Larval fish off the coast of Kona are eating plastics at an alarming rate, according to a study published Monday in a national scientific journal.
The study — conducted by Hawaii Pacific University and the National Oceanic and Atmospheric Administration — found that 8.6% of larval fish found off Hawaii Island’s west coast had ingested microscopic plastic materials, or microplastics.
The 19 authors of the study selected a region off the Kona Coast that is home to surface slicks, where small-scale currents draw fish and other matter together. The slicks that were studied were found to have a greater concentration of plastic than in the Great Pacific Garbage Patch.
“What’s interesting is that the fish that we studied are surrounded by plastic of a different type from what they’re eating,” said Jennifer Lynch, one of the study’s authors.
Lynch, co-director of HPU’s Center for Marine Debris Research as well as a research biologist with the National Institute of Standards and Technology, said the fish studied were largely eating microscopic fibers theorized to come from everyday laundry.
“We found cotton fibers that had man-made dye and also fibers of polyester, rayon and nylon,” Lynch said. “And all of those are what clothes are commonly made out of.”
Clothes shed microfibers naturally during the washing process, Lynch said — dryer lint is actually an accumulation of microfibers and other materials. But fibers dislodged by a washing machine can be too small to be adequately filtered out and enter the ocean — and, ultimately, a fish.
“The plastics are the same size as (the fish’s) prey,” Lynch said. “So you can imagine a fish thinking, ‘I’m hungry, there’s something floating there, it must be food.’”
Lynch said the study did not focus on the specific health effects caused by the fishes’ diet, but added that, based on other studies, fish habitually eating plastic could be expected to grow more slowly because they are still being satiated by “food” with no nutritional value.
In order to survive, fish in their larval stage must grow “as fast as they should,” Lynch said, because larger fish are less likely to be eaten by even bigger fish. Therefore, fish whose growth is stunted by plastic consumption have a worse survival rate than fish with a normal diet. And because the fish studied include commercially harvested fish such as swordfish and mahi-mahi, fewer fish reaching adulthood could have wide-reaching effects.
Other fish studied included triggerfish and flying fish. The latter are particularly prone to eating plastic, Lynch said, and often are prey for tuna and seabirds, thus transferring the plastics to other animals.
Lynch also suggested chemical additives in plastic could be transferred to humans eating plastic-contaminated fish, but emphasized there is not yet enough data to conclude any health effects on humans from eating such fish.
Lynch said there are some ways for people to reduce microfiber waste. The simplest is installing filters on washing machines to keep microfibers out of wastewater. Filters designed for this purpose are commercially available.
Email Michael Brestovansky at mbrestovansky@hawaiitribune-herald.com.