Sentence:  <WSD>Whalers</WSD> have always overexploited their stocks, driving them to commercial extinction....American <WSD>whalers</WSD>, operating at first from the coast and later in sea-going boats, took about 200 000 right whales in addition to humpbacks and grays. 
Meaning of the word marked with <WSD> tags:  One who hunts whales; a person employed in the whaling industry.