"It's very disgusting and heartbreaking," he told AFP.
"We've done necropsies on 61 dolphins and whales in the last 10 years and this is one of the biggest (amounts of plastic) we've seen."
The 4.7m-long whale was stranded in Mabini town where people tried to release it, only for the creature to return to shallow water.
"It could not swim on its own, emaciated and weak," regional director of the bureau of Fisheries and Aquatic Resources Fatma Idris told AFP. "(The) animal was dehydrated. On the second day it struggled and vomited blood."
The Global Alliance for Incinerator Alternative, in a report on single-use plastic in the Philippines, said nearly 60 billion sachets a year were released.
The Philippines has strict laws on rubbish disposal but environmentalists say these are poorly implemented.
The problem occurs in neighbours. A sperm whale died in Indonesia last year with nearly 6kg of plastic in its stomach.
A whale also died last year in Thailand after swallowing more than 80 plastic bags. A green turtle suffered the same fate there in 2018.