Endangered Gray Whales: Threats, Humans, Orcas, Mass Die-Offs

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When the western and eastern Pacific populations of gray whales are considered a single population, the International Union for Conservation of Nature (IUCN) considers them as a species of "Least Concern". However, the western Pacific population is separately listed as “critically Endangered”.The Convention on International Trade in Endangered Species (CITES) lists gray whales in Appendix I, which lists that are the most endangered among CITES-listed animals and plants. The Committee on the Status of Endangered Wildlife in Canada designated the eastern north Pacific gray whale as a species of "Special Concern". The Marine Mammal Protection Act (MMPA) lists them as depleted.

After international protection from commercial whaling, gray whale populations experienced a 2.5 percent annual growth increase until 1998, when the population peaked at around 27,000 individuals. Over the following four years, however, the population declined by more than a third, possibly due to a lack of food in their summer feeding grounds. Since 2002, the eastern north Pacific gray whale population has steadily increased. [Source: Travis Kidd, Animal Diversity Web (ADW) /=]

The eastern population was once listed as endangered under the U.S. Endangered Species Act but successfully recovered and was delisted in 1994. The western population remains very low, around 200 individuals, and is listed as endangered under the Endangered Species Act (ESA, U.S. Fish and Wildlife) and depleted under the Marine Mammal Protection Act. [Source: NOAA]

In 2003, the International Whaling Commission (IWC) established an indigenous hunting limit of 620 gray whales over five years, with no more than 140 individuals to be taken in a single year. In 2005, the IWC estimated that 400 individuals could be sustainably taken in any one year. Additionally, the major breeding lagoons of the eastern Pacific population are protected by their inclusion in the El Vizcaino Biosphere Reserve, limiting disturbances from boating, fishing, and coastal development.

Websites and Resources: Animal Diversity Web (ADW) animaldiversity.org; National Oceanic and Atmospheric Administration (NOAA) noaa.gov; Fishbase fishbase.se; Encyclopedia of Life eol.org; Smithsonian Oceans Portal ocean.si.edu/ocean-life-ecosystems ; Monterey Bay Aquarium montereybayaquarium.org ; MarineBio marinebio.org/oceans/creatures

Gray Whales and Humans

Most gray whales avoid human contact. Certain whales are deemed "friendly." They often seek out humans rather than visa versa. Some gray whales let divers approach them and stroke them. Others approach boats with whale watchers. Some rambunctious whales have flipped whale watcher out of their boats.

Describing the friendly behavior of a curious gray whale named Amazing Grace, Steven L. Swartz and Mary Lou Jones wrote in National Geographic, "She readily adopted us along with our 14-foot inflatable outboards as her personal toys. She would roll under the boat, turn belly up with her flippers sticking three to four feet out of the water on either side of the craft, and lift us clear off the surface of the lagoon, perched high and dry on her chest between her massive flippers."

"When she tired of bench press technique, Grace would do the same thing with her head, lifting us out of the water and letting us slide off to swirl around her in circles...At other times Grace would submerge beneath us and release a tremendous blast of air that boiled to the surface in a giant Jacuzzi of white water...After such gymnastics Grace would lie quietly alongside the boat to be rubbed. We would oblige her with a vigorous massage along her back, head, and ribs, while she opened her mouth to display huge fringed curtains of creamy white baleen plates."

Threats to Gray Whales

Threats to gray whales include entanglement in fishing gear, vessel strikes, ocean noise, disturbance from whale watching activities and climate change. Gray whales have migrated to areas that have been overfished and fishermen have been encouraged to go into the whale-watching business to help fish stocks rebound and provide the fisherman with income. [Source: NOAA]

Entanglement in Fishing Gear: Gray whales are at high risk of becoming entangled in fishing gear, either swimming off with the gear attached or becoming anchored. Once entangled, whales may drag and swim with attached gear for long distances. This can result in fatigue, compromised feeding ability, or severe injury, which may ultimately lead to death.

Vessel Strikes: Collisions with all sizes and types of vessels are one of the primary threats to marine mammals, particularly large whales. Gray whales are one of the most vulnerable species to vessel strikes because they feed and migrate along the U.S. west coast, which has some of the world’s heaviest vessel traffic associated with some of the largest ports in the country. Gray whales may also be vulnerable to vessel strikes in the inland waters of Washington and in feeding areas along the Pacific coast. There were at least two fatal accidents in spring of 2007 near San Francisco's Golden Gate Bridge. Gray whales surfacing to breathe there were been ripped apart by propellers on cargo vessels.

