A 56-foot long, 120,000-pound sperm whale that washed ashore dead on the coastline of Kauai Jan. 27 likely died from ingesting fishing net, plastics and other marine debris, University of Hawaii scientists said Thursday. It’s ugly proof of the threat to marine life posed by the ocean’s saturation with plastic, trash and fishing gear.

Sperm whales, listed as endangered under the Endangered Species Act since 1970, are considered in danger of extinction. They have been termed a “sentinel species” by conservationists, as the whales’ well-being — or lack of it — as a species reflects the ocean’s health as a habitat.