How Can Overfishing Be Prevented? Key Solutions

Overfishing can be prevented, but no single policy does the job alone. The most effective approaches combine science-based catch limits, spatial protections like marine reserves, economic reforms that remove perverse incentives, and enforcement technologies that make cheating harder. Some of these tools already have strong track records; others remain frustratingly underused. The gap between knowing what works and actually implementing it is where most fish stocks continue to suffer.

Setting Catch Limits That Reflect the Science

The most fundamental tool against overfishing is also the most intuitive: don’t take more fish than a population can replace. Fisheries scientists calculate what is known as the maximum sustainable yield for a given stock, the largest amount you can harvest year after year without driving the population down. The problem is that many fisheries around the world either lack these calculations or ignore them. A 2024 modeling study estimated that if all overfished stocks worldwide were brought up to their sustainable-yield levels, the long-run catch from those stocks could increase by roughly 40%, translating to an additional catch of about 10.6 million metric tons of seafood per year on top of current marine harvests.¹ That is a striking number: overfishing doesn’t just threaten ecosystems, it actively shrinks the food supply.

Getting to those sustainable-yield targets requires political will. Quota-setting bodies often face pressure from fishing industries and national governments to allow higher catches than scientists recommend. This is a recurring theme across almost every fishery management challenge discussed below: the science is usually ahead of the politics.

Marine Protected Areas and the Spillover Effect

Marine protected areas, or MPAs, work by closing off portions of the ocean to fishing. Inside the boundaries, fish populations grow larger and more abundant. The conservation case is straightforward, but the question fishers and policymakers always ask is whether those protected fish ever benefit the people who fish outside the boundaries. Increasingly, the evidence says yes.

A study examining nine large-scale MPAs across the Pacific and Indian Oceans found that catch rates in tuna purse seine fisheries increased by about 12 to 18% near MPA boundaries, with the effect fading at greater distances.² Bigeye tuna showed a stronger spillover effect than skipjack tuna, consistent with what fisheries models would predict for species with different movement patterns. A separate study of the world’s largest fully protected MPA confirmed spillover benefits specifically for yellowfin and bigeye tuna.³

A broader meta-analysis found that fish biomass and abundance outside fully protected areas was consistently higher close to the boundaries (within about 200 meters) compared to farther away. The spillover effect was slightly stronger when MPAs were larger, older, and surrounded by partially protected buffer zones.⁴ Commercially valuable species showed especially strong spillover, which matters because those are precisely the species under the most fishing pressure. The takeaway for fisheries management is that MPAs are not just conservation tools. When well designed and well placed, they function as fish banks that pay dividends to nearby fishing fleets.

Giving Fishers a Stake in the Resource

One of the oldest problems in fisheries is the “race to fish.” When many boats compete for a shared quota, every captain has an incentive to catch as much as possible before the quota runs out, leading to dangerous working conditions, wasted bycatch, and economic inefficiency. Rights-based management systems try to break this dynamic by giving individual fishers or communities a defined share of the total allowable catch.

Individual transferable quotas, or ITQs, assign each vessel or firm a portion of the total catch that they can harvest at their own pace, and in many systems, trade with other fishers. With adequate enforcement, ITQs have been shown to curb the race to fish and improve both sustainability and profitability.⁵ Denmark’s experience with ITQs demonstrated that quotas reduced overcapacity and even cut fuel consumption because fishers no longer needed to rush.⁶

A related approach works at the community level. Territorial use rights for fisheries, known as TURFs, grant exclusive fishing rights over a defined area to a local group or community. Evidence from countries including Japan, Vietnam, and Chile shows that TURFs can conserve stocks, improve yields, and give fishers more bargaining power over prices.⁷ Because the community knows it will be the one fishing that area next year and the year after, the incentive shifts from short-term extraction to long-term stewardship. Fish movement complicates things, though. When target species migrate across TURF boundaries, cooperation between neighboring communities becomes essential for the system to work.⁸

Reforming Fisheries Subsidies

Governments worldwide spend enormous sums subsidizing their fishing fleets, and much of that money makes overfishing worse. A comprehensive analysis estimated global fisheries subsidies at roughly $35.4 billion in 2018, of which about $22.2 billion were “capacity-enhancing” subsidies, the kind that artificially boost fishing power through fuel discounts, boat-building grants, and similar payments.⁹ Fossil fuel subsidies made up a growing share of this harmful total. Without these payments, many fishing operations that deplete stocks would simply not be profitable enough to continue.

