Whaling began in the 17th century for meat and oil, expanded globally through the 18th-19th centuries, and is now practiced through scientific, commercial, and aboriginal subsistence whaling despite conservation concerns. Overhunting has severely threatened whale populations like the blue and gray whales, though international agreements in the 1930s-1940s and conservation groups aim to curb threats and allow whale numbers to increase again.

2. The kinds of whales

5. In the 17th century: fleet forms of commercial whaling

6. In the 18th and 19th centuries: whaling competition

7. In the 20th century: factory ships with whale harvesting

12. Now people in order to obtain benefits to destroy ecological

13. The three biggest commercial countries

15. The gray whales

16. The whales in Antarctic

18. No significant amount of whales recovery has take place