Scientists from Stanford University have found that the largest animals that ever lived on Earth swallow the smallest plastic patches in huge quantities.

Humpback whales feed on their rush in Monterey Bay. New research shows that whales are ingesting plastic in greater amounts than previously thought, and almost all of it comes from their prey, not the massive amounts of seawater that whales ingest when they feed. (Image source: Chase Dekker Wild-Life Images/Getty Images)

Posted in nature connections, The study focuses on blue, fin and humpback whales and their consumption of plastic fragments no larger than a few grains of sand, commonly called microplastics. The authors combined measurements of microplastic concentrations above and below the water column off the coast of California with detailed records of where hundreds of whales carrying food trackers searched between 2010 and 2019.

They found that whales mostly feed 50 to 250 meters below the surface, a depth that coincides with the highest concentrations of microplastics in the open ocean. The largest creature on the planet – the blue whale – swallows the most plastic, with an estimated 10 million pieces per day because it feeds almost exclusively on shrimp-like animals called krill.

“It is lower in the food chain than you might expect due to its sheer size, which puts it closer to where plastic is in the water. There is a link,” said study co-author Matthew Savoca, a postdoctoral researcher at Hopkins Naval Station, Stanford Marine Laboratory on the Monterey Peninsula. Only one: krill eat plastic, then whale eat krill.”

Humpback whales primarily live on fish such as herring and anchovies, ingesting an estimated 200,000 microplastics per day, while those who eat mostly krill eat at least a million. Fin whales, which feed on both krill and fish, feed on an estimated 3 million to 10 million microplastics per day. Savoca said consumption rates are likely to be higher for whales foraging in more polluted areas, such as the Mediterranean.

The authors found that all of the microplastics the whales consume come from their prey, not the massive amounts of seawater these whales ingest as they rush to capture swarms of krill and smaller fish.

The study’s lead author said this is a troubling finding because it indicates that whales may not be getting the nutrition they need to thrive. Cheryl Kahane – Ruthwho worked on the research as a doctoral student in the Goldbogen Laboratory at Stanford.

“We need more research to understand whether krill consuming microplastics grows less oil, and whether fish has less meat, less fat, all because of eating the microplastics that give it the idea that it’s full,” Kahana Rothert said. . If true, this means that each expensive dash by a whale may reap fewer calories—one that an animal the size of an 18-wheeler cannot afford. “If the spots are dense with prey but not nutritious, that’s a waste of their time, because they ate something that is basically trash. It’s like training for a marathon and eating pills,” said Kahana Rothert, now an NSF postdoctoral researcher at California State University, Fullerton. Jelly only.

Guardians of Environmental Change

The research builds on more than a decade of data collection and analysis, during which Goldbogen and his collaborators have answered seemingly simple but basic questions such as how much whales eat, how they feed, why they grow so big (but not bigger), and how slowly their hearts beat. They use a range of technologies, including drones and sensor-loaded devices known as biomarkers, which the Goldbogen team uses as suction cups on the backs of whales to collect movement and physiological data. From small research boats, they also deploy echolocation devices, which use sound waves to map the depth and density of fish and krill patches near where the whales are feeding.

Students and postdocs on the Stanford University research vessel R/V Dauphine An echo sounder lowered into the ocean off the coast of Big Sur to measure the abundance and distribution of whale prey. (Photo credit: James Valbusch)

This is the first time that the rare set of detailed information about whale life and biology has been linked to plastic pollution, a rapidly spreading problem adding to threats from noise and chemical and biological pollution. “For species struggling to recover from historic whaling combined with other human pressures, our findings suggest that the cumulative effects of multiple stresses require further attention,” the authors wrote.

Whales are hardly alone in their consumption of plastic, which was first reported in marine food webs 50 years ago and has now been found in at least 1,000 species. “The unique concern of whales is that they can consume so much,” Savoca said.

“Large filter feeders such as baleen whales have evolved to process and purify huge amounts of ocean, so they are sentinels to environmental change including pollution such as microplastics,” said study senior author Jeremy Goldbogen, associate professor of oceans at the Stanford Doyr School of Sustainability. .

Scientists continue to investigate what happens with the plastic particles that whales ingest. “It could be a scratch in the linings of their stomachs. It could be absorbed into the bloodstream, or it could pass through the animal,” said Kahana Rothert, whose research at CSU Fullerton focuses on inspiration from whale sieve-like baleen plates to develop better systems for filtering plastic parts. and other undesirable substances in industrial environments, such as sewage treatment plants.

Goldbogen said the new findings represent an important first step toward understanding the potential chemical and physiological effects of microplastics on whales and other large filter-feeding animals. Next steps include studying how oceanographic forces create dense patches of both microplastics and prey, and how microplastics affect the nutritional value of key prey species not only for baleen whales but also for a range of economically and ecologically important ocean species.

“Understanding more about the basic biology of baleen whales and whale ecosystems through the use of new technologies such as drones, bio-embedding tags and echometers, enables us to conduct important translation research in sustainability and beyond,” Goldbogen said.

Goldbogen is also associate professor, courtesy of, of biology. Co-authors Max Czapanskiy and James Fahlbusch are PhD students in biology affiliated with the Hopkins Naval Station. Fahlbusch is also affiliated with the Cascadia Research Collective in Olympia, Washington. Additional co-authors belong to the University of California, Santa Cruz, and the NOAA Southwest Fisheries Science Center.

This research received funding from the National Science Foundation, the Office of Naval Research Young Investigators Program, the National Defense University Research Instruments Program, MAC3 Impact Philanthropies, the National Geographic Society, the American Cetacean Society (Monterey Bay Chapter), and Dr. Earl H. Myers and Ethel M. Myers Fund for Oceanography and Marine Biology.

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