According to a controversial study, the controversial bottom trawling is at least as damaging to the climate as global air traffic. Churning up the ground with heavy fishing gear releases an average of one gigatonne of CO₂ every year, according to the authors of the study, which was published in the journal Nature. For comparison: Before Corona, aviation was responsible for the annual emission of around 900 million tons of CO₂.
The fishing gear releases organic carbon compounds from the agitated sediment layer on the sea floor and converts them into climate-damaging carbon dioxide. As a result, the oceans acidify more quickly, and the seas can then absorb less CO₂ from the air. This in turn increases the greenhouse effect because the oceans are the largest CO₂ reservoir on earth. The fishing methods also threaten the biological diversity of the seas, write the total of 26 marine biologists, climate experts and economists in the study.
Bottom trawling is a globally widespread method of catching marine animals such as plaice, sole and shrimp. In order to collect crustaceans from the seabed, for example, the fishermen hit the ground with heavy dishes and small-meshed nets. The method has many critics because its use destroys the sea floor and many creatures living on it are destroyed. Researchers warn that spawning grounds are being churned up by fish and plants being uprooted. This silts up and silts up the sea floor.
Bottom trawls usually consist of a funnel-shaped collection bag that is pulled by one or more ships. The mouth-like opening of the net is created using weights below and floating bodies above. Otter boards pull the net apart and can create furrows in the ground, kicking up sediment.
Protected areas also benefit fishermen
In order to better protect the seas, the study authors advocate more protection zones in which trawling is prohibited. Such Marine Protected Areas (MPA) already exist. However, according to the International Union for Conservation of Nature (IUCN), which manages the protected areas for the UN, there are no uniform regulations. It therefore always depends on the judgment of the neighboring countries whether fishing is allowed in the zones or tourism is allowed.
According to the “Nature” study, just under three percent of the world’s oceans currently have a high protection status. Only seven percent are more or less strictly designated as a protected area. According to the researchers, this proportion should increase by at least 30 percent, but better by up to 45 percent – depending on how much biodiversity and fish wealth the world community wants to preserve.
The scientists are not only interested in environmental protection. Fisheries could also benefit from the recovery of the seabed. The protection of “strategic” marine areas can produce up to eight million tons of additional seafood, it is said.
The study is another topic for the biodiversity summit this year. As it became known on Friday, the parties to the UN Convention on Biological Diversity want to meet in the southern Chinese city of Kunming in October to adopt a roadmap for the protection of biological diversity. The meeting has already been postponed several times due to the corona pandemic. An agreement is to be drawn up there with a similar scope to the 2015 Paris Climate Agreement.