Marine Resource Management: Ensuring the Sustainability of Ocean Assets

Oceans cover more than 70 percent of Earth’s surface, yet the way humanity manages – or mismanages – these vast waters will define ecological and economic outcomes for generations to come. Marine resources sustain food systems, drive economies, regulate the global climate, and harbour an extraordinary range of biodiversity. But they are under mounting pressure from overfishing, pollution, habitat destruction, and the accelerating effects of climate change. Effective marine resource management is no longer optional; it is one of the most urgent sustainability challenges of the 21st century.

The value of marine resources 🔗

Marine resources broadly encompass everything the ocean provides – living resources such as fish, shellfish, seaweed, and marine mammals; non-living resources such as oil, gas, and seabed minerals; and ecosystem services including climate regulation, oxygen production, and carbon absorption. According to the United Nations, the ocean covers three-quarters of Earth’s surface, contains 97 percent of Earth’s water, and represents 99 percent of the living space on the planet.

Fisheries alone are a cornerstone of global food and economic security. The FAO’s State of World Fisheries and Aquaculture 2024 reports that global marine capture fisheries produced around 79.7 million tonnes of aquatic animals in 2022, valued at approximately USD 159 billion. Aquatic animal foods supply 15 percent of animal proteins worldwide and are a critical source of omega-3 fatty acids, minerals, and vitamins for billions of people – particularly in coastal and island communities where seafood is the primary protein source.

Beyond fisheries, the ocean floor harbours vast mineral wealth. Polymetallic nodules, hydrothermal vents, and deep-sea sediments contain manganese, cobalt, nickel, copper, and rare earth elements that are increasingly targeted for extraction. FAO research on deep-sea resources estimates the economic value of deep-sea ecosystem services at USD 267 billion per year, with 92 percent of that value originating from abiotic resources such as oil and minerals. In addition, the ocean absorbs roughly 23 percent of annual CO₂ emissions from human activity and has absorbed more than 90 percent of the excess heat in the climate system – services that are impossible to price adequately but are foundational to planetary stability.

Threats to marine ecosystems 🔗

Despite this enormous value, marine ecosystems face converging and intensifying pressures that are eroding their health and productivity at an alarming pace.

Overfishing and illegal fishing 🔗

Overfishing is among the most acute threats. According to the FAO, the fraction of marine fish stocks fished within biologically sustainable levels dropped to 62.3 percent in 2021 – down from 90 percent in 1974. Put differently, nearly 37.7 percent of global stocks are now being fished at biologically unsustainable levels. The economic cost is staggering: poor fisheries management results in foregone revenues of more than USD 83 billion annually. Regional hotspots are particularly severe – in the Southeast Pacific, 66.7 percent of fish stocks are at unsustainable levels, and the Mediterranean Sea and Black Sea follow closely at 63.3 percent. Illegal, unreported, and unregulated (IUU) fishing compounds the problem further by undermining science-based quota systems and depleting stocks beyond what official data captures.

Marine pollution 🔗

Pollution enters the ocean from multiple land-based and maritime sources – agricultural runoff carrying excess nutrients, industrial discharges, shipping waste, and the steadily rising tide of plastic debris. UN SDG indicators data estimates that more than 17 million metric tons of plastic entered the world’s ocean in 2021 alone, making up approximately 85 percent of all marine litter – with projections suggesting this volume could double or triple by 2040. Nutrient pollution from agriculture drives coastal eutrophication, creating oxygen-depleted “dead zones” that have grown from around 400 globally in 2008 to approximately 700 by 2019. Simultaneously, UNESCO’s 2024 Ocean Report warns that ocean acidity has risen by 30 percent since the industrial era and could increase by 170 percent by 2100 if emissions are not curtailed – a change that compromises the ability of shellfish, corals, and juvenile marine organisms to form their shells and skeletons.

Habitat destruction and climate change 🔗

Coral reefs, seagrass beds, mangroves, and kelp forests are among the most productive and biodiverse marine habitats – and all are under threat. Between 2009 and 2018, the world lost about 14 percent of its coral reefs. Ocean temperatures have risen at an accelerated rate over the past two decades, doubling in speed compared to the preceding period, triggering widespread marine heatwaves that bleach coral reefs and disrupt migratory patterns. Coastal development, bottom trawling, and destructive fishing practices physically degrade habitats that serve as nurseries for commercially important fish species, and the combined effect of these pressures is a measurable global decline in marine biodiversity. Research published in PMC confirms that marine biodiversity is declining globally at an alarming rate, driven by multiple interacting human pressures that degrade ecosystem function and shift species distributions in ways that are not fully predictable.

Conservation and management strategies 🔗

Addressing these threats requires a combination of regulatory, spatial, and community-based strategies that operate at local, national, and international scales.

Marine protected areas 🔗

Marine Protected Areas (MPAs) are one of the most widely used conservation tools. They work by restricting or prohibiting extractive activities within defined ocean zones, allowing ecosystems to recover and biodiversity to stabilize. According to UNESCO’s 2024 report, 72 percent of endangered marine species identified by the IUCN Red List are found within these protected zones – underscoring how critical their placement is. However, coverage remains far below what is needed: the UN reports that only 8.4 percent of the ocean is currently designated as MPAs, well below the 30 percent target agreed for 2030 under the Kunming-Montreal Global Biodiversity Framework. A significant challenge is MPA quality. Research in npj Ocean Sustainability highlights that many existing MPAs are under-enforced “paper parks” without meaningful ecological benefits – meaning that expanding area coverage alone is insufficient without adequate management, monitoring, and enforcement.

