Since last Thursday afternoon, when hikers in the Point Reyes National Seashore found a five-foot whale washed up on the coastline near Abbotts Lagoon, scientists have been wondering why a rarely seen species beached on Marin shores with no obvious cause.
The juvenile male pygmy sperm whale did not show signs presented by most beached members of its species: heart failure or a body full of discarded plastic. “We didn’t find anything on the outward necropsy itself that we could say definitively caused the animal’s death,” said Claire Simeone, a conservation medicine veterinarian with the Marine Mammal Center. “This is a bit of a curiosity.”
According to the center, pygmy sperm whale strandings are rare on the West Coast, where the animals tends to remain in deeper ocean waters than their East Coast counterparts. Over the past 30 years, the center has recorded only six other instances of pygmy sperm strandings. Each one has provided a wealth of information for California’s marine biologists.
“They’re a very elusive species,” Dr. Simeone said. “We don’t know very much about them at all.”
Pygmy sperms grow to around 11 feet, usually travel alone or in small groups and seldom breach the surface. Unlike other whales—but like many cephalopods—pygmy sperms carry an ink sack in their intestines that they use to shoot out pools of ink to blind and evade predators.
Thursday’s whale was still alive when it was discovered. The hikers notified the seashore, which activated a collective of organizations known as a marine-mammal stranding network.
“We sent out a couple of our biologists on staff in the afternoon to find the animal, which they did,” said John Dell’Osso, a spokesperson for the seashore. “We made sure that the tide was not going to take it out.”
But until volunteers from the stranding network could arrive, scientists had little option but to wait. And as darkness fell, the network decided to postpone the recovery effort until the following morning, by which
time the whale had died.
After the response team took blood samples, the 200-pound whale was hauled onto a wheeled gurney and lifted into the bed of a pickup truck.
The Marine Mammal Center—one of the organizations that sent staff to retrieve the whale—cited safety concerns as its primary reason for delaying the recovery. But even if the response team had arrived that first day, the whale would have been euthanized. Less than one percent of stranded whales have been successfully rehabilitated and returned to the ocean, the center said.
“When [whales] strand on the California coastline, unfortunately, the chances of them surviving is very slim,” said Laura Sherr, a spokesperson for the Marine Mammal Center. “It’s tough, but our goal is to do what is best for the animal. At that point, ultimately, the best thing to do is to painlessly put the animal to rest.”
Once the whale arrived in Sausalito, a team of five veterinarians performed a standard necropsy procedure. They cut open the body and noted that no lesions were present, that internal organs were intact and that further testing was needed to determine the cause of death. Tissue samples were then sent to several university labs across the country and the results will be returned within three to four weeks.
Aside from the veterinarian team, around 20 biologists and volunteers were also at hand to observe the necropsy. Most of what biologists know about pygmy sperm whales in California is the result of strandings, and the chance to witness a live necropsy comes once in a blue moon. “It was a great opportunity to have a learning experience for people who have never seen a pygmy sperm whale,” Dr. Simeone said. “Because we see so few, we don’t have a good idea of what these animals are like in the wild. Each one provides a large amount of information on this species.”
Dr. Simeone noted that the whale had shrunken eyes—a possible indication of dehydration that can occur when a marine mammal’s food source becomes scarce.
In the past, food scarcity has proved to result from warmer ocean temperatures that herald an El Niño event. In 2009, masses of starving sea lions whose food sources had fled to cooler waters washed up on Chilean beaches prior to the Pacific’s most recent El Niño.
Still, the National Marine Fisheries Service cautioned that it is too soon to speculate that environmental changes played a role in the whale’s death.
“Animals strand on beaches just like any other type of animal dies in the wild, from malnutrition or predation or disease,” said Chris Yates, the assistant regional manager for the agency’s West Coast Protected Resource Division. “Even with an advanced necropsy, it’s hard to know what the root cause was.”