Also known as the grey-backed whale, the adult whale is 10 to 15 meters long, weighs 41 tons (90,000 pounds), and has a lifespan of between 55 and 70 years.
They prefer to survive in seas where water temperature and light are more suitable, especially near temperate seas. It is the species with the longest migration distance among mammals, with a migration distance of up to 10,000-22,000 km.
Gray whales are found in the North Pacific, North Atlantic, North American coast, Sea of Okhotsk, Bering Sea, Sea of Japan and china near the Yellow, East and South China Seas.
But the northwest Pacific gray whale near China is on the verge of extinction.
This is because the Japanese have been hunting whales since the 1570s. In particular, between 1911 and 1933, Japanese companies set up multiple whaling stations on the Korean Peninsula, and Japanese whalers killed 1,449 gray whales off the coast of China.
By 1934, the Northwest Pacific Gray Whale was on the verge of extinction.
Between 1891 and 1966, about 1,800-2,000 gray whales were killed, and during the peak of hunting in the 1910s, about 100 to 200 died each year.
Although gray whales have been listed on the IUCN Red List of Threatened Species a few years ago, Asian populations have been slow to recover, with the current population estimated at only 200.
Because of whaling, the American population was only a few hundred in the early 20th century, but after hunting was banned by international agreements in 1947, it was restored to 30,000 in 2004.
From late May to late October, grey whales from the American population travel an average of about 185 kilometres a day from the Arctic Circle, where water temperatures and light are more suitable, from late May to late October, from the American population to the south along the coast of the North American continent. Breeds in February on the western side of the California Peninsula, where water is warm and well-lit, and on the south side of the Gulf of California. After February, the northward advance began again, but the route was different from when it went south, with a round-trip distance of about 18,000 kilometers from the feeding grounds in the summer to the breeding grounds in the winter.
April and May are the time for gray whales to head north, but this year their journey does not seem to be going well.
San Francisco Bay, also known as San Francisco Bay, located in San Francisco, California, in the western United States, is the only way for gray whales to travel north. Since March 31, 2021, the carcasses of gray whales have been found here.
The whales originally spent the winter in Mexican waters before mating and laying off the coast of California. Departing from the California coast in the spring and summer, it begins its return to the north, feeding on anchovies, sardines and krill before continuing northward towards cool, food-rich Arctic waters.
But on March 31, 2021, the carcasses of the first adult female gray whale, 12.5 meters (41 feet) long, began appearing in Crissyfield, San Francisco. On April 3, a second adult female whale was found at Moss Beach in San Mateo County. On April 7, a third gray whale floated near Berkeley Pier, and the next day, another gray whale was washed away at Muir Beach in Marin County.
And this isn't the first year gray whale carcasses have been found in the Bay Area.
At least 13 dead whales were washed off the coast in 2019. At that time, the National Oceanic and Atmospheric Administration had declared that gray whales had "unusual deaths".
Biologists believe the whales are starving because of a food crisis and are unable to complete their annual migration from Mexico to Alaska. Because since 2019, the body of gray whales during the annual migration has been observed by biologists to have malnutrition.
However, this gray whale death is slightly different. Experts said photos provided by the U.S. Marine Mammal Center showed one of the adult female gray whales washed up on Muir Beach, the cause of death believed to be the result of trauma caused by the impact of the vessel.
In recent years, researchers have found that starvation, wounds from entanglement in fishing gear and boat impacts are the most common forms of death for gray whales.
Through the dissection of whale carcasses found at Muir Beach, there were significant bruises and bleeding in the muscles around the whale's jaw and neck crest, which was consistent with blunt force trauma caused by the impact of the vessel. At the same time, judging by the layer of blubber and the level of internal fat, the whale is in good physical condition and eats well.
But while it's shocking to see so many whale deaths in a matter of days, what we're seeing is only the tip of the iceberg of the death army.
As human activity increases in Mexican waters, in addition to fishing gear entanglement, boat collisions, climate change, acute noise, and toxic spills, as well as fossil fuel exploration and extraction, have all affected the survival of gray whales.
Even solar activity increases the probability of gray whale stranding, with data showing that gray whales are five times more likely to run stranded when sunspots are prevalent.
The most reliable explanation for this phenomenon is that solar storms release large amounts of electromagnetic radiation, which interferes with the Earth's magnetic field and the analysis capabilities of whales.
According to the National Oceanic and Atmospheric Administration, nearly a quarter of gray whales migrating along the west coast of the United States have died since 2015 and 2016 were recorded.
Feel free to sum it up
Overall, grey whales in the American population have been effectively restored under years of protection. The lack of food shows that the number of gray whales there has reached the limit that the environment can accommodate, but the phenomenon of unnatural deaths of gray whales is also more frequent and requires continuous attention.
There is still a long way to go for the recovery of the Asian population of gray whales, but the most important thing is that Japan is merciful.