Sustainable fishing practices 🔗

Science-based fisheries management is essential for reversing stock depletion. This includes setting catch limits tied to maximum sustainable yield (MSY), enforcing seasonal fishing bans during spawning periods, eliminating harmful subsidies that incentivise overcapacity, and transitioning to selective fishing gear that reduces bycatch. Community-based management approaches have also shown promise – traditional resource management systems such as the Indonesian sasi system, which regulates when and how species can be harvested, have successfully restored local fish stocks while maintaining cultural practices. At the industrial scale, FAO’s Blue Transformation Roadmap calls for urgently scaling sustainable fisheries practices globally, warning that failure to act will continue to erode both biological sustainability and food security.

Pollution control 🔗

Reducing marine pollution requires action at the source. Strengthening controls on agricultural runoff, improving wastewater treatment in coastal areas, banning or phasing out single-use plastics, and enforcing discharge regulations for shipping are all necessary measures. At a systemic level, the UN’s SDG 14 calls on countries to prevent and significantly reduce marine pollution of all kinds by 2025, with particular focus on land-based sources. Integrated coastal zone management (ICZM) – which brings together land-use planning, watershed management, and marine governance into a single framework – is increasingly recognised as the most effective way to address the land-to-sea pollution pathway comprehensively.

Global frameworks for marine conservation 🔗

No single country can manage the ocean alone. Because fish migrate across borders, pollution travels freely through ocean currents, and climate change affects every coast, effective marine governance requires coordinated international action.

UNCLOS: the constitution for the oceans 🔗

The United Nations Convention on the Law of the Sea (UNCLOS), adopted in 1982 and entering into force in 1994, is the foundational legal framework governing all marine and maritime activities. As of 2024, 169 sovereign states and the European Union are parties to the treaty. UNCLOS established Exclusive Economic Zones (EEZs) extending 200 nautical miles from a coastal state’s baseline, granting those states sovereign rights to explore, exploit, conserve, and manage all living and non-living resources within that zone. It also obligates all states to cooperate in the conservation of living marine resources on the high seas and to protect the marine environment – though its provisions on high seas fisheries management were recognised as too vague to be actionable, which led to the development of supplementary agreements.

The UN Fish Stocks Agreement and regional fisheries bodies 🔗

The 1995 United Nations Fish Stocks Agreement (UNFSA) was developed to fill the practical governance gaps left by UNCLOS, particularly for straddling stocks and highly migratory species like tuna that move across EEZ boundaries and through the high seas. The UNFSA delegates day-to-day management responsibility to Regional Fisheries Management Organizations (RFMOs), which govern specific ocean regions and fish species through binding conservation and management measures. Almost all high-seas areas outside polar regions are covered by a tuna RFMO. In 2023, negotiations concluded on the Biodiversity Beyond National Jurisdiction (BBNJ) Agreement – also known as the High Seas Treaty – which entered into force in January 2026. This agreement addresses marine protected areas, environmental impact assessments, and the fair sharing of marine genetic resources in areas beyond national jurisdiction, closing a critical governance gap that UNCLOS alone could not cover.

SDG 14 and international commitments 🔗

UN Sustainable Development Goal 14 – “Life Below Water” – consolidates global commitments around marine conservation into measurable targets: ending overfishing, eliminating harmful fisheries subsidies, reducing marine pollution, protecting at least 30 percent of oceans by 2030, and increasing the economic benefits from sustainable marine use for small island developing states and least developed countries. Progress against these targets, however, remains deeply inadequate. The UN’s own assessment notes that only 8.4 percent of the ocean is currently designated as MPAs, and just 46 percent of marine key biodiversity areas are formally protected. Meanwhile, the SDG indicators confirm that fish stock sustainability has worsened, not improved, since the targets were set. Accelerating implementation – through greater investment, stronger enforcement, and deeper international cooperation – is essential if the targets are to be achieved at all.

The path forward 🔗

Marine resource management sits at the intersection of ecology, economics, food security, and geopolitics. The data is unambiguous: oceans are degrading faster than current governance structures are responding. Yet the tools to reverse this – scientifically managed fisheries, effective MPAs, pollution reduction, and binding international frameworks – are well understood and, in many cases, already available. What is needed is political will, adequate financing, and genuine cross-border collaboration to translate commitments on paper into measurable improvements in ocean health. The communities most dependent on marine resources – small-scale fishers, coastal populations, and island nations – also need a meaningful seat at the table in decisions that determine the future of the ocean they live alongside.

What do you think? Given that nearly 38 percent of global fish stocks are being harvested at unsustainable levels, do you think the voluntary nature of most international fisheries agreements is sufficient – or does effective ocean governance require stronger, legally binding mechanisms with real enforcement teeth? And with only 8.4 percent of the ocean currently protected against the 30 percent target for 2030, what should governments prioritise: expanding the coverage of MPAs, or improving the quality of enforcement within the areas already designated?

References

1. https://www.un.org/sustainabledevelopment/oceans/
2. https://openknowledge.fao.org/server/api/core/bitstreams/66538eba-9c85-4504-8438-c1cf0a0a3903/content/sofia/2024/status-of-fishery-resources.html
3. https://openknowledge.fao.org/server/api/core/bitstreams/e65621f8-6379-4c6c-9f4a-d683a9c01ac9/content
4. https://unstats.un.org/sdgs/report/2022/goal-14/
5. https://oceansconnectes.org/en/rapport-2024-unesco/
6. https://pmc.ncbi.nlm.nih.gov/articles/PMC8900478/
7. https://www.nature.com/articles/s44183-025-00169-8
8. https://www.fao.org/publications/fao-flagship-publications/the-state-of-world-fisheries-and-aquaculture/en
9. https://sdgs.un.org/goals/goal14
10. https://en.wikipedia.org/wiki/United_Nations_Convention_on_the_Law_of_the_Sea
11. https://en.wikipedia.org/wiki/High_seas_fisheries_management