Disturbance from Whale Watching Activities: Whale watching has become an important recreational industry in several communities along the North American coast from British Columbia, Canada, to the gray whale wintering lagoons of Baja California, Mexico. Whale watching along this route may affect gray whale migration.

Ocean Noise: Underwater noise threatens whale populations, interrupting their normal behavior and driving them away from areas important to their survival. Increasing evidence suggests that exposure to intense underwater sound in some settings may cause some whales to strand and ultimately die.

Gray Whales and Orca Attacks

Orcas (killer whales) are the main predators of gray whales. Nearly 18 percent of all gray whales show evidence of orca attack, with juveniles being the most vulnerable. Orca’s hunt in pods and can separate a calf from its mother. Once separated from its mother, the orca pod drowns the calf by holding on to its flippers and tail flukes with their teeth. Adult gray whales often place themselves between their calf and potential predators. When under attack, adults may also swim toward shallow water or kelp beds, where orcas typically do not enter. [Source: Travis Kidd, Animal Diversity Web (ADW) /=]

Drone footage taken in March 2023 showed 30 orcas attacking gray whales in the Monterey Bay along the California coastline. Evan Brodsky told KSBW he captured the five-hour battle with a drone from a Monterey Bay Whale Watch boat. The Sacramento Bee reported: More than two dozen Bigg’s killer whales ganged up on the gray whales, which are migrating north, Monterey Bay Whale Watch said on Facebook. Bigg’s orcas, also known as transient killer whales, roam the Pacific Northwest and prefer a diet of marine mammals as opposed to other oras, which eat mainly fish, according to OrcaLab. Monterey Bay is about 120 miles south of San Francisco. [Source: Don Sweeney, Sacramento Bee, April 3, 2023]

The video, posted to Facebook, shows orcas swarming around the whales amid splashes and spouts. “Usually killer whales will hunt gray whale calves as they head up to their northern feeding areas with their moms,” the post read. “But these were not calves: they were huge adult gray whales!” The killer whales eventually broke off the attack when the gray whales split up and headed for shallower water, Monterey Bay Whale Watch said.

Mass Gray Whale Die Off 1999-2000

Malnourishment and disease claimed one quarter of the gray whale population in the late 1990s when the number of gray whales fell from 21,000 in 1997 to about 16,000 in 2000. Some scientists believe this happened because the gray whale population had simply grown too large for its primary food source and eaten more than nature could provide. Others blamed climate change.[Source: Kenneth R. Weiss, Los Angeles Times, July 2007]

Frances Gulland, who helped lead the NOAA team investigating the die-off didn't believe that climate change alone could explain the drop. She told National Geographic: “It’s common sense that there must be problems with their feeding, and we also know that there are massive changes in the Arctic. But how those changes are connected is difficult to say.” [Source: Kate Linthicum, National Geographic, April 14, 2021]

According to National Geographic: Many believe it may be a combination of factors. “I think we’re seeing an interaction of events,” says John Calambokidis, a biologist with the Cascadia Research Collective and with NOAA’s Unusual Mortality Event working group. An expanding population of whales would mean more competition for food. Paired with some other factor that may have triggered a decline in available prey — such as dramatic changes in the Arctic environment — starvation and death could follow. In recent years, more gray whales have been veering a hundred miles off their migratory path and into Washington’s Puget Sound, where Calambokidis works, in search of food. It’s a sign that the whales are hungry, the researcher says, but it's also a sign of their resilience. Whales can pack on serious weight in just a few weeks — not by eating amphipods on the ocean floor but by feasting in ghost shrimp beds in shallow parts of the sound.

In 2007, scientists from Mexico to the Pacific Northwest again reported an unusually high number of scrawny whales. That year instead of making steady progress during their migrations, whales stopped more often to eat along the way. According to the Los Angeles Times: They have been seen straining mysid shrimp from kelp beds off California and British Columbia, sucking up mouthfuls of sand in Santa Barbara Harbor and skimming surface waters for krill-like crustaceans all along the West Coast. Such opportunistic feeding has its risks. Switching to new food can expose the whales to harmful parasites and other hazards. To find food, some gray whales have been extending their 5,000-mile northerly migration beyond the Bering Strait into seas north of Alaska. It used to be a rare occurrence to see gray whales off Barrow, Alaska, said Craig George, a North Slope Borough wildlife biologist since the 1970s. In recent years they have become summertime regulars, churning up mud plumes along the shoreline in search of food.

The gray whale population rebounded after the mass-casualty event. And it didn’t just recover, it boomed, reaching 27,000 individuals in 2016.

