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Trawl nets or vacuum cleaners are intended to clear the oceans of plastic waste. That sounds good. In fact, the cleaning methods are harmful – especially for the animals in the sea.
Nobody can say exactly how much plastic waste is floating around in our seas, says Lars Gutow, marine biologist at the Alfred Wegener Institute in Bremerhaven. But the magnitude is clear: it’s millions of tons.
This is bad: crabs, turtles and whales can swallow plastic particles. If they have too much of these particles in their stomachs, but they don’t provide them with energy, they can starve. Another danger is lost fishing nets, so-called ghost nets, in which animals get caught.
Unintentionally captured organisms
The obvious solution: pick up the trash. But as simple as it may sound, it is not: “If you really want to get substantial amounts out of the oceans, you need methods that are not picky, so to speak. With these, it is practically unavoidable that a lot of biological material is removed at the same time,” says Gutow.
If Ocean Cleanup really wants to efficiently remove as much plastic as they originally promised, then they will have to significantly intensify their collection.
Small crabs, for example, which are transported by the ocean currents just like plastic waste and therefore accumulate in the same places. But also larger animals: fish, sharks, squid and turtles. They cavort there because they are attracted to the small animals – their food.
Plastic waste is teeming with creatures that are then unintentionally caught. For example with nets that pull ships behind them. A prominent example of this is an initiative from the Netherlands, The Ocean Cleanup. As the organization itself writes, the numbers are low: For almost 200,000 kilograms of plastic, there were a little less than 700 kilograms of bycatchi.e. unintentionally caught organisms. But: “If Ocean Cleanup really wants to efficiently remove as much plastic as they originally promised, then they have to significantly intensify their collection,” says Gutow. Inevitably the numbers of bycatch also increase.
Collect carefully by hand
So should you let plastic lie or float? “Not necessarily,” says Lars Gutow. It is simply important that you collect in a targeted manner, rather than with a large trowel, so that it causes as little damage to the environment as possible. Ghost nets in particular are a good example of this: they can be detected on the seabed using sound waves, and divers can then recover them.
Another gentle method: collect by hand. Actions on beaches are an example of this. But: “The quantities that are collected in this way are very manageable,” says Gutow.
What is the lesser evil?
It’s a dilemma: On the one hand, technological methods that could collect large quantities but are bad for the animals. And on the other hand, selective actions that are gentle, but at the same time more like a drop in the ocean.
«It’s a dilemma“that cannot be solved,” says Gutow. But we still don’t have to put up with all the rubbish in the sea. Just start at the other end: “We have to stop pumping this material into the oceans.” That is the most effective thing.