The problem with such stories is that they leave a lot of questions unanswered. Why were people so cruel and evil? Why did they hunt whales eventhough there were so many other sources of vegetable and mineral oil? What was so special about the mid-1970s? Initially, the sperm whales were hunted mainly to produce stearin and lamp oil. In the 1870s, cheap paraffin oil became available, and the demand for sperm oil decreased dramatically. Around 1900, it started to increase very rapidly; never was it so high as in the early 1970s. How did it happen?
...Sperm oil is the oil from the head cavity of the sperm whale. Stearin and spermaceti may be separated from sperm oil at low temperature. Spermaceti is extracted from sperm oil by crystallisation at 6 °C, when treated by pressure and a chemical solution of caustic alkali. (Wiki)
The oil-filled cavity is used mainly for echolocation, but when the sperm whales dive, they pump cool blood into these cavities: the wax esters solidify at lower temperature and higher pressure and becomes dense, so it is another example of lipid-controlled buoyancy. http://www.nature.com/nature/journal/v228/n5274/abs/228873a0.html
The main component of spermaceti, cetyl palmitate, is a unique lubricant. It binds strongly to iron oxide on steel through its ester group. When the temperature and pressure increases, aliphatic arms go through a series of conformations, changing the friction coefficient between the steel and hydrocarbons contacting the lube. When sperm oil was replaced by petrochemicals in the 1870s, cheap hydrocarbon fuels became available. Very soon the engine using petrol was invented, but this is not enough to make a car: there are mechanical parts in the engine and gear box needing lubrication. Mineral oil based lubricants proved inadequate for such applications, but the sperm oil was perfect for lubricating heavily loaded gears. The demand started to grow and increased sharply in the 1940s when the automatic transmission was developed. Automatic shifting of the gears requires that the friction coefficient responds to sheer in a certain way, and only sulfurchlorinated sperm oil had the correct type of response curve in the required range of heat and mechanical loads.
As most cars built in America by the 1960s had automatic transmission, the demand for sperm oil became greater and greater. There is only one plant (jojoba) making similar wax ester, but it proved impossible to cultivate this plant on the required scale (they tried that in the 1950s). So there was huge automotive industry lobbying to keep the whale harvesting going, representing many millions of people. Chemical industry has been trying to make synthetic wax esters for many years, but nothing worked well for the automatic transmission fluid (ATF). In the 1970s, the car companies were required to develop engines working at higher temperatures to comply with lower emissions and improved efficiency and that changed the regime for the tranny fluids. Suddenly, the car companies did not need to lobby any more. The government stockpiled sperm oil for its own needs, and then the US banned whaling to no opposition. Tellingly, the car companies miscalculated: they did not have the replacement, resulting in massive transmission failures.
...By WWII development of automatic transmissions was well underway, utilizing the qualities of sperm oil. The torque converter's introduction right after the war gave the automatic transmission the technology required for acceptance by the driving public and by the 1950s automatics were the preferred transmission. By the 1960s up to 30 million pounds of whale oil were used each year, chiefly as the main additive to automatic transmission and locking differential fluids. It was whale oil that made these devices so reliable and efficient and it was primarily the auto industry's requirements that maintained the demand for whaling during the mid-20th Century. Automatic transmissions ran smoothly and reliably using whale oil in lubricating fluids, as long as engine coolant temperatures ran below 173 F.
...Fortunately for the whales, by the 1970s engines became subject to tighter emissions regulations and engineers had to design them to run hotter. Other demands such as front-wheel-drive and ever-increased emissions limits boosted the operating temperatures of engines to well over 200 F, forcing research efforts into synthetic lubricants. http://www.secondchancegarage.com/public/725.cfm
...For complex systems such as transmissions, synthetic and animal substitutes proved to be inadequate, leading to poor overall drive train performance, premature drive train failure and failure due to heat. Automatic transmission failures went from less than a million units in 1972 to over eight million units a year by 1975, due to the loss of sperm whale oil additives. Today, there are over 11 million automatic transmission failures per year (90%) are caused by the degradation of automatic transmission fluid due to heat. Heat promotes the oxidation of transmission fluid, and that compromises its performance and accelerates wear on the internal components of automatic transmissions. http://lubegard.com/news/?p=127
Needless to say that such failures translate into car accidents and loss of human life. It was true that increased heat load destroyed the modified sperm oil in the ATF faster. The problem was that its freshly developed synthetic analogs were performing even worse. Only in the 1980s, a chemical solution to this problem was found, and I highly doubt that it could have been found earlier. Now we have the pieces of the story:
Sperm whales use unusual rheological properties of wax esters in order to control buoyancy, and these properties also make such chemicals an ideal lubricant for extreme pressure applications. When the world relied on whales as a source of hydrocarbons, these were too expensive to use as fuels, and the demand was self-limiting. When the whales were “saved” by petrochemical industry, it was only a short respite. Petrol-powered machinery required new types of lubricants that increased rather than decreased the reliance on sperm oil. Petroleum was plentiful, the cars filled the world, and it is at that point that the whales began to disappear. Literally nothing was done to save these whales until the cars evolved to the point when the engines started to operate at a higher temperature; the latter was caused by the concern about human health and efficiency rather than the well being of these whales. The environmental activists drove their cars just like everyone else, and they consumed transported goods and benefitted from sperm oil based lubricants in a myriad other ways, sustaining the demand. It was not their attention grabbing activities that stopped killing whales, but the unsung efforts of chemists finding a synthetic replacement to sperm oil. Meanwhile, human lives were lost through multiple transmission failures.
The reason why so many whales were killed in the 20th century was the distant ramifications of replacement of whale oil by petroleum. It took another 100 years to find solutions to these ramifications, and only then it became possible to save the whales. Ecological activism did not play significant role in all of these developments; neither did the numerous well-meaning international treaties, moratoriums, and other chest beating displays.
A chemist who saved the whales has not merited a Wikipedia entry. His name was P. S. Landis and he was a researcher at Mobil Oil.