At the height of New Bedford’s participation in the whaling industry, Yankee whalemen hunted four primary species: right whales and sperm whales in all the oceans, grey whales on the west coast of America, and bowheads in the Arctic. Little was known about the size of whale stocks or the migratory patterns of the different species of whales that was not learned directly through the process of hunting them. 

Handheld tools, sail and oar power, and the small-boat approach to the prey ensured that many whales got away; but Yankee whalemen killed every whale they could, even if it meant killing a calf to take its mother. A four-year voyage could be counted a success if it had taken and processed only fifty-some whales. Nonetheless, the large number of vessels active at mid-century, and the concentration of effort on specific species located in well-identified locations, known as whaling grounds, meant that those grounds would inevitably see a dramatic decrease in population. 

In 1851 the hydrographer Matthew Fontaine Maury published a chart of whale population derived from the logbooks of American whaling voyages. By that time the North Atlantic Ocean was already stripped of sperm and right whales. The discovery of the breeding and calving grounds of grey whales in the shallow bays of Baja California in 1846 led to a hunt that very nearly decimated the species in just a few decades. By 1900 bowhead whales were almost extinct in the Arctic. 

To make a profit in the 20th century, new technologies were required that would allow whale hunters to chase the faster, more sinkable species. Such a hunt, pioneered by the Norwegians, became popular in Antarctic waters beginning around 1920. New Bedforders were still involved in the hunt then, to a limited extent, and using the old technology, now an anachronism. The crew of New Bedford’s final whaling vessels, many from the Azores and Cape Verde, found themselves facing competition from steam-powered vessels with harpoon cannons at the bow. These “catcher boats” were as large as or larger than the New Bedford ships and schooners. They worked in company with factory ships large enough to drag a blue whale up onto the deck for processing. By 1930 right whales were facing extinction, and their hunt was banned worldwide. 

The new technology wreaked havoc on the species that New Bedforders had never successfully hunted commercially. By 1982 in the southern hemisphere, humpback whales were reduced to 2 percent of their original population; blue whales to 5 percent, and finbacks to 21 percent. In 1972 the United States Congress passed the Marine Mammal Protection Act, which banned the hunting of marine mammals and the trade in products made from them. The native people of Alaska, who had hunted bowhead whales for generations before New Englanders arrived, were granted an exception to the law, and continue to hunt whales under quotas established to protect the current population.