Whaling was an important but ultimately ephemeral business. As a consequence of extensive hunting, whale stocks were depleted and the rate of return on capital started to attenuate. In 1800, there were around 1.1 million sperm whales globally, but by 1880, due to the intensity of whaling, only about 780,000 remained. In 1853 alone, the US whaling fleet killed eight thousand whales. While the mean rate of return on whaling ventures was somewhere in the region of 15 to 24 percent per annum during the golden age in the middle of the nineteenth century, by the 1870s annual rates of return were in the low single digits. With the advent of alternative energy sources (specifically, crude oil) and higher costs of labor and foreign competition, the whaling industry declined and capital sought out new sources of return.