If ocean pollution means fish are eating plastic, aren't we eating it too?

Yet more plastic litter has been discovered in the Mariana Trench, raising questions about our food safety

15 May 2019 - 14:01 By Sanet Oberholzer
Could the fish and seafood that end up on your dining table have consumed plastic while in the ocean?
Could the fish and seafood that end up on your dining table have consumed plastic while in the ocean?
Image: iStock

It seems everywhere you turn new-wave reusable straws made from metal or bamboo are being sold: at markets, quirky shops, online. They're being punted as the solution to stopping the millions of plastic straws that end up polluting ours seas.

In fact, many restaurants have stopped serving drinks with plastic straws all together.

If this hype around plastic straws seems to be over the top, chew on this for a moment: in the Mariana Trench, the lowest point in the ocean, signs of plastic pollution have been found — not once but three times.

On April 28 American businessman, Victor Vescovo, embarked on an expedition to dive into the Mariana Trench where the distance between the surface of the ocean and its deepest point is 11km.

His findings have just been made public. During the four hours Vescovo spent at the bottom of the Mariana Trench, apart from the unique marine creatures he saw, he found a plastic bag and sweet wrappers — the latest in a list of plastic particles found at these depths. 

In a study conducted in 2018, scientists found that plastic was the most prevalent pollutant logged in a database of photos and videos taken by deep-sea submersibles and remotely operated vehicles in the world’s oceans over the last 30 years. They too discovered a plastic bag in the Mariana Trench.

Research published in the peer-reviewed journal Royal Society Open Science earlier this year found that all of the organisms in the Mariana Trench on which scientists conducted tests had consumed plastic and exhibited signs of plastic pollution.

The team’s findings revealed that over 72% of amphipods — scavenger relatives of crabs and shrimp — contained at least one micro-particle of plastic. Some of the organisms had ingested as many as eight particles.

These weren’t just any kind of plastic: they were human-made pollutants such as polychlorinated biphenyls that have been banned for decades but have a very long shelf life in nature.

While amphipods will eat just about anything they can lay claim to, shrimp and fish eat amphipods. When fish die, the amphipods eat them and so the cycle continues. It isn’t difficult to reach the conclusion that, sometimes, humans eat these very same shrimp and fish.

Perhaps the plastic straws we discard without a second thought aren’t the source of the problem in these specific instances, but this problem does speak to the bigger issue of plastic pollution.

Perhaps you don’t see the effects of plastic pollution in the ocean first-hand and can shrug off responsibility when you read of its extent. You are also not the one being forced to consume plastic-contaminated fish — for now. But the question begs to be answered: if we continue along this trend, how long before we are all being served plastic-flavoured trout?