The World Trade Organization reached an agreement in principle to discipline harmful subsidies, but turning that agreement into real reform is proving slow. A study of China’s subsidy reduction offers useful lessons about the complexities. Reducing harmful subsidies did accelerate the retirement of fishing vessels, but only when paired with retirement subsidies that compensated fishers for leaving. In other words, simply yanking subsidies away may not shrink a fleet if fishers have no viable exit.¹⁰ The broader lesson is that subsidy reform works best as part of a package, not as a standalone policy.

Smarter Fishing Gear

A huge share of global bycatch, the unintended capture of non-target species, comes down to gear design. Trawl nets, in particular, can sweep up everything in their path. Simple modifications to gear can make dramatic differences. In Australia’s northern prawn trawl fishery, nets fitted with turtle excluder devices reduced sea turtle catches by 99% and cut catches of larger sharks and rays by 86% and 94%, respectively.¹¹ The commercial prawn catch fell by only about 6%, and the quality of the catch actually improved because the gear excluded large debris that would otherwise damage it.

Similar results have emerged in the Mediterranean, where a flexible turtle excluder device tested in bottom trawls had no measurable effect on the weight or composition of the commercial catch while significantly reducing debris and litter.¹² These findings matter because one of the biggest barriers to gear reform is fisher resistance. If modified gear doesn’t cost them income, adoption becomes far easier to mandate and enforce.

Ghost fishing by abandoned, lost, or discarded gear is another dimension of the problem. Nets and traps that are lost at sea continue catching and killing marine life indefinitely. Retrieval programs and biodegradable gear designs can reduce the duration that ghost gear remains dangerous in the ocean.¹³ Mandatory gear marking, which allows lost equipment to be traced back to its owner, provides an added incentive to avoid gear loss in the first place.

Technology for Monitoring and Enforcement

Rules about where, when, and how much you can fish only matter if someone is watching. Historically, monitoring relied on human observers aboard fishing vessels, an expensive and logistically difficult approach that could only cover a fraction of trips. Two technological shifts are changing this picture.

First, satellite-based vessel tracking, through systems like the Automatic Identification System (AIS) and Vessel Monitoring Systems (VMS), allows authorities to see where fishing boats go. AI algorithms can now analyze these tracking signals to distinguish actual fishing activity from transit, making it possible to estimate fishing effort across entire ocean basins.¹⁴ The catch is that some vessels turn off their transponders when they want to fish illegally, so satellite tracking works best when paired with radar-based detection of “dark” vessels.

Second, electronic monitoring with onboard cameras is beginning to supplement and in some cases replace human observers. A comparative study found that camera systems recorded between about 64% and 99% of captured species depending on the type of fishery, with trammel net operations reaching near-complete coverage.¹⁵ Camera accuracy was lower in chaotic purse seine operations, which suggests the technology still needs improvement for certain fleet types. But the trajectory is clear: electronic monitoring is becoming cheaper and more reliable, making full-fleet coverage a realistic goal for the first time.

Stopping Illegal Fishing at the Port

Even the best ocean patrols can miss illegal vessels. A complementary strategy is to catch them when they come to shore. The Port State Measures Agreement, an international treaty, requires participating countries to inspect foreign fishing vessels that seek to use their ports and to deny access to vessels suspected of illegal, unreported, and unregulated (IUU) fishing.¹⁶ The logic is elegant: every fishing vessel eventually needs a port, and port inspections are far cheaper than at-sea patrols. Standardized inspection protocols and information sharing between countries are critical to making the system work, because illegal operators will simply divert to less vigilant ports if enforcement is uneven.

