从文中找出能说明本文主旨大意的中心词：

Big ocean fish have almost been endangered since the start of business fishing in the
1950s. The scientists found that the number of large fish has dropped by 90 percent in the
past fifty years. The study took ten years. The researchers collected records from fishing
businesses and governments around the world. The magazine Nature published(发表)the findings.
The scientists say the common way called longline fishing is especially harmful to large fish. This way includes many fishing lines that are connected(连接) to one boat. If these lines are joined together, they can reach one hundred kilometers. They hold thousands of sharp metal hooks(钩) 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 business fishing can destroy groups of fish much faster than in the
past. It’s not the only worry that the number of large fish is becoming smaller and smaller.
What’s worse, they are smaller in size than their ancestors(祖先). 从文中找出能说明本文主旨大意的中心词： 问一下，这个中心词必须从原文中摘录，不能通过原文编辑吗？比如这篇文章的中心词答：endangered fish, 对吗?

解题思路： 如下
解题过程：
从文中找出能说明本文主旨大意的中心词： business fishing
必须从原文中摘录
全文都在围绕business fishing带来的影响。
有疑问，请留言。
最终答案：略