The Incidence Of Plastic Ingestion By Fishes

This study investigates what percentage of plastic items are apparently bitten by fish or sharks as well as the size of fish who bite plastic and whether bitten items have particular characteristics. Hard plastic debris was collected from randomly selected plots on a Hawai’ian beach. Bitten items were recorded as a percentage of all items by count (15.8%) and by weight (17.3%). Items that were blue, yellow, or bottle-shaped were most frequently bitten. There was a wide range of bite-mark sizes, indicating engagement by a variety of species and/or those at varied stages of growth.

“One of the primary threats to ocean ecosystems from plastic pollution is ingestion by marine organisms. Well-documented in seabirds, turtles, and marine mammals, ingestion by fish and sharks has received less attention until recently. We suggest that fishes of a variety of sizes attack drifting plastic with high frequency, as evidenced by the apparent bite marks commonly left behind. We examined 5518 plastic items from random plots on Kamilo Point, Hawai’i Island, and found 15.8% to have obvious signs of attack. Extrapolated to the entire amount of debris removed from the 15 km area, over 1.3 tons of plastic is attacked each year. Items with a bottle shape, or those blue or yellow in color, were attacked with a higher frequency. The triangular edges or punctures left by teeth ranged from 1 to 20 mm in width suggesting a variety of species attack plastic items. More research is needed to document the specific fishes and rates of plastic ingestion.”