New Study Shows Larval Fish Are Eating Our Trash

Scribbled filefish in a sea of plastics

A new study on the Pacific Ocean’s floating trash indicates not only a significant accumulation of microplastics in the Hawaiian Islands, but that larval fish are eating the debris.  

The research, conducted in partnership with Hawaiʻi Pacific University’s Center for Marine Debris Research (CMDR), centered on waters off the Kona coastline of Hawaiʻi Island. The area is found to accumulate microplastic pollution at a rate higher than the North Pacific Garbage Patch itself, and the larval fish living in this nursery habitat are eating the trash that surrounds them. 

The findings are published in the journal, Proceedings of the National Academy of Sciences

The National Oceanic and Atmospheric Administration (NOAA) sampled surface waters near West Hawaiʻi using plankton tows with the intention of learning about the larval fish community in that nursery habitat.  It was no surprise that the researchers found young fish of many different types, including species that are gathered for commercial or recreational fisheries and that also play vital roles in ecosystems, such as Hawaiian coral reefs.  

“But we were shocked to find that so many of our samples were dominated by plastics,” said Jonathan Whitney, a marine ecologist for NOAA and co-lead of the study.  Within the slicks—small-scale convergence zones that look like ribbons of smooth water—plastic particles outnumbered larval fish seven to one. The concentration of plastic per square kilometer in the surface water slicks off of West Hawai‘i was eight times greater than in the North Pacific Garbage Patch.  

“The North Pacific Garbage Patch is known as one of the most plastic-polluted marine waters on earth. It is deeply concerning that concentrations in these hotspots in Hawai‘i exceed those in the Garbage Patch,” said Jennifer Lynch, research biologist with the National Institute of Standards and Technology and co-director of the HPU CMDR. 

HPU’s CMDR determined the chemical composition of the plastic found in the tows, outside of the fish, to be mostly polyethylene and polypropylene. Next, the researchers dissected the digestive tracts of the tiny fish under a microscope. 

 “We found tiny plastic pieces in the stomachs of commercially targeted pelagic species, including swordfish and mahi-mahi, as well as in coral reef species like triggerfish,” said Whitney.  Most of the particles were microfibers. 

Lynch identified the chemical composition of the fibers to prove that they were man-made.  Two different types of chemical spectroscopy, Fourier-transform infrared and Raman, revealed that some were polyester, nylon, or rayon, and most were dyed cellulose, which could come from cotton fabric. 

 “The fact that larval fish are surrounded by and ingesting non-nutritious toxin-laden plastics, at their most vulnerable life-history stage, is cause for alarm,” explained Jamison Gove, a research oceanographer for NOAA and co-lead of the study. 

“The multiple, disturbing discoveries in this study spotlight the negative impact humans are having on our planet.  We can make changes to reduce our impact, and these changes are needed now,” said Lynch.  

The CMDR’s goal is to help eliminate plastic waste from the ocean, and the team is deeply committed to diving into this issue, right here in Hawaiʻi. The Center continues to strive to move conversations forward about creating a trash-free ocean environment, while investigating the impacts of marine debris and distributing the knowledge of clean ocean awareness initiatives and stewardship. 

The publication is titled “Prey-size plastics are invading larval fish nurseries” and is published in Proceedings of the National Academy of Sciences

Pictured is a scribbled filefish in a sea of plastics sampled in surface slicks off Hawai‘i Island. Photograph courtesy of David Liittschwager