In less than three weeks since a dead whale washed ashore in San Francisco, a beached 32-foot female humpback whale was discovered, baffling biologists. The latest theory states that a collision with a ship may have killed the whale.

The humpback whale's carcass was discovered in the waves, so personnel from the California Academy of Sciences and the Marine Mammal Center were unable to perform a necropsy safely. Initially, it was floating in the surf a few days prior. The whale was located within sight of another carcass, of a sperm whale, that beached in April. The humpback whale is the third to be found dead in San Francisco this year. In January, a rare pygmy sperm whale was also beached.

Biologists are still unsure what caused the death of the first whale, which was found at Mori Point at the southern end of Pacifica's Shark Park State Beach. The 50-foot sperm whale did not have broken bones but had bleeding in its muscles, though there was not enough damage clearly pointing to blunt force trauma. The whale had not been receiving enough sustenance but it did not die from hunger since it had been eating, as shown by an examination which revealed squid beaks in its stomach.

The two cases could be coincidental, most likely a result of strong onshore winds that could have forced the animals in the area onto the beach.

"There tend to be peaks in whale strandings in the spring and fall, aligned with the migration and calving season," explained Lauren Rust, a research biologist from the Marine Mammal Center in Sausalito.

Rust added that they are hopeful conditions at the beach would improve because this will allow them to fully examine the animal. Every stranding is an opportunity for the Marine Mammal Center to learn more about whales and the ocean environment.

Laura Sherr from the Marine Mammal Center speculates that the humpback whale may have collided with a ship after spotting signs of hemorrhaging. However, biologists only found one broken rib, which makes the ship collision theory less likely. Additional injuries include four broken vertebrae.

Listed as endangered, humpback whales are protected by the Endangered Species Act. It is normal to see them in California as the state's waters are part of their regular migratory route. Offshore, it's possible to observe them aboard boats.

Living to up to about 50 years, humpback whales are characterized by long pectoral fins that can grow up to 15 feet. Whale watchers like this whale because of its aerial displays, like jumping out of the water or breaching and slapping the water's surface with its head, tail or pectoral fin. Humpback whales can be found in all of the major oceans in the world.

Photo: Gregory Smith | Flickr

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