When Lewis Pugh set out to swim the Seven Seas, he was doing it to raise awareness about the state of our oceans. However, he wasn’t prepared for just how bad it was.
Swimming through parts of the Red Sea, he compared it to an “underwater desert”, with no sign of sea life at all. This is unsurprising, considering the amount of overfishing and trawling that happens.
What is bottom trawling?
Bottom trawling uses large nets to commercially catch large amounts of marine life found near or on the seafloor. These nets are held open and weighted down by heavy doors that may be up to 40 feet tall. Trawl nets can cover an area half an acre wide in one pass, and are used in deep waters or on continental shelves and slopes.
Below is a video of a bottom-trawl net in action:
What are the impacts?
World-wide, an area approximately the size of the contiguous U.S. is trawled twice over each year, decimating the seafloor. Comparable to terrestrial clear-cutting, it completely removes vital habitats by levelling corals, rock beds, seamounts, and other features. Trawling also raises huge sediment plumes that can be seen from space, affecting light attenuation and water quality.
Economically, bottom trawling is of minor importance, contributing to less than 1% of the reported total marine fish catch. 75% of the world’s fisheries are overfished and the indiscriminate capture of everything in its path means that species interactions and habitat structure are altered.
A 2014 report by Oceana estimates that the U.S. alone discards $1 billion worth of bycatch–or non-target species–annually, tossing them back overboard, dead or dying. This dumping occurs because these species or those that have been fished to the limit must be tossed to remain within quota, even though they are acceptable for consumption. Seabirds, turtles, and marine mammals are often inadvertently caught as well, contributing to biodiversity reduction.
What can be done?
The best way to return productivity and diversity to these ocean floor habitats is to completely halt trawling activities. Unfortunately, as the EU demonstrated last year, a complete ban on the most destructive fishing practices is difficult to pass.
We can attempt to reduce and regulate trawling in marine ecosystems by increasing no-take Marine Protected Areas (MPAs), which is a geographical space protected for the long term conservation of nature with associated ecological and cultural importance. MPAs would stop the practice of bottom trawling in that area, and could have huge benefits. They increase biodiversity, allow ecosystems to recover from and resist disturbance, and provide marine-related tourism.
It was only when Lewis Pugh swam through a MPA in the Red Sea that he “experienced a sea as it was meant to be: rich and colourful and teaming with abundant life”.
Small-scale fishing would also be another viable option, as it uses low-impact gear, often attracting sustainability-conscious consumers. It also reduces the amount of bycatch that occurs.
There are more responsible fishing practices than bottom trawling that would allow for a sustainable relationship with the ocean.
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