A whaling ship was a type of martime Earth ship. This ship was involved in the hunting and processing of whales. For centuries, these two activities were conducted on a single ship. By 1986, the ships became more specialized and the tasks were divided between whale catchers (the "hunters") and the processing ships. Whale catchers were equipped with harpoon guns.
In 1986, a Scandinavian whale catcher was hunting whales in the Bering Sea. After spotting George and Gracie, this ship gave pursuit to these whales. The ship's crew were denied their chance to kill a whale when the HMS Bounty intercepted the harpoon. (Star Trek IV: The Voyage Home)