinds of sea life appeared to increase the risk of fish kills and beach closures from harmful algae growth.
The scientists examined the results of thirty-two experiments and observed forty-eight protected areas. They also looked at records of catches worldwide. They studied records from the United Nations Food and Agriculture Organization for nineteen fifty to two thousand three. And they examined archeological information and other historical records for twelve coastal areas. That research reached back over a thousand years.
Boris Worm says the findings were, in his words, "beyond anything we suspected." But he also said the situation is not too late to correct. He said that with good fisheries management, some species could completely recover in three to ten years.
【小题1】Which of the following isn’t the damage to the ocean?
| A．The species of fish in the ocean are reducing. |
| B．Sea water is polluted. |
| C．Sea water quality is improved. |
| D．Less productivity of ecosystem. |
| A．unbearable | B．unbelievable |
| C．doubtful | D．Convincing |
| A．was conducted by scientists from Canada |
| B．referred to information of many countries |
| C．lasted from 1950 to 2003 |
| D．referred to records dating back to over 1,000 years ago. |
| A．It’s too late to take action to improve the situation. |
| B．Some species will recover with efforts. |
| C．Boris Worm hopes that people take the warning serious. |
| D．Boris Worm shows great concern about ecosystem. |
【小题1】C
【小题2】D
【小题3】B
【小题4】A
解析
industrial fishing in the 1950s. The scientists found the populations of large fish like tuna(金枪鱼), swordfish and cod（鳕鱼） have dropped by ninety percent in the past fifty years.
big fish, but also they are smaller than those of the past.
an those of the past.When prehistoric man arrived in new parts of the world, something strong happened to the large animals; they suddenly became extinct. Smaller species survived; the large, slow-growing animals were easy game, and were quickly hunted to extinction.
Now something similar could be happening in the oceans. That the seas are being over-fished has been known for years and researchers such as Ransom Myers and Boris Worm have shown how fast things are changing. They have looked at half a century of data from fisheries around the world. Their methods do not attempt to estimate the actual biomass (the amount of living biological matter) of fish species in particular parts of the ocean, but rather changes in that biomass over time. According to their latest paper published in Nature, the biomass of large predators (animals that kill and eat other animals) inanes fishery is reduced on average by 80% within 15 years of the start of exploitation. In some long-fished areas, it has halved again since then.
Dr. Worm acknowledges that these figures are conservative (保守的). One reason for this is that fishing technology has improved. Today’s vessels can find their prey using satellites and sonar, which were not available 50 years ago. That means a higher proportion of what is in the sea is being caught, so the real difference between present and past is likely to be worse than the one recorded by changes in catch sizes. In the early days, too, longlines would have been more saturated with fish. Some individuals would therefore not have been caught, since baited hooks would have been available to trap them, leading to an underestimate of fish stocks in the past. Furthermore, in the early days of longline fishing, a lot of fish were lost to sharks after they had been hooked. That is no longer a problem, because there are fewer sharks around noise.
Dr. Myers and Dr. Worm argue that their work gives a correct baseline, which future management efforts must take into account. They believe the date support an idea current among marine biologists, that of the “shifting baseline”. The notion is that people have failed to detect the massive changes which have happened in the ocean because they have been looking back only a relatively short time into the past. That matters because theory suggests that the maximum sustainable yield that can be cropped from a fishery comes when the biomass of a target species is about 50% of its original levels. Most fisheries are well below that, which is a bad way to do business.
【小题1】The aim of the extinction of large prehistoric animals is to suggest that _______.
| A．large animal were not easy to survive in the changing environment |
| B．small species survived as large animals disappeared |
| C．large sea animals may face the same threat today. |
| D．Slow-growing fish outlive fast-growing ones |
| A．the stock of large predators in some old fisheries has reduced by 90% |
| B．there are only half as many fisheries are there were 15 years ago |
| C．the catch sizes in new fisheries are only 20% of the original amount |
| D．the number of larger predators dropped faster in new fisheries than in the old |
| A．fishing technology has improved rapidly |
| B．then catch-sizes are actually smaller then recorded |
| C．the marine biomass has suffered a greater loss |
| D．the date collected so far are out of date. |
| A．people should look for a baseline that can’t work for a longer time |
| B．fisheries should keep the yield below 50% of the biomass |
| C．the ocean biomass should restore its original level. |
| D．people should adjust the fishing baseline to changing situation. |
| A．management efficiency |
| B．biomass level |
| C．catch-size limits |
| D．technological application. |
Scientists in Canada say big fish have almost disappeared from the world since the start of
industrial（产业的） fishing in the 1950s. The scientists found the numbers of some kinds of large fish have dropped by ninety percent in the past fifty years.
The study took ten years. The researchers gathered records from fishing businesses and governments around the world. The magazine Nature published the findings.
The scientists say the common method called long line fishing ravages the populations of large fish. This method involves many fishing lines connected to one boat. These wires can be nearly one hundred kilometers long. They hold thousands of sharp metal hooks to catch fish.
Long line fishing is especially common in the Japanese fishing industry. Records showed that Japanese boats used to catch about ten fish for every one hundred hooks. But long line fishing boats now might only catch one fish per hundred hooks.
The scientists say industrial fishing can destroy groups of fish much faster than in the past. The study suggests that whole populations can disappear almost completely from new fishing areas within ten to fifteen years.
Ransom Myers and Boris Worm of Dalhousie University in Nova Scotia led the study with the University of Kiel in Germany. Worm says the destruction could lead to a complete reorganization of ocean life systems. Meyers says the decreased num
bers of large fish are not the only worry. He says even populations that are able to reproduce do not get the chance to live long enough to grow as big as their ancestors. He says not only are there fewer
big fish, but also they are smaller than those of the past.
It’s the end of this program ,Thank you for your listening.
【小题1】What’s the best title for the passage?
| A．Big fish are disappearing | B．Long—line fishing in Japan |
| C．The harm of industrial fishing | D．Stop killing big fish |
| A．Fish can disappear almost completely from new fishing areas. |
| B．Now long—line fishing boats might catch one fish per hundred hooks. |
| C．Fish now don’t have the chance to grow big enough. |
| D．Scientists spent ten years studying the populations of large fish. |
| A．The number of big fish started to drop greatly about fifty years ago. |
| B．The study was started by Boris Worm of Dalhousie alone. |
| C．There will be no big fish left in fifty years . |
| D．Japaneses people have stopped catching big fish. |