Hawaiian Pilot Whales Were Found With Pounds of Plastic in Their Stomachs

Short-finned pilot whales found stranded around Hawaiʻi had swallowed substantial amounts of discarded plastic and fishing equipment, according to a study by researchers at the University of Hawaiʻi at Mānoa. The research examined the stomachs and digestive tracts of 13 stranded whales from the main Hawaiian Islands. Across the 2010–2023 period covered by the study, nearly 23% of stranded short-finned pilot whales were found to have ingested marine debris. Necropsies of three adult males revealed masses of tangled material inside their stomachs. The debris included monofilament fishing lines, ropes, netting and other abandoned, lost or discarded fishing gear. Plastic sheets, including garbage and carrier bags, were the next most common category. Researchers estimated that each of the three whales had consumed between 4 and 12 pounds of debris. The material amounted to an estimated 6,283 to 35,543 individual plastic pieces larger than 5 millimeters per whale. Pieces longer than 200 millimeters accounted for more than 70% of the debris’ combined weight in the three animals. The whales were reported to be in normal body condition, and the study did not identify the debris as the direct cause of death. Researchers nevertheless warned that swallowed plastic may contribute to nutritional stress and may expose whales to toxic chemicals that can accumulate in the tissues of whales and dolphins. The study’s authors identified pilot whales in Hawaiʻi as especially vulnerable to ingesting marine debris. Their squid-based diet and the islands’ proximity to the Great Pacific Garbage Patch, located northeast of the archipelago, may increase the risk, according to the research. The findings, published in Marine Pollution Bulletin, were led by the University of Hawaiʻi Health and Stranding Lab. The researchers said the debris found in these animals demonstrates the effects of plastic pollution and the importance of preventing fishing gear and other plastic materials from entering the ocean.