Microplastics are tiny pieces of plastic debris found in lakes, rivers and oceans that come from the breakdown of larger plastics.
Researchers discovered that blue whales ingest so much of the microplastics because they exclusively eat krill, a shrimplike animal.
“The krill eat the plastic, and then the whale eats the krill,” Matthew Savoca, the study co-author said in a statement.
Blue whales were found to consume the most microplastics because they are “50 to 250 meters below the surface, a depth that coincides with the highest concentrations of microplastic in the open ocean,” the study found.
The research also focused on humpback and fin whales and found that those whales intake a slightly smaller amount of microplastics than blue whales because of the different foods in their diet.
Humpback whales, which eat primarily fish, ingest about 200,000 pieces of microplastics each day, and fin whales, which eat krill and fish, ingest about 3 million to 10 million pieces of microplastics per day.
The study also found that all the microplastics that the whales ingest come from their prey, not the enormous amounts of seawater they intake when trying to catch their food.
Even so, these findings make scientists question if whales are getting the proper nutrients they need to survive.
“We need more research to understand whether krill that consume microplastics grow less oil-rich and whether fish may be less meaty, less fatty, all due to having eaten microplastics that gives them the idea that they’re full,” Shirel Kahane-Rapport, the lead study author and a Ph.D. student at Stanford said.
Researchers for this study measured the microplastic concentration along the California coast and combined that with tracking data from 2010 to 2019, detailing where whales look for food worldwide to find the estimated amount of how much microplastics each whale intakes.
In July, Gov. Gavin Newsom signed legislation to reduce the use of single-use plastic packaging for products such as shampoo and laundry detergent in California to lower the number of microplastics in the ocean.
Under the bill, the state plans to reduce the use of single-use products by 10% and then by 25% in 2032.
Amy Wolfrum, California ocean policy senior manager at the Monterey Bay Aquarium, told the Associated Press that the bill was a “fantastic start” to addressing a significant problem.