A recent study published on June 27 in the journal Marine Ecology Progress Series found plastic in the stomachs of nine percent of fishes living in the “Great Pacific Garbage Patch.” The study was completed by a group of graduate students from Scripps Institution of Oceanography at UC San Diego.
Two graduate students, Peter Davison and Rebecca Asch, with the Scripps Environmental Accumulation of Plastic Expedition (SEAPLEX) collected fish from the North Pacific Subtropical Gyre. They estimated that the fish in intermediate ocean depths of the North Pacific ingest plastic at a rate of 12,000 to 24,000 tons per year.
During the SEAPLEX voyage in August 2009, a team of graduate students traveled over 1,000 miles to the eastern sector of the North Pacific Subtropical Gyre on the Scripps research vessel New Horizon. During this 20 voyage, they collected 141 fish specimens of 27 different species, water samples and marine debris at depths ranging from the surface to thousands of feet below.
When dissecting the specimens, they found that 9.2 percent of the mid-water fishes contained plastic debris, most of which was broken-down and smaller than a human fingernail–so small that they could not determine the origin of the pieces.
“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.
The majority of the fish in the study were lanternfish (myctophids) who live between a depth of 200 to 1,000 meters during the day and swim to the surface at night.
“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.
Since the “great garbage patch” isn’t actually a patch or an island, it cannot be mapped from above. The researchres collected samples across a distance of over 2,375 km (1,700 miles) in order to locate the boundaries of the patch.
“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. Leichter participated in the study but was not an author of the paper.
“We are seeing that most of our prior predictions and expectations about potential impacts have been based on speculation rather than evidence and in many cases we have in fact underestimated the magnitude of effects,” said Leichter. “SEAPLEX also clearly illustrates how relatively small amounts of funding directed for novel field sampling and work in remote places can vastly increase our knowledge and understanding of environmental problems.”
Take a look at this article to learn more about the garbage patch.
Copyright © 2011 by Marine Science Today, a publication of OceanLines LLC