Photograph: by Wildestanimal / Getty Images
According to a study, filter-feeding whales consume millions of microplastic pollution particles per day, making them the largest consumers of plastic waste on the planet.
The central estimate for blue whales was 10 million pieces per day, meaning that more than 1 billion pieces could be ingested in a three to four month feeding season. The weight of the plastic consumed during the season was estimated to be between 230 kg and 4 tons.
In highly polluted areas, or if plastic pollution continues to increase in the future, whales could eat 150 million pieces per day, the researchers warn. The data was collected in California’s coastal waters, but scientists said other parts of the world are more polluted.
The research is the first to estimate the consumption of microplastics for blue whales, whales and humpback whales, which are whales and use filters to capture their prey. He found that virtually all of the microplastic consumed is found in the krill and fish that whales eat, rather than in the water. The plastic particles are similar in size to the food that smaller organisms eat.
Whales could be harmed by the microplastics and toxic chemicals they carry, and previous work has found that plastic-derived contaminants have been identified in their fat. Mammals are still recovering from the whaling trade and face other human-caused impacts such as noise and ship strikes.
“What we found was surprising: a really high number of daily plastic ingestions,” said Dr. Shirel Kahane-Rapport, of California State University, Fullerton, who led the study. “We imagine it will have some sort of impact, but we don’t know the exact health effects. This is the first step to understand it “.
There are far more polluted ocean basins in the world than the California coast, Kahane-Rapport said, including the North Sea, the Mediterranean, and Southeast Asian waters. “The whales that feed in those areas could certainly be more at risk than off the coast here in the western United States,” said Dr. Matthew Savoca, of Stanford University, who was part of the team that conducted the study.
“It’s a sad story about whales, but it’s also a story about us,” said Savoca, as human diets are also affected. “Whether it’s cod, salmon or other fish, they’re eating the same fish that humpback whales eat.”
Huge amounts of plastic waste are dumped into the environment and microplastics have polluted the entire planet, from the summit of Everest to the deepest oceans. At least 1,500 wild species have been reported to ingest plastic. People consume the tiny particles through food and water and inhale them. In March it was revealed that microplastics are present in human blood.
The research, published in the journal Nature Communications, combines a series of measurements to estimate whale consumption of microplastics. The tags on 191 blue, fin and humpback whales recorded more than 36,000 whale feeding lunges, and airborne drones were used to measure the amount of water captured by each lunge.
The density of the prey in the water was assessed using acoustic devices and the microplastic in the prey was estimated using previous research and measurements of plastic pollution in the water column. Scientists have found that baleen mainly feed at depths of 50-250 meters, which is also where most microplastics are found.
Humpback whales, which are smaller than blue whales, are estimated to ingest up to 4 million microplastics per day when they feed on krill and 200,000 particles when they feed on fish, such as anchovies.
The researchers believe their estimates are conservative, as plastic pollution will have increased since the data was collected and made conservative estimates of how much plastic prey krill and fish species consume.