Question

Blue whales are the largest animals ever known to have existed on the planet, and they can grow to a length of 100 feet and weigh more than 330,000 pounds. But recently researchers have found that these whales are on the move and they have migrated (moved) from California waters to areas off Canada and Alaska for the first time since commercial whaling ended in 1965.

The researchers identified 15 blue whales that have appeared off the coast of British Columbia and the Gulf of Alaska since 1997. Four of these whales were recognized as ones that were once sighted off California shores, suggesting that the whales are returning to an old migration pattern between the coasts.

Before commercial whaling began in the early 1900s, blue whales were found widely throughout the North Pacific and California waters. But from the 1920s to the 1960s, whaling severely reduced the whale populations. Blue whales never recovered in the Northern Pacific, making sightings in this area rare. However, much larger groups of whales have been observed close to California since the 1970s.

The scientists had previously thought that the California population was separate from the population that had historically lived in North Pacific waters. But the current study shows that whales off the coast of British Columbia and the Gulf of Alaska are likely part of the California population.

To identify the blue whales, the researchers looked at photos of cetaceans taken in the North Pacific Ocean and compared them with a library of blue whale pictures taken along the West Coast of the United States and Southern Pacific. Up to now, the researchers are not quite sure why the whales are changing their migration patterns, but they suspect that the whales may be following their food moving farther north by the changes in ocean conditions.

1.According to the passage, blue whales are __________.

A. following the fixed route of migration

B. dying out due to commercial whaling

C. rarely found in the Southern Pacific

D. moving from the south to the north

2.The whale population in the northern Pacific __________.

A. is different from the California population

B. has become the largest group since the 1970s

C. is probably part of the California population

D. has lived there since the 1960s.

3.The underlined word “cetaceans” in Paragraph 5 probably means __________.

A. whales species       B. land creatures

C. ocean conditions     D. migration patterns

4.What might make blue whales migrate according to the researchers?

A. Commercial whaling.     B. Food resources.

C. Weather conditions.     D. Life reproduction.

Answer

1.D

2.C

3.A

4.B

【解析】

试题分析: 本文讲述的蓝鲸的迁徙变化。

1.D 考查细节理解题。根据第一段提到But recently researchers have found that these whales are on the move and they have migrated (moved) from California waters to areas off Canada and Alaska for the first time since commercial whaling ended in 1965.最近研究发现这些蓝鲸从加利福尼亚迁徙到加拿大和阿拉斯加，故选D项。

2.C 考查细节理解题。根据第三段提到blue whales were found widely throughout the North Pacific and California waters. But from the 1920s to the 1960s, whaling severely reduced the whale populations. Blue whales never recovered in the Northern Pacific, making sightings in this area rare蓝鲸在北太平洋和加利福尼亚到处都是但在二十世纪二十年代到六十年代，数量急剧减少，在北太平洋很好看到蓝鲸了，故选C 项。

3.A 考查细节理解题。根据第五段提到为了分析蓝鲸，研究者看了北太平洋的鲸的照片，与美国西海岸的鲸的图书馆的照片进行对比，故选A项。

4.B 考查细节理解题。根据最后一段提到Up to now, the researchers are not quite sure why the whales are changing their migration patterns, but they suspect that the whales may be following their food moving farther north by the changes in ocean conditions直到现在，研究者不确定为什么蓝鲸要改变他的迁徙方式但他们怀疑蓝鲸可能是随着食物的变化而进行流动的，故选B项。

考点 ：科普类阅读。