Overfishing Is Erasing "Blue Carbon"! Taiwan Among the World's Top 10 Harmful Fisheries Subsidy Nations

the Editor says: The ocean absorbs approximately 2.5 billion tonnes of carbon every year, and whales along with other large fish are powerful carbon-storage champions! In the face of the global warming crisis, efforts to cut emissions are underway across every sector — yet rampant overfishing is causing "blue carbon" to vanish at an alarming rate. Confronting the thorny realities of today's fishing industry, the United Nations Conference on Trade and Development has gone so far as to state that "fisheries subsidies directly cause overfishing." Rather than simply doling out subsidies, establishing management measures, supporting fishers through the transition, and thinking through systemic solutions may be the only path to a future where fisheries and marine conservation can sustainably coexist. <Full article reprinted from the Low Carbon Life Blog, co-produced with the Environmental Information Center; author: Cao Ke-Zhi.>

Global overfishing has pushed nearly 90% of fish species to the brink of survival. Beyond the effects on ecosystems and our dinner tables, oceanic "blue carbon" is also diminishing as the carcasses of large fish disappear from the sea. Recent research has uncovered a direct link between overfishing and the loss of blue carbon. On the high seas, Taiwan's fishing fleet extracts an amount of blue carbon equivalent to the third-largest consuming nation in the world — underpinned by the seventh-highest harmful fisheries subsidy spending on the planet.

How Do the Carcasses of Large Fish Become Key Players in Carbon Sequestration?

The ocean serves as one of nature's most important carbon sinks, absorbing roughly 2.5 billion tonnes of carbon each year — equivalent to 22% of all carbon emitted by human activity. The carbon sequestration potential of coastal vegetation is equally staggering: mangroves, salt marshes, and seagrass beds together store more than 55 billion tonnes of carbon dioxide, accounting for over 50% of the ocean's total carbon storage capacity. Large marine animals such as whales also capture considerable amounts of carbon over their lifetimes — far exceeding the sequestration of many land-based plants.

A 2019 report by the International Monetary Fund (IMF) noted that each large whale stores an average of 33 tonnes of carbon dioxide over its lifetime, compared to a single tree's absorption of roughly 48 pounds (approximately 22 kg) per year. When a whale reaches the end of its long life and sinks to the ocean floor, the carbon locked in its carcass can remain sequestered in the deep sea for hundreds of years without escaping into the atmosphere.

The phytoplankton nourished by decomposing whale carcasses are themselves remarkable carbon capturers. Globally, phytoplankton supply 50% of the world's oxygen each year while capturing 37 billion tonnes of carbon dioxide — equivalent to the sequestration capacity of four Amazon rainforests. Because whale feces contain iron, nitrogen, and other nutrients that phytoplankton need, the movement of whales both horizontally and vertically through the ocean greatly promotes phytoplankton growth.

Sadly, by the 20th century the global whale population had fallen to less than 25% of pre-industrial whaling levels (from roughly 4–5 million individuals to approximately 1.3 million), with the largest species — the blue whale — reduced to less than 3% of its former numbers.

How Does Overfishing Reduce "Blue Carbon"?

The sharp decline in whales and other large fish is not only a consequence of overfishing — it also means that humans are hauling vast quantities of "blue carbon" out of the sea every year, making the fishing industry an invisible driver of global warming.

A landmark 2020 study found that enormous numbers of large fish capable of storing blue carbon are removed from the ocean through fishing every year, while the industry itself — from catch and processing through to consumption — releases ever more carbon dioxide in the process. The study, "Let more big fish sink: Fisheries prevent blue carbon sequestration—half in unprofitable areas," examined large species over 30 cm in length, including sailfish, tuna, sharks, and mackerel, and found that these fish collectively store up to 700 million tonnes of carbon per year — a truly staggering contribution.

The research revealed that between 1950 and 2014, the blue carbon equivalent of all large fish caught by global fishing vessels amounted to approximately 37.5 million tonnes over the fishes' lifetimes, of which around 21.8 million tonnes consisted of carbon that could have sunk to the deep sea. In addition, because fishing vessels run on fossil fuels, every tonne of catch produces approximately 1.9 tonnes of carbon dioxide. It is estimated that between 1950 and 2014, fishing vessels themselves emitted 165 million tonnes of carbon. Combined, the fisheries sector's total carbon output over this period reached 200 million tonnes. In 2014 alone, emissions reached 20.4 million tonnes — equivalent to the annual output of 4.5 million cars.

