The concentration of microplastics is particularly high at a water depth of 50 to 250 meters. This is where blue whales usually go foraging for food. US researchers estimate that the marine mammals ingest up to ten million pieces of microplastic every day.
Blue whales, the largest animals on earth, ingest around ten million pieces of microplastic every day with their food. A US research team came to this estimate after examining microplastic data and the feeding behavior of blue, humpback and other baleen whales off the coast of California. These whales filter their food from the water. The study by researchers from Stanford University and other universities was published in the journal “Nature Communications”.
Plastic particles that are smaller than five millimeters are called microplastics. The concentration of the tiny plastic particles, which can come from car tyres, synthetic clothing or packaging material, is particularly high in a water depth of 50 to 250 meters – it was at this depth of all places that the baleen whales mainly went looking for food. According to the research team, the ocean liners ingested almost all plastic particles indirectly through their contaminated prey, such as krill or small fish.
The study, based on estimates and mathematical models, relied on observations of 191 tagged baleen whales from 2010 to 2019 in areas along the California coast, including Monterey Bay and Channel Islands. Blue whales, which can be over 30 meters long and weigh almost 200 tons, could ingest an estimated 10 million microplastic parts a day, the smaller, around 15 meter long humpback whales up to 4 million particles.
Due to the large amount of contaminated food, the research team points out possible risks and stress factors for the giant marine mammals. Further investigations, for example into the health risks of consuming the plastic particles, are necessary.