Something is killing the gray whales. Is this a sign that the oceans are in danger?

For thousands of years, eastern Pacific gray whales have made one of the longest annual migrations of any mammal — starting in the cold waters of the Arctic, then down past the heavily populated coastlines and beaches of California, before finding refuge in the warm, shallow coastal zones of Mexico’s Baja California Peninsula. Only to turn around a few weeks later and head back north.

As of December 2018, this magnificent migration has taken a fatal turn for them.

The bodies of California gray whales began to behed ashore along the sheltered bays of Baja, where gray whales come each spring to feed their young and mate. The first to die was a young male that washed ashore on Arena Island in Guerrero Negro Lagoon. Two days later, the decomposing body of a young female was found in the waves on a beach in Ojo de Liebre Lagoon, a few miles south of the first.

Then, on Jan. 4, 2019, three more young whales were found dead in the same lagoon, all badly decomposed.

“We’ve never seen anything like this before,” said Ranulfo Majoral, 56, son of Pacico Majoral, one of the first owners of an ecotourism whale-watching business in the region. “It’s a safe place for whales. It’s not a place where they die.”

What Mayoral witnessed was the beginning of a whale extinction that has alarmed millions of whale watchers and baffled scientists along the west coast of North America for 2.5 years. Gray whales are known for their endurance and resilience – “ocean jeeps,” as Wayne Perriman, a biologist with the U.S. National Oceanic and Atmospheric Administration, calls them – but something went wrong.

Scientists are now trying to figure out what’s killing these 40-foot-long marine mammals. What, exactly, is not entirely obvious.

Some scientists think there may be too many whales for the population to sustain itself. Others say this explanation of “excessive numbers” and “natural causes” overlooks the range of dangers that gray whales face, including ecosystem changes, ship strikes, entanglement in fishing gear, plastic pollution, disease, ocean acidification and the disappearance of kelp.

In addition, there is climate change, which is melting Arctic ice sheets, changing ocean currents, warming water temperatures, and potentially altering the food supply for whales and other animals.

Researchers, however, agree on one thing: Science must determine the key cause. Gray whales are a conservation success story: they survived commercial whaling and recovered from near extinction thanks to wildlife conservation laws. Their ups and downs are important indicators of the health of the oceans.

“Like other large predators, gray whales are the guardians of the North Pacific,” says Sue Moore, associate professor at the Center for Ecosystem Watch at the University of Washington. She notes that while their current populations are far from endangered, these whales have something to tell us that will have implications for all marine life as well as humans.”

From 2019 through July 29 of this year, 481 whales made landfall along North American beaches, including 69 in California. While it’s possible that the extinction is part of a natural cycle, if the trend continues, “well, that’s the thing that keeps me up at night,” said John Kalambokidis, senior research biologist and co-founder of the Cascadia Research Collective, a marine mammal research center based in Olympia, Wash.

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