Sustainable Fishery Economics: Balancing Profits and Ecosystems

Fisheries feed billions of people, support coastal livelihoods, and generate hundreds of billions of dollars in global trade annually. Yet the economics of how we fish – who can fish, how much they take, and under what rules – directly determines whether these resources thrive or collapse. FAO’s 2025 review of the world’s marine fisheries found that 35.5% of all assessed fish stocks are currently overfished. Behind that number is a set of economic dynamics that, once understood, make the path toward sustainable fisheries much clearer.

Fishery as a renewable resource 🔗

Fish populations are renewable resources – meaning they can regenerate if given the chance. Unlike coal or oil, a well-managed fish stock can produce yields indefinitely because populations grow, reproduce, and replenish themselves. But this renewable status has a critical condition: the rate of harvest must not exceed the rate of biological growth.

Fisheries economists model this using the concept of bioeconomic equilibrium – the point at which the biological growth of a fish stock and the economic forces driving fishing effort reach a stable balance. The most widely used framework for this is the Gordon-Schaefer model, developed in the 1950s, which links fish population dynamics with the cost and revenue structure of fishing operations. In this model, fish biomass follows a logistic growth curve: populations grow fastest at intermediate sizes and slow down as they approach their carrying capacity. Three key management reference points emerge from this model:

• Maximum Sustainable Yield (MSY) – the largest average catch that can be taken from a stock over the long term without reducing its productivity.
• Maximum Economic Yield (MEY) – the catch level that maximizes net profit, typically achieved at a lower fishing effort than MSY.
• Bioeconomic Equilibrium (BE) – the point under open-access conditions where total revenue equals total cost and economic profit drops to zero.

Understanding where a fishery sits relative to these reference points is the foundation of both fisheries science and fisheries policy.

Open access vs. private property fishery models 🔗

The ownership structure of a fishery – who has the right to fish and under what conditions – has an enormous impact on how fish stocks are managed and whether they survive long-term.

The open access problem 🔗

In an open-access fishery, anyone can fish without restriction. This sounds equitable, but it produces a well-documented economic trap. As fishing becomes profitable, more boats enter the fishery. Each new entrant competes for the same stock, driving down individual catches and pushing the system toward the bioeconomic equilibrium – the point where profits are completely eroded. In an open-access situation, fishers continue entering the fishery until revenue equals cost and net profit falls to zero, which typically results in far more fishing effort than is biologically sustainable. This is the classic “tragedy of the commons” applied to fisheries.

The Gordon-Schaefer model predicts that under open access, the fishing effort at bioeconomic equilibrium is approximately double the effort required to achieve maximum economic yield. This means open-access fisheries are systematically biased toward overexploitation. A shift from open-access to private property fisheries can lead to more societally optimal fishing effort, better protecting both marine species and ocean health.

The private property advantage 🔗

Under a private property or rights-based model, access to the fishery is controlled. A single owner – whether an individual, cooperative, or government entity – internalizes both the costs and benefits of fishing decisions. Because they bear the consequences of overexploitation directly, they have an incentive to manage stocks conservatively. Secure fishing rights programs, also called catch shares, allocate a defined share of the total allowable catch to specific participants. This eliminates the competitive race to fish and gives operators the flexibility to fish when conditions are optimal rather than racing others to the water.

Under MSY, the fish population is maintained at the level of maximum biological productivity – roughly half the carrying capacity. At this intermediate population density, individuals breed at their maximum rate, generating the greatest surplus production available for harvest. A private property fishery, properly regulated, can hold effort near MEY – lower than MSY – which achieves both conservation and profitability goals simultaneously. Maximum economic yield is generally reached at a lower fishing mortality than MSY, meaning it keeps the fishery in a healthier biological condition while still generating strong economic returns.

Calculating catchability and effort 🔗

The relationship between fishing effort and actual fish caught is not straightforward. It depends heavily on a parameter called the catchability coefficient (q). In the Gordon-Schaefer model, the harvest function is expressed as:

H(t) = q × S(t) × E(t)

Where H is the harvest, S is the stock size, and E is fishing effort. The catchability coefficient q represents the fraction of the fish population that a single unit of effort will catch. A higher q means more fish are caught per unit of effort for any given stock level – reflecting more efficient gear, better technology, or favorable ocean conditions.

This has direct implications for sustainable management. Technical change modeled as an increase in the catchability coefficient means the same catch can be achieved with less effort – but it also means that under open-access conditions, fish stocks will be driven down to a lower equilibrium level even as profits remain zero. Improved efficiency does not automatically benefit the fishery; it can simply intensify depletion.

Real-world catchability data illustrates this clearly. A bioeconomic study of Hilsa fisheries in West Bengal and Bangladesh found that the catchability coefficient in West Bengal was roughly 20 times higher than in Bangladesh. As a result, increasing effort in West Bengal actually decreased yields, while the same increase in Bangladesh raised yields – demonstrating how profoundly catchability shapes the required effort to fish sustainably and the design of appropriate management responses.

