Dozens of female gray whales that are pregnant, many of which are ready to give birth, began to arrive this month in the Sea of Cortez, off the Mexican state of Baja California, in keeping with a natural cycle that could come to an end if tourism development plans continue, say environmentalists. ''The concern is that the government (of President Vicente Fox) will follow through with its plans that threaten the whales and other species in Baja California in silence, in secret,'' Homero Aridjis, president of the environmental Group of 100, told Tierramérica.

The whales arrive from the Arctic, gathering in an area where there is intensive real estate development. The government also plans to establish the zone as a stop for cruise ships from all over the world, including the construction of 20 ports to attract more such tourists.

According to Aridjis, although the project seems to be on the decline due to the strong opposition by environmentalists, '' the danger of destruction remains latent.'' The Sea of Cortez is considered a sanctuary for gray whales, sea lions, sea turtles, and other marine animals