Mass Gray Whale Die Off 2016-2020

Eastern Pacific gray whale populations plummeted again by nearly a quarter between 2016 and 2020, from almost 27,000 individuals to around 20,500 Reporting from their calving grounds in Mexico, Kate Linthicum wrote in National Geographic, The whales are arriving in the estuary later in the year, and many appear malnourished, the jagged outline of vertebrae visible on their typically fatty backs. More whales than usual have been washing up dead along the shore. Perhaps most concerning is the dramatic drop in births. On a normal early February morning like this one,” you would “expect to see several pairs of mothers and calves.” Only that day only adults were visible.[Source: Kate Linthicum, National Geographic, April 14, 2021]

All along their migration route, whales were stranding in record numbers. In 2019, 214 gray whales were found dead, including 122 in the United States — four times the nation’s annual average over the previous 18 years. Scientists believe that for each whale found on land, another five die at sea. NOAA declared an “unusual mortality event” and launched an investigation into the causes.

The origins of the decline are so far a mystery. Much of the early research points to climate change, which is rapidly warming the Arctic Ocean and may be reducing the quantity or quality of whales’ food supply. But scientists can’t rule out other factors, including the possibility that the whale population grew too large and is simply correcting itself.

Although scientists don't know for certain what caused a die-off of eastern Pacific gray whales, they believe climate change might have reduced the amount or quality of prey. Malnutrition could prevent the whales from completing their annual migration and could threaten their general survival. Warming oceans reduced sea ice cover. Algae grow on sea ice and fall to the ocean floor. Less sea ice means less growth of algae beneath it. Gray whales feed primarily on amphipods, small bottom-dwelling animals that depend on algae. A reduction in algae could in turn limit food for whales.

Necropsies — post-mortem exams on animals — are particularly difficult to conduct on whales because they often wash up on remote beaches, and they decompose rapidly. In a typical year, researchers at the Marine Mammal Center, in Sausalito, might necropsy between one and three gray whales, which don’t typically enter San Francisco Bay while migrating. But in 2019, the center examined 13. Pádraig Duignan, the center’s chief pathologist, speculates that whales veered off their usual route and entered the bay because they were hungry and looking for food. Necropsies revealed around half the whales were malnourished, with very low stores of fat around their hearts and other organs. Their entry into the bay made them particularly susceptible to boat traffic: Most of the other whales examined had succumbed to ship and ferry strikes.

Sakhalin Island Oil and Gray Whales

There is a lot of oil offshore of Sakhalin Island in far eastern Russia. The reserves have been estimated at 15 billion barrels, compared to 22 billion barrels in all the United States. There are also large amounts of natural gas there too (200 trillion cubic feet, 6 million cubic meters). Some American and European companies were attracted to the Sakhalin because the environmental laws are more lax. Companies can dump toxic drilling mud, use tankers in ice-clogged waterways, drill in fish-filled water, and don’t need t have spill-responses teams nearby as they would in the U.S. or Europe.

One of the biggest environmental concerns at Sakhalin is the gray whales that live there. The gray whales off of Sakhalin are one of just two populations in the world. They were thought to be extinct but a 1995 study found 106 of them feeding in shallow lagoon off the northeast coat of Sakhalin.

The Asian-Russian gray whales spend their summers of the coast of the Russian Far East and their winters in the South China Sea. About 100 or so gray whales feed during the summer off of Sakhalin island, near where large foreign energy companies are drilling for oil and gas. There are worries that the whales could be harmed by collisions with boats or contamination of their feeding areas by an oil spill. The use of explosives in seismic testing appears to disturb them and drive them from the area. There are plans to put pipeline and offshore platforms right in the middle of their feeding areas. The oil companies are planning to limit construction while the whales are feeding and other measures.

One of ExxonMobile’s drilling sites is next to the feeding areas for the gray whales. The company has been accused of using seismic blasting only 2½ miles form the site. ExxonMobile killed 15,000 sticklebank and smelt with a faulty culvert in a stream near a drilling site. Near one platform, 900 tons of dead herring spread out over eight miles. Officials said the die off was caused by lack of oxygen due to unusually high amounts of petroleum and heavy metals in the fish.

Image Source: Wikimedia Commons, NOAA, migration map: San Luis Obispo County Office of Education

Text Sources: Animal Diversity Web (ADW) animaldiversity.org; National Oceanic and Atmospheric Administration (NOAA) noaa.gov; Wikipedia, National Geographic, Live Science, BBC, Smithsonian, New York Times, Washington Post, Los Angeles Times, The New Yorker, Reuters, Associated Press, Lonely Planet Guides and various books and other publications.

Last Updated May 2023

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