A man tries to save 27 beached pilot whales in the Gulf of Mexico. The Mexican Secretariat of the Navy

More than 20 whales died Sunday after they became beached off the shores of a fishing village on Mexico’s Gulf of California coast.

Mexico’s environmental-protection agency, PROFEPA, along with the Mexican Navy and local fisherman, worked Saturday night into Sunday morning to save the 27 pilot whales that had become beached near San Felipe, Mexico. Pilot whales are members of the dolphin family and travel in large groups that can reach several hundred.

The low tide early Sunday morning made it difficult for rescuers to push the pilot whales out to deeper water, and even when rescuers could, some of the wales turned back around and swam toward the whales that remained in the shallow water.

PROFEPA said in a statement (translated from Spanish):

It is noteworthy that pilot whales have a strong social cohesion, that’s to say they don’t abandon other whales that are in danger, even if it means death. For example, if a whale is beached, the others will follow to be with it and the whole pod can become beached. They do not abandon others.

It is unclear why the whales ended up on shore. But a whale may beach itself for many reasons, and its pod can follow. Whales can wash ashore when they have been struck by a boat and become disoriented. Predators, like sharks, can also drive them into shallow water. And some theories posit that loud sonar like the kind used by military vessels can drive the animals out of deep waters and toward the beach.

In January, a pod of 80 pilot whales washed up along India’s southern shores. This year, an unusual amount of sperm whales have beached themselves in Europe, and are thought to be from the same pod.

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