Worried that people eat too much junk food? At least they’re not fish in the Pacific Ocean that eat actual junk.

A new study by two graduate students from the Scripps Institution of Oceanography at UC San Diego found that a little over nine percent of the fish that swim near the Great Pacific Garbage Patch ingest roughly 12,000 to 24,000 tons of plastic a year.

Peter Davison and Rebecca Asch traveled 1,000 miles west of California to the eastern sector of the North Pacific Subtropical Gyre. Over the next 20 days, they and a team of fellow graduate students collected fish, water and debris specimens from various locations in the ocean.

As the 141 fish from 27 species were dissected and analyzed, Davison and Asch discovered that 9.2 percent of the fish has tiny particles of plastic debris in their stomachs.

"About nine percent of examined fishes contained plastic in their stomach. That is an underestimate of the true ingestion rate because a fish may regurgitate or pass a plastic item, or even die from eating it. We didn't measure those rates, so our nine percent figure is too low by an unknown amount," said Davison.

Lanternfish studied

Many of the fish collected in the sample were lanternfish, named such because of their luminescent tissue.

Lanternfishes are thought to use luminescence for multiple reasons, including counter-illumination, attracting mates and identification and illumination of prey.

"These fish have an important role in the food chain because they connect plankton at the base of the food chain with higher levels. We have estimated the incidence at which plastic is entering the food chain and I think there are potential impacts, but what those impacts are will take more research," said Asch.

The effects the ingestion of plastic had on the fish were outside the goals of the study.

Marine debris is difficult to map from air or space, and as such the crew of the expedition collected samples of water across a distance of over 1,700 to find the boundaries of the garbage patch.

Area of study

The specific area the study collected its data from, the North Pacific Subtropical Gyre, is largely untraveled by boats, and understudied by scientists, making it an ideal location for the study.

"This study clearly emphasizes the importance of directly sampling in the environment where the impacts may be occurring," said James Leichter, a Scripps associate professor of biological oceanography who was not associated with the study.

The Scripps Environmental Accumulation of Plastic Expedition was supported by the UC Ship Funds program, Project Kaisei/Ocean Voyages Institute and the National Science Foundation.

The study was published June 27 in the journal Marine Ecology Progress Series.