The research, conducted by the University of Adelaide, found microplastic fragments in 49 percent of fish.
Chief researcher Nina Wootton of the School of Biological Sciences at the University of Adelaide said many commercial and recreational fishermen were unaware of the scale of the problem.
“We wanted to find out what people knew about microplastic pollution in fish, from fishermen to fishmongers to consumers,” she said in a statement.
“It varied, but about half didn’t realize it was a problem because South Australia’s oceans had such a reputation for being clean.”
There was three times as much plastic in fish from international waters, Ms. Wootton added.
Researchers are now working together with the seafood industry to educate fishermen and the community on how to reduce plastic waste.
“We still have time to make sure Australian seafood remains some of the cleanest in the world, but we need the seafood industries and the general public to recognize the problem and start taking positive action now,” she said.