How overfishing is threatening the world’s oceans and why it could end in disaster
Scientists have long been sounding the alarm about a looming catastrophe of ocean overfishing – the removal of wildlife from the sea at rates too high for species to replace. Yet for two decades, world leaders have been at an impasse in their efforts to undo the damage that has been done.
Marine scientists know when widespread overfishing of the seas began. And they have a pretty good idea of when, if nothing is done, it will end badly. Here’s a look at the critical issues of overfishing, from its effects on biodiversity to the limited successes of mitigation efforts.
Why Overfishing Happens
The first overfishing occurred in the early 1800s when humans, in search of grease for lamp oil, decimated the whale population around Stellwegen Bank off Cape Cod. Some fish eaten in the United States, including Atlantic cod, herring, and California sardines, were also caught on the brink of extinction in the mid-1900s. These isolated, regional depletions severely disrupted the food web, which n t has become more precarious than at the end of the 20th century.
In the mid-20th century, countries around the world struggled to build their fishing capacity to ensure the availability and affordability of protein-rich foods. Favorable policies, loans and subsidies spawned a rapid rise in large industrial fishing operations, which quickly supplanted local fishermen as the world’s main source of seafood.
These large, profit-seeking commercial fleets were aggressive, scouring the world’s oceans and developing ever more sophisticated methods and technologies to find, extract and process their target species. Consumers have quickly become accustomed to having access to a wide selection of fish at affordable prices.
But by 1989, when around 90 million tonnes (metric tons) of fish were taken from the ocean, the industry had peaked and yields have declined or stagnated ever since. Fishing for the most sought-after species, such as orange roughy, Chilean seabass and bluefin tuna, has collapsed for lack of fish. In 2003, a scientific report estimated that industrial fishing had reduced the number of large ocean fish to just 10% of their pre-industrial population.
How overfishing affects biodiversity
Faced with collapsing populations of large fish, commercial fleets began to travel deeper into the ocean and further up the food chain for viable catches. This so-called “fishing down” has set off a chain reaction that is upsetting the ancient and delicate balance of the sea’s biological system.
Coral reefs, for example, are particularly vulnerable to overfishing. Herbivorous fish maintain the balance of these ecosystems by eating algae, keeping the coral clean and healthy so it can thrive. Catching too many herbivores, whether intentionally or through bycatch, can weaken reefs and make them more susceptible to damage from extreme weather and climate change. Fishing gear and debris can also physically destroy the fragile corals that form the foundations of reefs.
Overfishing can also harm other marine species. Trawling, a method in which boats drag huge nets behind them through the water, attracts more than shrimp and bluefin tuna – it catches just about anything in its path. Sea turtles, dolphins, seabirds, sharks and other animals have all faced existential threats as bycatch.
Efforts to prevent overfishing
Over the years, as fisheries have fished less and less, humans have begun to realize that the oceans, supposedly endlessly vast and rich, are actually very vulnerable. In 2006, a study of catch data published in the journal Science have grimly predicted that if such unsustainable fishing rates continue, all of the world’s fisheries will collapse by 2048.
Many scientists say most fish populations could be restored through aggressive fisheries management and better enforcement of harvest laws, including instituting catch limits. Increased use of aquaculture, seafood farming, would also help. And in many areas, there are reasons for hope.
The Food and Agriculture Organization of the United Nations (FAO) – which sets international standards for fisheries management – highlighted in its 2020 report that there has been a slight increase in the percentage of stocks that produce sustainably as much food as possible, which is the goal of fisheries management.
Yet many challenges remain. About a third of the world’s stocks are overexploited and the global proportion of fish stocks at sustainable levels has continued to decline. The FAO report says that this deterioration of fish stocks is particularly visible “in places where fisheries management is not in place or is ineffective”. Of the areas monitored by the organization, the Mediterranean and Black Sea had the highest percentage of stocks – 62.5% – fished at unsustainable levels.
Can we stop overfishing?
Government subsidies to the fishing industry remain a significant challenge to reversing this worrying trend. A global survey found that in 2018 countries spent £16billion on so-called harmful subsidies that fuel overfishing, a 6% increase on 2009.
Like National geographic reported at the time, harmful subsidies are those that fund practices that would otherwise be unprofitable, such as the fuel costs of industrial trawlers. China, for example, has increased its harmful subsidies by 105% over the past decade.
Members of the World Trade Organization have been discussing how to limit these subsidies since 2001, with little progress. And despite the promise of UN members to strike a deal by 2020, that deadline has passed without a resolution.
In 2021, WTO Director-General Ngozi Okonjo-Iweala called on members to reach an agreement, arguing that “failure to do so would jeopardize ocean biodiversity and the sustainability of fish stocks whose so many people depend on them for food and a living.”
It is unclear whether countries will muster the political will to follow. But what is clear to scientists is that it is one of many essential measures to save the world’s oceans.