not quite right.  Whales were extremely plentiful and became almost extinct, due to our consumption of their body oil and fat.  Because they were near extinction, they became very expensive to hunt.  Petroleum produced kerosene was sought as a cheaper alternative.  The oil industry was simply following market forces, it had nothing to do with saving a species from extinction.  Absolutely nothing.  As a matter of fact, whales are still not out of the clear.  The right whales for eg may be functionally extinct.