In Defense of an Enormous Marine Reserve at the High Seas

Photo by Pierre Leverrier on Unsplash

When Columbus first travelled to the Americas, it is said that his men would complain that they couldn’t sleep over the racket of gigantic animals colliding with the ships hull. In the 17th century, it is estimated that more than 90 million green sea turtles roamed the oceans. Today there are no more than 300 thousand.

The seas were full of life and that shaped the mentality of fishermen and the overall society. But the ocean has lost much of it’s wildlife in the last centuries due to overexploitation. Wild capture rose dramatically from the 1950s, peaking around 1996 due to a combination of fishing regulation plus a lack of fish to catch. Since 1996, catch has declined. Currently, the total reported wild catch is around 80 million tonnes, but when estimates of unreported catch and discarded fish are included the number could be closer to 130 million tonnes.


In 1974, the share of fish stocks within biologically sustainable levels was 90%. By 2013 this had shrunk to 68%. This means that 32% of fish stocks (almost one third) are being fished at unsustainable levels. The situation is particularly critical for migratory fish that are fished solely or partially on the high seas.


Industrial ships operate globally and search for the most profitable fishing grounds, like the area off the coast of West Africa, where there is little state regulation and they can easily outcompete the locals. Industrial operations employ 25 times less than artisanal and fishes far more with more efficient yet more environmentally harmful techniques. Thus exhausting traditional fishing grounds and depriving traditional fishing communities from their livelihood.

When habitats are over exploited, the efforts to extract the remaining fish is unjustified and not compensated by the revenue. Instead, transforming that area in a reserve can be lucrative for local communities that could profit from conservation and conscious tourism, keeping the regenerated habitat alive and well.

The ocean has an immense regenerative potential. Recent experiences have shown that only few years of “no-take” marine reserves bring back the area to near pristine conditions, including top predators such as sharks, that are known to be indicators of the health of marine ecosystems.

But today, only 2% of the ocean is fully protected. Studies suggest this number needs to be at least 30%. It is fundamental to keep it healthy as to safe guard human life as well. At a global scale, the ocean is responsible for producing more than half the oxygen in the atmosphere , for slowing down climate change (absorbing carbon dioxide from the atmosphere) and providing food and livelihood for many.

Despite all that, governments have been subsidizing the fish industry disregarding the conditions to what workers are subjected to and the amount of ecological damage they cause. In countries like Portugal and Spain, the fear of unemployment, drove these governments to increase subsidies (or “incentives”) on low profitable fisheries. Indirect subsidies, such as those on oil prices also contribute to keep fish prices low and incentivise over exploitation in low productive regions.

The High Seas

Coastal countries have authority for 200 miles from shore, inside their Exclusive Economic Zones (EEZ). Waters beyond that, are inside what is called The High Seas , otherwise known as “International Waters”. There is no country ownership there. But that doesn’t mean it belongs to no one. Instead, it belongs to everyone, thus there should be a shared responsibility. In fact, The Convention on the High Seas signed in 1958 codifies the laws regarding international waters.

The High Seas are higlighted in dark blue and EEZs in light blue. Source

Fishing in the high seas is allowed. But in a typical tragedy of the commons, it is seen as a free for all area, and is overexploited. Fishing there occurs in two main ways. Either by bottom trawling, which is super destructive (some trawlers have nets that could fit twelve Boeing 747 and catch everything, including corals) and surface fishing, that targets specific species such as tuna and sharks but that are usually already under threat of population decrease.

Until now, we knew little about the state of high seas fishing. It is difficult to monitor vessels and track their origin, as well as the origin of the fish caught and sold. Companies and countries did not collaborate, since they benefit from this lack of transparency.

In order to make data available and better understand how those fisheries operate, Global Fishing Watch have been able to track boats using automated identification systems based on satellite images and machine learning algorithms. Their results, published in an article in Science Magazine showed that China, Taiwan, Japan, Korea, Indonesia and Spain account for roughly 80% of high seas fishing.

Besides, they were able to monitor the whole extent of the ocean and indicate where fishing is more intensive and where it is more profitable. In the image below, we can see that most of the high seas fishing is profitable when subsidies are applied and little or no worker’s rights are observed. When there are no subsidies and fair wages/conditions are observed, most of those profitable regions become unprofitable.

Why do countries subsidize an industry that is fundamentally based on human exploitation and environmental destruction? And that is not even so profitable after all!?

Closing the high seas to fishing would have strong environmental, economical and social benefits. It would replenish fish populations that would again populate shallow waters closer to shore, which could then be fished at significantly more profitable distances. Furthermore, fisheries operating in EEZs are more prone to respect worker’s rights and environmental laws.

Besides, it wouldn’t deeply affect our capacity to feed human populations, since only 5% of marine catch comes from the high seas and usually ends up in plates of tuna sashimi and shark’s fin soup.

In 2017, the United Nations started a two year process to make a new rulebook to regulate the high seas, the High Seas Treaty, and the issue concerning the preservation of this huge international area is high at

Greenpeace’s head of oceans Will McCallum told The Guardian:

“This is the biggest opportunity to change the status quo we have ever had. It could change everything.”

The new agreement is unlikely to protect all of the high seas. Countries seem to agree in expanding reserves from 5% to 10%, while conservationists and scientists claim this number should be at least 30%.

Even if we can’t transform all of it, a conservation proposition of this measure has never been done in our history, and scientists believe they have enough data from satellites, tagged animals and survey ships to evaluate which regions should be protected first.

As put by Science Magazine:

“…combined biological data, such as the distribution of fish, sharks, and whales, with oceanographic information, such as the locations of seamounts, trenches, and hydrothermal vents. They identified ocean currents, potential mining areas, and biologically productive zones where deep, cold waters rise to the surface. And they located places where ocean temperatures hold steady most of the year — potential safe havens from global warming — as well as areas with large temperature fluctuations, which might harbor creatures preadapted to cope with warming.”

Although this new treaty probably won’t have optimal results in protecting international waters and fish stocks, since the area may not be sufficiently large, enforcement will be complicated and fishing sustainably inside EEZs demands another big effort from industries and countries, the radical decline in populations of marine animals in the last 20 years requires a great endeavor.

Photo by Ibrahim Rifath on Unsplash

Henrique Back

Written by

Materials Engineer. Currently researching the topic of microplastic pollution. Interested in Environmental Protection and Data Analysis

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