Solitude along the Sea of Cortez shoreline was shattered recently when a 15-foot great white shark began to thrash violently in the shallows. Dale Pearson, who owns a house in the Baja California community of Puertecitos, thought at first that a pilot whale was trying to strand, or that an extremely large hammerhead shark had come in to hunt. Pearson and a friend hurried to the water for a closer look, while the commotion also captured the attention of Mexican fishermen camped on the beach. When they realized it was a full-grown great white shark, they guessed it had become trapped in a net. But they soon realized it had been struck by a boat propellor, behind its dorsal fin, and was seriously injured.