Commercial Fishing: How Global Food Choices Negatively Impact the Oceans

commericial fishing boat

The world’s commercial fishing industry often operates unsustainably in order to meet the growing demand for seafood. Modern technological developments have birthed huge ships equipped with fishing gear that can stretch for miles through the water, creating an industry akin to that of industrial animal agriculture on land. With an eye towards profits, this industry often overlooks sustainability and the welfare of marine animals. The following is a look into the commercial fishing industry and its impacts.

What Is Commercial Fishing?

Commercial fishing is done for profit, converting marine life into human food, fish meal for aquaculture, and other products. Commercial fishing is distinct from subsistence fishing, which is small-scale fishing done by a person in order to directly feed themselves, their family, and their community. Commercial fishing feeds the masses and provides resources for markets around the world, and is increasingly effective at turning a profit: one analysis valued the global market for commercial fishing at around $240.99 billion in 2017, and anticipates growth by 2026 to $438.59 billion.

Commercial fishing can range from being relatively small-scale, involving smaller ships plying a limited ocean area, to industrial fishing, which involves large vessels, even larger nets, and the capacity to process and store vast quantities of fish. Similar to industrial animal agriculture’s signature factory farms, industrial fishing deploys factory ships, also called supertrawlers, which can remain out at sea for weeks and months at a time. These ships, which can be over 100 feet in length, can catch hundreds of tons of fish every single day, without pausing to bring their catch ashore for processing or freezing since these things are done on the ship itself. The industry’s efficiency at catching and killing fish makes it a significant factor contributing to the global decline of sustainable fisheries.

Commercial fishing generally does not take into account the ability of fish to experience pain or emotional states such as depression. Unlike animals on factory farms, where welfare indices (however inadequate) are used to measure pain and stress in individuals, marine animals are generally afforded none of these considerations. Fish can often endure prolonged deaths by air asphyxiation, a process that can take over an hour for some species. For those who are gutted alive, certain species can remain living for over an hour.

Types Of Commercial Fishing

The commercial fishing industry innovates in order to catch the most fish with as few resources expended as possible. The bigger the nets or the longer the lines, the more marine life can be brought out of the depths at one time, reducing the amount of time and fuel a ship needs to spend on the water.

Fishing With Nets

Out of all the commercial fishing methods, it is likely fishing nets that wind up taking the most lives. Between purse seines, trawls and gillnets, an enormous volume of sea life can be gathered up and processed with great efficiency. 

Purse Seine

Purse seine nets are used in open water to catch species such as tuna. A wall of netting is laid around a school. The top floats upon the surface, while the bottom hangs down, forming a large cylinder. The bottom is then drawn together, trapping the fish as from escape. This drawstring effect is where these nets get their name, from purse drawstrings.

Purse seine nets are controversial especially when it comes to bycatch. In the eastern tropical pacific ocean, dolphins and tuna tend to swim together for reasons that are still unknown. Because dolphins are air-breathers, they must constantly break the surface of the ocean and inadvertently give away the position of tuna beneath them. Commercial fishing vessels have been known to target pods of dolphins, assuming there will be tuna beneath them. Both tuna and dolphins are encircled in the purse seine net, and although at times efforts can be taken to let the dolphins out of the nets before they are drawn aboard, many wind up drowning in the process.


Trawling involves dragging a net behind a ship, collecting fish along the way. There are two types of trawling: pelagic and bottom trawling. During pelagic trawls, the net is pulled through the open water, without making any contact with the bottom. Also known as midwater trawling, the species targeted include tuna, shrimp and anchovies. A pelagic trawl net can be 650 feet wide and nearly 500 feet long. To put this into perspective, the Seattle Space Needle is 500 feet tall. Pair pelagic trawling, on the other hand, involves two vessels, each holding one side each of a truly massive midwater trawl net. Some of the biggest nets are a mile long, and large enough to easily contain ten jumbo jet planes. Pelagic trawling has negative impacts on dolphins and whales, since these nets are large enough to scoop up entire pods. It’s estimated that 300,000 cetaceans are killed as bycatch around the world each year, which is the reason places such as England have banned pair trawling from territorial waters. 

Bottom trawling nets are weighted down so they can be dragged across the ocean floor. Known as the ocean’s bulldozers, these nets can destroy ocean-bottom environments with a single pass. Many species of deep-sea corals are slow-growing and can live for hundreds of years. Bottom trawling cuts down these corals and decimates the surrounding habitat, with an effect similar to that of clear-cutting great swaths of forest. Bottom trawling nets can be three stories tall and as wide across as a football field.


As their name suggests, gillnets are designed to capture fish by their gills – the respiratory organ on either side of a fish’s face. Their design allows a fish to push only their head through the netting, but not the rest of the body. The mesh of the netting allows for certain species to be targeted, which can include tuna, swordfish, and salmon. Beyond mesh size, there are two primary kinds of gillnets: those that are set into an anchor system that keeps the net in place in the water column and drift gillnets that are attached to buoys and weighted to keep them beneath the surface.

As with other types of net fishing, gillnets result in vast amounts of bycatch. Animals such as turtles, dolphins, and seabirds become entangled in gillnets and drown, their bodies discarded back into the oceans after being collected and disentangled.

Fishing With Line

Many people are acquainted with fishing rods available in sporting goods stores – the sort used for weekend trips to the lake. With a rod and reel, fishing happens one at a time, as opposed to nets that can catch a whole school at a time. Commercial line fishing tends to be lower-volume, however, the industry has found ways to maximize the amount of fish pulled from the waters using hook and line. Below are two common commercial line fishing methods used today.


