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Plastic ingestion by fish a growing problem

Picture of a plastic bag under water.

Leopard sharks off southern California swim in shallow water surrounded by marine debris.

Ralph Pace
Feb 10 2021

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The consumption of plastic by marine animals is an increasingly pervasive problem, with litter turning up in the bellies of wildlife as varied as mammals, birds, turtles and fish. However, according to a research review by ecologists at Stanford University’s Hopkins Marine Station and PhD student Alex McInturf at UC Davis, the problem is impacting species unevenly, with some more susceptible to eating a plastic dinner than others. With billions of people around the world relying on seafood for sustenance and financial security, this research, published Feb 9. in the journal Global Change Biology, warns that there is a growing number of species – including over 200 species of commercial importance – eating plastic.

Matthew Savoca was collecting data on plastic ingestion by seabirds for his PhD when he became interested in uncovering ecological traits linked to increased consumption. Now, as a postdoctoral research fellow at the Hopkins Marine Station, he has conducted one of the most comprehensive analyses of plastic ingestion on fish ever performed.

“Fish are a really good species to track the flow of plastic pollution through marine ecosystems,” said Savoca, who is lead author of the paper. “Now, we are showing the numbers in ways they haven’t been shown before. No previous studies have looked across all of this research for broad patterns and drivers.”

Savoca and his team collected all the data they could find from scientific literature related to plastic ingestion by fish. In total, they reviewed 129 studies on 171,774 individuals of 555 species of marine fish. When he first began this endeavor roughly a decade ago, he was surprised how little data was available. However, over the last few years, Savoca said, the number of studies has “gone through the roof.”

The team’s database reveals the consumption of plastic by fish is widespread and increasing. Over the last decade, the rate of plastic consumption has doubled, increasing by 2.4 percent every year. Part of this is due to scientists’ increasing ability to detect smaller particles of plastic than before.

“Don’t panic, because unlike other environmental issues, we have an impassioned public movement to do something about it,” said Savoca. “This is half the battle, but we must keep it going.”

Although this is one of the most comprehensive analyses to date about plastic consumption by fish, a significant portion of the ocean has yet to be studied. This includes ocean gyres, where most plastic pollution ends up, as well as polar regions. Studying these difficult-to-access regions, said Savoca, will be important for filling gaps in our knowledge.