If you have been reading my recent posts, you have noticed that I have been discussing the emerging science on plastic pollution in the ocean and exploring what we need to do to stem the tide. It started in February, when a groundbreaking study showed that 8 million tons (nearly 17 billion pounds) of plastic flows into the ocean each year, mostly from a small number of Asian nations where local waste management can’t keep up with rapidly growing plastic use. Then scientists estimated that nearly all the worlds’ seabirds will be contaminated by plastics by 2050 unless conditions don’t change. And a study published only days later showed that half the globe’s sea turtles are likely to suffer the same fate. Today, we need to think carefully about the latest study, showing that plastics can be found in many of the fish that we eat. We don’t yet know if eating plastic-laden fish negatively impacts our health, but today’s study is another brick in the growing wall of scientific evidence that demonstrates that plastics are a major threat to the global ocean and ultimately, ourselves.
Roughly a quarter of fish sampled from fish markets in California and Indonesia contained manmade debris—plastic or fibrous material—in their guts, according to a new study by Dr. Chelsea Rochman from the University of California, Davis and colleagues from Hasanuddin University in Indonesia. The study, published today in the journal Scientific Reports, is one of the first to directly link plastic and man-made debris to the fish on consumers’ dinner plates. The researchers sampled 76 fish from markets in Makassar, Indonesia and 64 from Half Moon Bay in California. All of the manmade fragments recovered from fish in Indonesia were plastic. In contrast, 80% of the debris found in California fish was fibers while not a single strand of fiber was found in the Indonesian fish.
These patterns appear to be related to differences in waste management in the two countries. Indonesia has little in the way of landfills, waste collection or recycling, and large amounts of plastic are tossed onto the beaches and into the ocean and waterways. Meanwhile, the U.S. has relatively advanced systems for collecting and recycling plastics. Indonesia ranks second for mismanaged waste globally, producing ten times more mismanaged waste than the twentieth ranked United States. In contrast, most Californians wash their clothing in washing machines, the concentrated wastewater from which then empties into the ocean from more than 200 wastewater treatment plants along the coast. Rochman theorizes that fibers remaining in sewage effluent from washing machines were ingested by fish swimming offshore of the state.
So now we know that plastics are in the fish that we eat, fish like anchovy, rockfish, striped bass, Chinook salmon, sanddab, lingcod and oysters. What we don’t yet know is whether this puts our health at risk. But there is growing cause for concern. Scientists have shown that plastics contain a range of hazardous chemicals that are used during their production and also adsorb toxic chemicals once they reach the ocean. There is evidence that some of these chemicals can become bioavailable to a range of species from lugworms to seabirds to fish. Rochman and her colleagues conclude that “chemicals from anthropogenic debris may be transferring to humans via diets containing fish and shellfish, raising important questions regarding the bio-accumulation and bio-magnification of chemicals and consequences for human health.” Clearly more research is needed to quantify these risks and weigh any risk against the other well-known benefits of consuming seafood.
At Ocean Conservancy, we are committed to stopping plastics from getting into the ocean in the first place. If we can keep the ocean clean, we can keep plastics out of our seafood – and ourselves.