This shocking video released by the Alaska Department of Fish and Game shows the horrifying pain and, often, fatal injuries a tiny piece of man-made debris – a plastic bottle, say, or a fishing net – can cause to sea lions.

Thousands of animals die every year after swallowing or getting entangled in this environmental waste. Since the late 1970s, the population of Steller sea lions in western Alaska has fallen by over 80%:

This is not an isolated problem. It takes every plastic bottle thrown into the sea no less than 450 years to decompose; for a glass bottle, it's a million years. In a recent study, nearly half of all the animals found by Alaska's Steller sea lion programme had picked up some marine debris. One lucky male sea lion, found with a tyre around his neck, survived; others were less fortunate.

But as the video shows, the problem is solvable – and fixing it would benefit humans too. Simple measures like cutting up rope before disposing of it, and not throwing waste into the sea, would save hundreds of sea lions from painful injury and death; but they would also cost fishermen less in valuable equipment and lost catches too.

Take action: Donate or volunteer to help the Marine Mammal Center educate the world about sea mammals and inspire their conservation.