How much microplastic do whales eat? Up to 10 million pieces per day, Stanford research finds
Depth of rorqual whale foraging in relation to microplastic in the water column. a Plastic ingested by whales day−1, modeled as the sum of (i) plastic filtered from water per day and (ii) plastic consumed in prey per day. We created three scenarios to capture the range of possible exposure risk of plastic ingestion, low, medium, and high, since some of the variables lack comprehensive data; b Lunge depths from deployments in Monterey Bay aligned with the depth profile of plastic concentration in Monterey Bay. Whales and prey items were illustrated by Alex Boersma and the cut-away filtration diagram was illustrated by Scott Landry at Center for Coastal Studies. Credit: Nature Communications (2022). DOI: 10.1038/s41467-022-33334-5

The largest animals ever to have lived on Earth consume the smallest amount of plastic.

The study was published in Nature Communications and focused on blue, fin, and humpback whales and their consumption of plastic fragments no bigger than a few grains of sand. The authors combined measures of microplastic concentrations up and down the water column off the coast of California with detailed logs of where hundreds of whales carried tracking devices foraged for food.

The whales mainly feed 50 to 250 meters below the surface, a depth that coincides with the highest concentrations of micro plastic in the open ocean. The blue whale is the most plastic creature on the planet, with an estimated 10 million pieces of plastic daily.

The massive size of them puts them closer to the water than you might think. According to study co-author Matthew Savoca, there is only one link between the whales and the plastic.

Humpback whales eat herring and anchovies, while those who eat mostly krill ingest at least 1 million pieces of plastic. 3 million to 10 million microplastic pieces are eaten daily by fin whales. Savoca said that consumption rates are likely to be higher for whales in polluted areas.

The authors found that almost all of the microplastics that whales consume come from their prey.

The research suggests that whales may not be getting the nutrition they need to survive.

"We need more research to understand if microplastics give fish the idea that they're full, and if they grow less oil rich, and if that's due to having eaten microplastics that gives them the idea that they're full," said Kahane- Rapport If true, this would mean that an animal the size of an 18-wheeler can't afford to lunge for food.

It's a waste of time if patches are dense with prey but not healthy. It's similar to training for a marathon and eating only Jelly beans.

Environmental change is tracked by spies.

More than a decade of data collection and analysis has answered seemingly simple but fundamental questions such as how much whales eat, how they feed, and why they grow so big.

They use a variety of technologies, including drones and sensor-laden devices known as biologging tags, which Goldbogen's team suction-cups to whales' backs to collect movement and physiological data They use sound waves to map the depth and density of fish and krill patches close to where whales are feeding.

The group's rare trove of detailed information about whales' lives and biology has been connected to plastic pollution for the first time. The authors say that the cumulative impacts of multiple stressors need further attention.

At least 1,000 species have been found to have eaten plastic, which was first reported 50 years ago. Savoca said that the concern for whales is that they can consume a lot.

Senior study author Jeremy Goldbogen said baleen whales evolved to process and filter vast amounts of the ocean, so they represent a sentinel of environmental change.

Scientists are trying to understand what happens to the plastic that whales ingest. It might be scratching the stomach lining. It can either be absorbed into the bloodstream or passed through the animal. "We don't know what we're going to do with whales' sieve-like baleen plates to develop better systems for filtering out plastic fragments and other unwanted materials in industrial settings."

Goldbogen said that the new results represent an important first step towards understanding the effects of microplastics on whales. Next steps include examining how oceanographic forces create dense patches of both microplastics and prey, and how microplastics affect the nutrition of key prey species for not only baleen whales but also an array of economically and ecologically important ocean species.

Through the use of new technologies like drones, biologging tags, and echo sounders, we can learn more about the basic biology of baleen whales.

Matthew Savoca reported on the risk of microplastic ingestion by megafauna.

Journal information: Nature Communications