Study Shows Larval Fish Are Ingesting Plastics

A new study released by the University of Hawaii at Manoa shows that larval fish species from different ocean areas are ingesting plastics in their preferred nursery habitat.

The study, conducted by NOAA’s Pacific Islands Fisheries Science Center and an international team of scientists, concluded that the further investigation is needed to understand the effects of plastic ingestion by larval fish on individuals and populations.

Researchers combined field-based plankton tow surveys and advanced remote sensing techniques to identify larval fish nursery habitats in coastal waters of Hawaii for their study, which was published on Nov. 11 in the journal Proceedings of the National Academy of Sciences. The study was also reported on EurekAlert, the online publication of the American Association for the Advancement of Science.

Researchers found that surface slicks –naturally occurring, ribbon-like, smooth water features at the ocean surface – contained far more larval fish than neighboring surface waters. The surface slicks are formed when internal ocean waves converge near coastlines. They are observed in coastal marine ecosystems worldwide. These slicks also aggregate plankton an important food source for larval fish.

”We found that surface slicks contained larval fish from a wide range of ocean habitats, from shallow-water coral reefs to the open ocean and down into the deep sea – at no other point during their lives do these fish share an ocean habitat in this way” said Jonathan Whitney, a marine ecologist for the Joint Institute for Marine and Atmospheric research and NOAA, and a co-lead of the study. “Slick nurseries also concentrate lots of planktonic prey, and thereby provide an oasis of food that is critical for larval fish development and survival.”

Larval fish in these surface slicks were found to be larger, well developed and having increased swimming abilities, but researchers noted that plastic densities in these surface slicks were on average eight times higher than the plastic densities recently found in the Great Pacific Garbage Patch. In fact, there were seven times more plastics than there were larval fish, and most were less than one millimeter is size. Plastics were also found in flying fish, which apex predators such as tunas and most Hawaiian seabirds eat.

Tiny plastic pieces were also found in the stomachs of commercially targeted pelagic species, including swordfish and mahi-mahi, as well as coral reef species like triggerfish, Whitney said.