Looking at high-seas fishing zones specifically, 71.1% of all blue carbon extracted globally came from the Pacific Ocean, with 49.1% originating from equatorial waters within 10 degrees north and south of the equator. By country, the top three consumers of blue carbon from fishing fleets were Japan (22.2%), Indonesia (6%), and Taiwan (5.1%). Together with the Philippines, Spain, the United States, Ecuador, China, South Korea, and Thailand, these ten nations have accounted for 62% of total global blue carbon brought ashore since 1950.

The Culprit Behind Overfishing Identified: Taiwan Ranks Seventh Globally in Harmful Fisheries Subsidies

If these catches were generating enormous economic benefits for humanity, there might at least be some logic to the situation.

But the research also found that nearly half of all high-seas fishing activities would be unprofitable without subsidies. The study found that 43.5% of deep-sea fishing operations extracting blue carbon on the high seas would not be economically viable without government subsidies covering fishing port construction, vessel building, and fuel costs. The high-seas fishing grounds that could not turn a profit without subsidies saw the heaviest blue carbon depletion in waters between 10 degrees north and 20 degrees south latitude — including areas near the Japanese coast, the central Pacific, the southern Atlantic, and the northern Indian Ocean. When government subsidies are factored in, the share of "unprofitable" fishing zones drops to 23.1%.

As far back as 2022, the United Nations Conference on Trade and Development (UNCTAD) warned that "US$20 billion (approximately NT$621.4 billion) in annual fisheries subsidies are directly causing overfishing."

According to a 2021 report by Oceana, a US-based nonprofit marine conservation organization, the world's top ten "harmful fisheries subsidy" nations collectively spent US$15.4 billion (approximately NT$476.9 billion) per year in 2018, of which more than US$5.3 billion was used to subsidize their fleets to fish in foreign waters. The top three were China, Japan, and South Korea. Remarkably, Taiwan ranked seventh on the list, spending approximately NT$700 million per year on harmful fisheries subsidies.

On May 8 of this year, UNCTAD also publicly called at the third UN Trade Forum for the global community to urgently adopt a "Blue Deal" to protect precious ocean resources. The proposal seeks to ban illegal, unreported, and unregulated fishing, and to end government subsidies for high-seas fishing activities. However, the "Blue Deal" must be approved by two-thirds of the 164 member states of the World Trade Organization before it can take effect.

References

• Science Advances (October 28, 2020): Let more big fish sink: Fisheries prevent blue carbon sequestration—half in unprofitable areas
• 食力 (April 21, 2022): 每年漁業補撈3兆條魚 為陸地飼養動物的50倍！「補貼」為什麼成為過度捕撈元兇？
• IMF (December 2019): Nature's Solution to Climate Change
• OCEANA (June 2021): Tracking Harmful Fisheries Subsidies
• 環境資訊中心 (October 2, 2019): 一條鯨魚抵幾千棵樹 緩解暖化天然神器 「護鯨就是固碳」
• 環境資訊中心 (January 21, 2022): 海洋「藍碳」會是未來碳儲存的潛力股嗎？
• UNCTAD (May 8, 2023): Global 'Blue Deal' urgently needed to protect and invest in our ocean

Further reading:

• 極度瀕危 研究揭北大西洋露脊鯨暖化困境 北移覓食反陷另一危機
• 纏繞成鯨魚第二大死因 美國研發「無繩」捕龍蝦漁具
• 海洋3法率先通過三讀的海洋產業發展條例
• 鯖魚、竹莢魚縮水，白鯧僅 6 公分！憂生態失衡，環團催海洋保育法加速通過

Reprinted with permission from the Environmental Information Center and the Low Carbon Life Blog. Original title: Overfishing Is Erasing "Blue Carbon"! Taiwan Among the World's Top 10 Harmful Fisheries Subsidy Nations