Longlines are a series of baited hooks attached to one mainline, which can run fifty miles long. Hanging suspended in the water column, longlines are used to catch species like swordfish and mahi-mahi. Unintentional bycatch of sharks, turtles, and seabirds are common.

Pole And Line

Pole and line is a commercial fishing technique used for species like tuna. The process begins with baitfish such as sardines, who are usually alive. These fish are tossed into the water or are impaled onto barbless hooks. The fishing vessel sprays a fine mist over the surface of the water to obscure the activity on the deck from the fish.  When a target fish becomes hooked, the fisherman flings the fish up out of the water and onto the decks behind, and because the hook is barbless the fish slips off, allowing the fisherman to immediately put the hook back into the water with one fluid motion. Sometimes fish are gaffed –  stabbed in the sides of their bodies with a long hook attached to a pole –  in order to bring them on board.

Pole and line fishing is often touted as being a sustainable alternative to methods such as purse seine fishing, particularly when it comes to tuna. However, this fishing method has been shown to produce a significant amount of greenhouse gas emissions, since boats must travel further in their quest for fish. 

Harvesting Shellfish

Shellfish can be harvested for food or materials (such as oysters for their pearls). Species of shellfish common for harvesting include clams, mussels, crabs, lobsters, shrimp, scallops, and crayfish. The following are two common shellfish harvesting methods.


Dredging for species such as clams involves dragging heavy metal baskets across the ocean floor. Similar in technique to bottom trawling, dredging baskets are equipped with metal teeth that dig into the seafloor, forcing shellfish upwards into the water which are then collected into the baskets. Dredging creates plumes of sediment which can muddy water and negative impacts for underwater habitats.

Traps And Pots

Traps and pots are essentially cages designed to lure, and ultimately trap, bottom-dwelling species such as crabs and lobsters. Made out of metal or wood, these traps are baited and left on the bottom of the ocean floor. Their design allows target species to enter the device but prevents their escape. 

Traps and pots are attached to one another by a rope, which leads to a buoy that floats on the surface, allowing fishermen to easily spot traps for retrieval. These ropes pose serious threats to marine life including the highly endangered Atlantic right whales and other species, who can become entangled and drown. 

Is Commercial Fishing Dangerous?

Commercial fishing is designed to be dangerous to targeted species and is unintentionally dangerous for species who are bycatch, and for the world as the ecological balance of the oceans is upset. The arsenal of sophisticated equipment, enormous nets, radar, and floating abattoirs make it seem as though the commercial fishing industry is waging war on the oceans – and unfortunately, it is a war humans are winning.

What Are The Impacts Of Commercial Fishing?

The neoliberal underpinnings of commercial fishing industries have, in many ways, resulted in a tragedy of the commons: because the surface area of the world’s oceans is so vast, any regulation ensuring that no single enterprise is taking more than their fair share is notoriously difficult to achieve.  Within both coastal fisheries and the high seas, those vast lawless areas which belong to no one and everyone, a free-for-all has been taking place for decades. Illegal, unreported, and unregulated fishing practices mean that supertrawlers and other commercial vessels can scoop up vast amounts of marine life while facing little to no regulation or limitations on how much they can take, or abide by sustainability mandates.  Supertrawlers are also regularly seen illegally fishing within protected areas.

Aside from deliberately catching vast numbers of fish and engaging in practices like trawling which cause damage to ocean habitats, commercial fishing accounts for vast quantities of bycatch – where non-target species of marine animals are accidentally (or sometimes intentionally) caught, then tossed dead or dying back into the oceans. By some accounting, bycatch accounts for around 40 percent of the total global catch – amounting to 63 billion pounds of needlessly killed animals. And while those numbers aren’t exclusive to large-scale commercial fishing, it’s safe to assume that the industry accounts for a significant percentage of this by virtue of commercial vessels’ enormous catching and processing capacities. 

Where Does Most Commercial Fishing Take Place?

Commercial fishing takes place in virtually every corner of the oceans. Different species of marine animals congregate in different areas, however, the planet’s coastlines tend to be fertile fishing grounds. One United Nations report found the Northeast Atlantic, Northwest Pacific, Southeast Pacific, and Western Central Pacific to have yielded the most catch. 

Importance of the Oceans

While we call this planet Earth, the reality is that land only accounts for about 30 percent of the earth’s surface, with oceans covering the rest. Perhaps a better name for Planet Earth would be Planet Ocean. Besides providing a home for countless species of marine life and serving as a significant source of protein for many countries, the oceans play critical roles in maintaining stability within the earth’s dynamic systems. Oceans generate over half of the planet’s oxygen and are vast carbon sinks – meaning they absorb carbon dioxide out of the atmosphere. Their role in regulating the world’s weather makes oceans of critical importance as well. Huge underwater currents help disperse heat from warm areas into cool ones, causing seasonal weather patterns that humans and other species rely upon.

How You Can Help

One of the most effective ways to prevent the negative environmental impacts of commercial fishing is to remove seafood from your diet. If you do choose to eat seafood, follow consumer guides to purchase fish that are caught sustainably (although it is increasingly difficult to call any seafood harvesting “sustainable”).

You can also support the creation of Marine Protected Areas, which can prohibit commercial fishing vessels from entering protected waters. Under 2% of the oceans are currently completely protected from fishing or other extractive activities, within areas referred to as “no-take MPAs”. Yet when areas are allowed to recover from exploitation, the improvements are often seen swiftly, making a larger network of no-take MPAs a powerful potential solution. 


Commercial fishing represents an environmental threat to many species of fish throughout the world’s oceans, particularly with increasingly efficient technology including factory ships and nets that can extend for miles. Given the importance of the oceans in regulating much of the world’s food supply to the weather itself, hopefully, commercial fleets can improve their sustainable practices and respect the oceans and life therein.