Scientists in Canada say big ocean fish have almost disappeared from the world since the start of industrial fishing in the nineteen-fifties. The scientists found that population of large fish like tuna; swordfish and cod 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 longline fishing is especially damaging to populations of large fish. This method involves many fishing lines connected to one boat. These wires can be close to one-hundred kilometers long. They hold thousands of sharp metal hooks to catch fish.
Longline 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. The study says longline fishing boats now might 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 of Dalhousie University in Nova Scotia led the study with Boris Worm of Dalhousie and the University of Kiel in Germany. Mister Worm says the destruction could lead to a complete re-organization of ocean life systems. Mister Meyers says the decreased number of large fish is 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(祖先). He says not only are there fewer big fish, they are smaller than those of the past.
American government scientists say even with the best efforts to protect fish populations, decreases are to be expected.
小题1:Where is the passage probably taken from?
A．A story book.
B．A business magazine.
C．An environment report.
D．An economic survey.小题2:Big fish have gradually been disappearing especially because ________.
A．longline fishing method is used
B．sea water is getting polluted
C．mankind destroys the environment
D．governments don’t make the best efforts小题3:Which of the following shows the fact that the populations of large fish have dropped?
A．Today’s “large”fish are smaller than those of the past.
B．Longline boats now might catch fewer fish every one-hundred hooks.
C．Fish even able to reproduce don’t have the chance to live longer.
D．Japanese boats could catch about ten fish for every 100 hooks.小题4:What can be the best title?
A．Discoveries Canadian Scientists Have Made
B．Japanese Fishing Industry
C．Losses of Big Fish
D．Modern Fishing Methods小题5:When did the researchers begin to survey the decreasing of large fish?
A．In the 1960s.
B．In the 1970s.
C．In the 1980s.
D．In the 1990s.