Seaspiracy explored: Why is bottom trawling and bycatch such bad news?
‘Seaspiracy’, the popular Netflix Documentary released earlier this year, has made words like “bycatch” and “overfishing” everyday language. Previously in technical terms, the film catapulted these destructive fishing industry practices into the mainstream.
The film shed light on an industry that has long escaped scrutiny and the impacts of which we are already seeing. We have heard from many readers who quit eating fish after watching the movie.
But the film has been criticized for the onslaught of facts and statistics it throws at viewers. Some struggled to really take in all the information presented to them.
So here we are going to dive deeply, by play on words, into what bottom trawling and bycatch, two axes of “Seaspiracy”, really mean for our oceans.
What is bottom trawling?
Bottom trawl is an industrial fishing method where a huge net with heavy weights is dragged along the seabed, picking up everything in its path.
Huge is an understatement. As ‘Seaspiracy’ puts it, “the biggest trawls are so big they can swallow entire cathedrals or up to thirteen jumbo jets.”
How does bottom trawling contribute to global warming?
This year saw the publication of the first study ever to calculate the carbon cost of bottom trawling. “Protecting the Global Ocean for Biodiversity, Food and Climate” revealed that bottom trawling releases as much CO2 as the aviation industry as a whole.
It is imperative to keep carbon where it is stored, rather than releasing it into the atmosphere where it increases global temperatures.
As Dr. Trisha Atwood, co-author of the report, says, “The ocean floor is the largest store of carbon in the world. If we are to succeed in stopping global warming, we must leave the carbon-rich seabed intact.
“Yet, every day, we trawl the seabed, depleting its biodiversity and mobilizing millennial carbon and thus exacerbating climate change. “
The study, produced by a team led by Dr Enric Sala of the National Geographical Society, found that bottom trawling produces 1 gigatonne of carbon each year.
So what’s the deal with increasing carbon in the oceans? It increases acidification, reduces biodiversity, and damages the ocean’s ability to absorb carbon, thereby damaging its ability to act as a crucial reservoir in the future.
What can be done to stop bottom trawling?
The good news is that governments have the power to put an end to the harmful effects of bottom trawling. Countries with large national waters where bottom trawling takes place could eliminate 90% of the risk of carbon disturbance by protecting only 4% of their waters.
“In this study, we have developed a new way to identify places which, if strongly protected, will stimulate food production and preserve marine life, while reducing carbon emissions,” says Dr Sala. .
“Humanity and the economy will benefit from a healthier ocean and we can realize these benefits quickly if countries work together to protect at least 30% of the ocean by 2030.”
Key areas for marine protection
Using an algorithm, the researchers identified that if at least 30% of the ocean was protected, biodiversity would improve, marine life would return, and climate benefits would follow.
They found that priority areas for protection included:
- Dogger Bank in the North Sea
- Mid-Atlantic Ridge
- Mascarene Plateau in the Indian Ocean
- Nazca Ridge on the west coast of South America
- Southwest Indian Ridge, between Africa and Antarctica.
Charles Clover, executive director of the Blue Marine Foundation, says studies like this are vital.
“The science is clear – destructive fishing is the greatest threat to marine life – and is massively accelerating climate change,” he says.
“The interests of European citizens lie primarily in the protection of biodiversity and the fight against climate change – and not in the protection of vested interests in the fishing industry. It is time to put in place measures to protect seabed habitats from the Arctic Circle to the Mediterranean. “
Bycatch follows bottom trawling
Bycatch are all marine species accidentally caught in trawler nets, alongside target fish. This happens because the nets are so huge and weighted down that marine life has no choice but to be dragged into the net. Most of the species caught in the nets are rejected and thrown overboard, dead.
The extent of damage to the Dogger Bank from bottom trawling and industrial fishing has been analyzed by Blue Marine Foundation, Client Earth, Marine Conservation Society and WWF. They found that the area, 100 km from the east coast of England, was so badly damaged that it should be a “test case” for the conservation of European marine protected areas.
As a region, it stores the greatest amount of blue carbon in UK waters. It holds around 5.1 million tonnes in the seabed, which equates to 31,000 round-trip flights from London to Sydney.
The UK, the Netherlands and Germany undertook a separate study on the Dogger Bank, which showed that bottom trawling resulted in a marine environment dominated by short-lived invertebrates rather than species endangered species such as skate and Atlantic halibut.
The three countries plan to declare 18,765 square kilometers of Dogger Bank a marine protected area, with the UK already planning to introduce a regulation covering its section in the near future.
“The worst enemy of a successful fishery is overfishing – not protected areas”
“Some argue that closing areas to fishing harms fishing interests. But the worst enemy of a successful fishery is overfishing, not protected areas, ”says Dr Sala.
Evidence from existing marine protected areas shows that protect an area increases fish stocks in surrounding waters. For example, warming waters and reduced oxygen caused a major decline in abalone at Dogger Bank in 2010. But the survival of highly reproductive abalone in a nearby protected area has resulted in the rebuilding of stocks of abalone. fish throughout the region.
In addition, capture densities have increased by up to 90% in five years. The closure of the areas around the Isle of Arran, Isle of Man, Lundy and Skomer to dredging has also resulted in a significant increase in the number of scallops and lobsters.
Taking action to ban bottom trawling in specific areas like Dogger Bank would also protect over 80% of the habitats of endangered marine species, while ultimately creating the potential to increase fishing catches by over 8 million. metric tons.
Better yet, it would protect current and future carbon storage, helping us to avoid total climate degradation.