India, Oct. 8 -- Some conservation stories begin with a rescue; this one begins with a factory plan. Each winter, gray whales come to the calm waters of Laguna San Ignacio, a lagoon on Mexico's Pacific coast, to give birth. According to UNESCO, the whale sanctuary that includes this lagoon holds the most important breeding grounds of the eastern North Pacific gray whale. But in 1995, a proposal for a massive saltworks put that quiet spot at risk. Among those who pushed back were actor Pierce Brosnan and his future wife, Keely Shaye Smith.

Laguna San Ignacio is in Baja California Sur. It is part of the UNESCO World Heritage site Whale Sanctuary of El Vizcaino, inscribed in 1993, just before the saltworks plan came up. Gray whales migrate ...