Managers must therefore account for catchability when setting total allowable catches or effort limits. As gear improves or fleets modernize, the effort ceiling for sustainable fishing must be recalibrated downward – otherwise the fishery will be pushed past its biological limits even as individual operators feel they are working “normally.”

Moving towards sustainable fisheries 🔗

The economics of fisheries make clear that sustainability does not happen by accident. It requires active governance that corrects the incentive failures of open access and aligns economic reward with ecological stewardship. Several policy approaches have proven effective:

Individual transferable quotas (ITQs) 🔗

Individual Transferable Quotas (ITQs) assign each licensed fisher a specific share of the total allowable catch, and these shares can be bought, sold, or leased. This creates a property-rights structure within a managed fishery. ITQs provide greater incentives for sustaining and optimizing economic performance and have been successfully implemented in Australia, New Zealand, Iceland, and elsewhere. When quota holders know their future catch depends on current stock health, they develop a long-term interest in conservation. ITQ systems grant fishers exclusive and transferable rights to catch a set percentage of the MSY, eliminating the race-to-fish dynamic that drives overexploitation.

Marine protected areas (MPAs) 🔗

Marine Protected Areas (MPAs) restrict or prohibit fishing in designated zones, allowing fish populations to rebuild in refugia that then seed surrounding areas. MPAs can restore fish stocks by destabilizing the catastrophic equilibrium of overexploitation and shifting the system toward a stable, sustainable fishery equilibrium – particularly where stock depletion has pushed populations toward collapse.

Science-based total allowable catches 🔗

Setting Total Allowable Catches (TACs) based on rigorous stock assessments is the backbone of modern fisheries management. The goal is to keep harvest within the biological surplus – the amount a population produces above what it needs to maintain itself. FAO’s 2025 data shows that in the Northeast Pacific, where science-based management is well-established, 92.7% of stocks are sustainably fished – far above the global average. This demonstrates what effective governance can achieve.

Territorial use rights in fisheries (TURFs) 🔗

TURFs allocate exclusive rights to fish in a specific geographic area to a community or group. This approach is particularly well-suited to small-scale and artisanal fisheries where thousands of fishers operate across dispersed coastal zones. TURF participants are required to comply with controls on fishing mortality and maintain healthy ecosystems – creating community-level accountability rather than top-down enforcement.

Combating illegal, unreported, and unregulated (IUU) fishing 🔗

No management system works if its limits are routinely circumvented. An estimated one in five fish are caught illegally, with illegal, unreported, and unregulated fishing accounting for 30% of all fish sourced from developing countries’ fisheries. Strengthening monitoring, surveillance, and international cooperation – particularly through the 17 Regional Fisheries Management Organizations (RFMOs) – is essential for closing the governance gaps that allow overexploitation to continue unchecked.

The economics of getting it right 🔗

Fisheries economics makes a compelling case: unsustainable fishing is not just an ecological failure, it is an economic one. A joint study by FAO and the World Bank found that the gap between the potential and actual net economic benefits from marine fisheries amounts to approximately $50 billion per year – a direct consequence of overexploitation, overcapacity, and poor governance. That is not just lost fish; it is lost food security, lost livelihoods, and a lost opportunity to sustainably manage one of the planet’s most productive renewable resources.

The good news is that the tools exist. Bioeconomic models give us the analytical foundation to set scientifically grounded limits. Rights-based management corrects the incentive failures of open access. And where these approaches are applied consistently, fish stocks recover. The challenge is political will, institutional capacity, and the determination to manage for the long term rather than the next season.

What do you think? If a government must choose between maximizing short-term fish harvests for food security and restricting catches to allow stock recovery, how should that trade-off be weighed? And given that open-access fisheries systematically push toward zero-profit equilibrium, why do so many fishing nations still resist moving toward rights-based management?

References

1. https://www.fao.org/newsroom/detail/fao-releases-the-most-detailed-global-assessment-of-marine-fish-stocks-to-date/en
2. https://www.fao.org/4/w6914e/w6914e02.htm
3. https://www.sciencedirect.com/topics/earth-and-planetary-sciences/fishery-economics
4. https://link.springer.com/chapter/10.1007/978-3-031-20754-9_6
5. https://fisherysolutionscenter.edf.org/build-knowledge/sustainable-fisheries
6. https://en.wikipedia.org/wiki/Maximum_sustainable_yield
7. https://medcraveonline.com/JAMB/maximum-sustainable-yield-maximum-economic-yield-and-sustainability-in-fisheries.html
8. https://rlhick.people.wm.edu/posts/gordon-shaefer-model.html
9. https://www.sciencedirect.com/science/article/abs/pii/S0308597X19307043
10. https://www.fao.org/4/X6947E/x6947e09.htm
11. https://earth.org/the-future-of-sustainable-fishing-more-oversight-and-lower-yields/
12. https://www.researchgate.net/publication/373103517_Maximum_Sustainable_Yield_for_a_fishery_with_variable_price
13. https://www.un.org/depts/los/convention_agreements/reviewconf/FishStocks_EN_A.pdf