About 23% of stranded short-finned pilot whales throughout a 13-year time period in the main Hawaiian Islands ingested several pounds of essentially trash — discarded plastic ropes, netting, fishing gear and plastic bags — in ocean waters.
University of Hawaiʻi at Mānoa researchers in a new study published in Marine Pollution Bulletin examined stomachs and digestive tracts of 13 stranded short-finned pilot whales.
Necropsies of 3 adult males — post-mortem examinations and dissections of the animals’ bodies — revealed large masses of tangled plastic inside their stomachs.
Recovered debris was estimated at 4 to 12 pounds per whale, yielding a staggering 6,283 to 35,543 distinct plastic pieces larger than 5 millimeters in size — about the width of a standard pencil eraser — per individual.
“The presence of human-made materials in the stomachs of these ocean sentinels serves as a stark reminder of the impact of global plastic pollution,” said study corresponding author University of Hawaiʻi Health and Stranding Lab Director Kristi West in a university release. “It is a clear message of the importance of keeping these materials out of our ocean.”
Debris was primarily abandoned, lost or otherwise discarded fishing gear, such as monofilament lines, ropes and netting.
Sheet plastics, including garbage or carrier bags, were the next most common items. Plastic longer than 200 millimeters in size — or about 8 inches, near the length of an iPad — contributed more than 70% of the overall debris weight in all three whales.
Pilot whales in Hawaiʻi waters were found to be highly vulnerable to ingesting marine debris.
A squid diet and proximity of the Hawaiian Islands to the Great Pacific Garbage Patch, located northeast of the archipelago, might increase the risk of marine debris ingestion by the pilot whales.
While the whales exhibited normal body conditions and debris was not identified as direct cause of death, researchers warned plastics cause nutritional stress and have toxic chemicals that accumulate in whale and dolphin tissues.
Data collection spanned 7 years, was supported by 25 lab members and received funding from the Commander, United States Pacific Fleet, Environmental Readiness Division and National Oceanic and Atmospheric Administration Fisheries Prescott Grant program.
The study was led by University of Hawaiʻi Health and Stranding Lab within the College of Tropical Agriculture and Human Resilience.
