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Bottom Trawling: What’s the Catch?

December 23, 2021

As the demand for fish continues to rise, marine ecosystems and fisheries around the world are collapsing. In order to keep up with the high demand, fisheries have persistently employed unsustainable tactics to catch fish, including the use of bottom trawling. Such tactics have caused a global domino effect which is negatively impacting vital fish populations, the economy, and consumers. According to research done by the Marine Conservation Institute, “90% of global fish populations are fully-fished or overfished.” Let’s dive into why bottom trawling is a leading contributor to that statistic.  

Trawling nets are designed to capture tremendous amounts of fish by dragging large weighted nets across the sea floor. A standard net contains a wide mouth while the end of the net is more confined. This fishing method eradicates all benthic communities, as well as large sea animals, in its path as they are devoured by the nets. The victims include sea turtles, schools of fish, sharks, and even coral reefs. Studies have found that “many species are being fished to the brink simply as a consequence of commercial activities, not as the target of them.” Also referred to as bycatch, these animals are discarded back into the ocean, leaving them exposed in open waters and threatening the biodiversity of the ocean. In fact, roughly “437 million tons of non-target fish and invertebrates” have unintentionally been caught by trawling nets and thrown back into the ocean. To put that into perspective, researchers from Oceana “estimate that 17 to 22 percent of U.S. catch is discarded every year,” which could amount to two billion pounds. Bottom trawling fits into this because nearly 50 percent of all bycatch is a result from trawling fisheries. This large-scale loss on our marine ecosystems not only reduces productivity but also leaves them “vulnerable to invasive species, disease outbreaks, and noxious algal blooms,” according to professor of biological sciences at Stanford, Stephen Palumbi. 

In addition to bycatch, a direct effect of bottom trawling is its detrimental impact on small-scale and large-scale fishermen. Since bottom trawling has led to a decline in fish populations, this means there are fewer viable jobs for fishermen. To demonstrate the severity of this, the UN Food and Agriculture Organization (FAO) estimated that “77 percent of the world’s fish stocks are exploited at or beyond their maximum sustainable levels.” This statistic is alarming to small-scale fishermen who must compete with bottom trawl fisheries. With fewer resources and fish in the water, they are yielding fewer fish. 

To worsen the situation, the fishing industry has developed trawling nets to enable them to cover complex seabed habitats with little resistance. These modifications include rockhoppers and “canyon busters.” With this advanced technology, coral is being depleted at alarming rates. On the South Tasman Rise, for example, “fisheries targeting orange roughy caught an estimated 1.6 tons of coral for each hour of towing a trawl net during the first year of the fishery.” When trawls remove entire coral reef communities they are removing food, fish habitats, and tourism attractions, which hurts the economy. 

In spite of these damages, change is being made. Federal regulations are being implemented across the world to reduce the impacts of bottom fishing. This includes closing specific areas to restore stressed habitats such as in the Gulf of Mexico, New England, and Gulf of Alaska. However, one way we can all contribute to the restoration of marine ecosystems is by transitioning to a plant based diet. By eliminating the source from our meals we can decrease the demand for fish, thereby lessening the usage of bottom trawls. By recognizing the importance of preserving the world and its vast resources, we can take tremendous steps towards saving this fragile ecosystem.