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Getting questions about @seaspiracy and the stat that 46% of plastic in the Great Pacific Garbage Patch is fishing nets.
I can confirm this is true - I am a co-author of that study.
Yet this doesn& #39;t necessarily mean that 46% of what enters the oceans is from fishing [THREAD
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I can confirm this is true - I am a co-author of that study.
Yet this doesn& #39;t necessarily mean that 46% of what enters the oceans is from fishing [THREAD
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In the Great Pacific Garbage Patch (GPGP) we observe a very specific composition of trash: almost everything is & #39;thick& #39; plastic. You see buoys, bottles and toothbrushes, but hardly any plastic bags or other household packaging (while this is the dominant type in river trash).
Compare the composition of trash from a river (left) and the GPGP (right). Very different stuff!
The plastic in the GPGP is on average decades old. Packaging waste, most of it being & #39;thin& #39;, is likely to fragment into microplastics in that timespan, or sink because its high surface-to-volume ratio means it& #39;s not very buoyant.
Fishing gear, however, is mostly & #39;thick& #39; - look at buoys, crates and nets. This trash fragments much more slowly and is also very buoyant; prime candidates to hang around in the GPGP.
And there& #39;s another thing: consumer waste comes from rivers, so enters the ocean right next to the coast. Our models indicate that, for plastic coming from rivers, 97% ends up back on shore within a year of entering the oceans due to wind and waves.
To break loose of coastlines and end up in the GPGP, you have to be a pretty lucky piece of plastic! Fishing gear, however, tends go get lost far away from the coast, so has a much higher chance of ending up in the GPGP.
In other words, there are likely selection effects, which give a distorted picture in the GPGP. 46% of plastic in the GPGP does not mean 46% of the source is fishing boats. In coastal waters, most plastic is from rivers.
So how much of the source is fishing? Nobody knows for sure, and it& #39;s something we& #39;ve been trying to find out, but it& #39;s easier said than done. For one, we find many fishing companies are reluctant to share data with us on gear loss.
It is often estimated that 80% comes from land (rivers) and 20% from maritime sources (fishing and boats). I wouldn& #39;t be surprised if this turns out to be a reasonable estimate. But we aim to refine this.
All of this doesn& #39;t refute the point the documentary made: lost/discarded fishing gear is very harmful, and an important source of ocean trash. But it& #39;s not the only source, and it& #39;s no reason to stop focussing on rivers (next to cleaning up the GPGP).
For the full @TheOceanCleanup study mapping the GPGP, see our 2018 paper here: https://www.nature.com/articles/s41598-018-22939-w">https://www.nature.com/articles/...
