Four gray whales were found dead in California Bay within eight days

The carcasses of four gray whales were found in eight days around the San Francisco Bay Area – a disturbing series of deaths that is an unusual death event, defined by the National Oceanic and Atmospheric Administration (NOAA) as a significant death of a marine species.

Marine researchers do not know the reason for the spate of whale deaths, the latest of which took place Thursday. But they are committed to finding answers, even if the pandemic has an impact on the efficiency with which they can conduct their research, Dr. Jeff Boehm, a veterinarian and CEO of the Non-Profit Marine Mammal Center, the world’s largest veterinarian for veterinarians, said.

Although they are not endangered, the population of the gray whale is declining rapidly: 1 in 4 gray whales has died according to the last population assessment in 2016, according to NOAA. The agency, along with the Marine Mammal Center and the California Academy of Sciences, is working to find the cause of the decline before the gray whales are no longer a biennial visitor to California.

Whales die from shipwrecks, malnutrition and entanglement

The whale, a 41-foot-tall female, was found in nearby Muir Beach on Thursday. He died in a shipwreck, Boehm said. He added that he had experienced bruises and bleeding. Another whale that died last week is thought to have died in a boat strike, but the causes of death of the other two whales are unknown.

Necropsy performed in recent years has identified the gray whale’s three most common causes of death: malnutrition, ship attacks and entanglement, Boehm said.

Malnutrition is likely to be linked to climate change, Boehm said. The whales travel north in the spring towards the North Pole, where the waters are usually rich with the invertebrates feeding the whales with the bottom. But as water temperatures rise, the food they feed may no longer make their home in the Arctic waters, and the whales will be hungry for the next few months if they do not feed regularly as they migrate.

Anecdotally, Boehm said he recently saw a “revival” in shipping after the pandemic slowed international trade. More information is needed to determine how or if the ships engage in the unusual death, he said.

A similar death occurred in 2019

A similar death occurred in 2019 when Boehm said three gray whales were found dead within one week. Nearly halfway through that year, 69 whales were found dead in the U.S. and 147 whales died in general.

It is unknown whether a similar death will occur in 2021, and whether the most recent series of deaths is related to the unusual death in 2019, Boehm said. The pandemic halted the typical robust research projects of the Marine Mammal Center, Boehm said, as teams must comply with Covid-19 safety measures while working. But the recent events are disturbingly similar to the events in 2019, he said.

“Four in eight days is just a little more extreme for me,” he said.

Teams continue to study gray whales in the field and note how the whales live with the vessels that share the waters of the Bay. They monitor things like ship traffic and the speed at which the ships travel, but also the condition for which the whales are, if ships alone are not the answer to the recent demise.

San Francisco likes the whales that travel twice a year, Boehm said.

“What a remarkable thing to have, an urban center like the San Francisco Bay Area, with all its economic power and this significant population center, right next to the waters teeming with wildlife,” he said.

Boehm said the rest of the marine ecosystems in the Bay Area are suffering from the gray whale population. It is therefore crucial that marine biologists find answers to the most recent unusual death event and, more importantly, create long-term solutions.