The body of the 56 foot (17 metre) long, 120,000-pound (54,431 kilogram) sperm whale was first noticed on a reef off Kauai, before it was washed ashore last week.
The whale's stomach contained six hagfish traps, seven types of fishing net, two types of plastic bags, a light protector, fishing line, and a float from a net.
Kristi West, the director of the University of Hawaii's Health and Stranding Lab, said there were enough foreign objects in the opening of the whale's intestinal tract to block food.
“The presence of undigested fish and squid lends further evidence of a blockage,” she said in a news release from the Hawaii Department of Land and Natural Resources.
It’s the first known case of a sperm whale in Hawaii waters ingesting discarded fishing gear, Mrs West said.
Scientists say that more than 35 million tons (31.9 million metric tons) of plastic pollution is produced around the planet each year, and about a quarter of that ends in the ocean.
In addition to eating plastics, large whales are harmed when they become entangled in fishing gear or other ropes in the ocean.
The drag from debris can force whales to use more energy to swim and make it harder for them to eat, causing starvation.
Researchers also found squid beaks, fish skeleton and remains of other prey in the whale's stomach.
Sperm whales can travel across thousands of miles in the ocean so it’s not clear where the debris came from.
Despite the blockage, the scientists found there to be nothing wrong with other organs they examined.
Sperm whales are an endangered species found in deep oceans across the world.
A 2021 report from the National Oceanic and Atmospheric Administration estimated there were about 4,500 sperm whales in the waters around the Hawaiian Islands, from the Big Island in the south to Kure Atoll in the north.
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