More than 800 species of marine animals are susceptible to the estimated 8.8 million tons of plastics deposited each year in the ocean, Mr. Mallos said, and often in ways that do not lead to graphic imagery like the whale in Indonesia. Plastics can entangle and trap animals, sometimes causing them to drown, or pierce elements of their digestive systems after being swallowed.

“What is concerning is that the likelihood of these types of interactions, and these types of horrific encounters between marine organisms and plastic debris, is only likely to continue unless some drastic measures are taken,” Mr. Mallos said.

In 2010, the top six plastic waste producers were in or near Southeast Asia: China, Indonesia, the Philippines, Vietnam, Sri Lanka and Thailand. Much of the waste comes in the form of single-use items that do not decompose like bags, food packaging, straws and cutlery. The European Parliament voted to ban such items in October, with the ban taking effect in 2021.

While Indonesia outpaces much of the world in plastic use, there are efforts underway to curb it. The country has set a goal of reducing plastic waste by 70 percent by 2025, setting aside $1 billion per year to combat the problem. In one effort to increase recycling, residents of Surabaya, the country’s second-largest city, can pay their bus fare by recycling 10 plastic cups or up to five plastic bottles.