Ecosystem-Based Management

Traditional fisheries management focuses on one species at a time: set a quota for cod, a separate quota for herring, and so on. Ecosystem-based fisheries management takes a wider view, considering how harvesting one species affects predators, prey, and the broader food web. European law now formally requires this approach in EU waters. Modeling of the western Baltic Sea found that an ecosystem-based strategy would allow recovery of harbor porpoises, forage fish, and cod stocks while simultaneously increasing catches of herring and cod.¹⁷ That study also noted a bonus: recovering fish stocks store more carbon in their biomass, so ecosystem-based management has climate co-benefits.

The concept extends beyond just food-web interactions. Incorporating indigenous and local knowledge into management decisions can fill gaps that conventional science misses. Research on Dungeness crab in Pacific Canada found that indigenous knowledge provided locally relevant data that improved fisheries management and conservation outcomes.¹⁸ Fishers and coastal communities who have observed marine systems for generations often hold detailed understanding of seasonal patterns, spawning behavior, and habitat changes that scientific surveys may overlook.

When Solutions Fall Short

Not every tool works as advertised. Seasonal closures, where fishing is banned during spawning periods, are among the most politically palatable management measures because they feel fair and temporary. But an evaluation of a spawning-area closure in the Firth of Clyde found no measurable effect on fish abundance or spawning-stock biomass; the decline continued at the same rate inside and outside the closed area.¹⁹ Closures can work if they cover enough of a stock’s critical habitat during the right time window, but poorly designed closures give the appearance of action without delivering results.

Vessel buyback programs, where governments pay fishers to retire boats and reduce fleet capacity, have a similarly mixed track record. One industry-funded buyback in the U.S. generated economic returns that substantially exceeded its financing costs, suggesting it paid for itself.²⁰ But a broader survey of buyback programs worldwide concluded that they are generally not effective at achieving their objectives, often because the remaining fleet expands its effort to fill the gap left by retired vessels.²¹ Without strict limits on how the remaining fleet operates, removing boats is just a temporary fix.

Ecolabeling programs like the Marine Stewardship Council (MSC) aim to harness consumer demand for sustainably caught fish. The MSC has driven some real process improvements in certified fisheries, and the concept of using market pressure to reward good practices is sound.²² But researchers have cautioned that certification alone is unlikely to solve overfishing or rebuild depleted stocks. Government-led measures like marine reserves, access restrictions, and enforcement against illegal fishing remain necessary. Ecolabels work best as one layer in a broader management system, not as a substitute for regulation.

The High Seas Governance Gap

About two-thirds of the ocean lies beyond any nation’s jurisdiction, and these high seas are governed by regional fisheries management organizations, or RFMOs. An expanded evaluation of all 16 major RFMOs scored them on management performance using 100 questions across ten categories. The average score was a dismal 46 out of 100. More troubling, the study found no meaningful relationship between an RFMO’s management score and the actual health of the fish stocks in its waters. On average, about 56% of stocks targeted within RFMO convention areas were considered collapsed or overexploited, and that proportion increased between 1996 and 2018.²³ Stakeholder involvement and voting rights scored lowest, averaging just 2.3 out of 10, which hints at why these bodies struggle: the people most affected by their decisions have the least voice.

The evidence here is sobering. Even when RFMOs adopt the right policies on paper, implementation gaps, non-compliance by member states, and the sheer difficulty of enforcing rules in remote waters undermine results. Strengthening high-seas governance is arguably the single hardest piece of the overfishing puzzle, and one where progress has been slowest.

Climate Change Is Rewriting the Map

Warming oceans are pushing fish populations toward the poles. This is more than an ecological curiosity; it is a governance nightmare. Many commercially important species straddle the boundaries between national waters and the high seas, and their shifting ranges can move them across jurisdictional lines that were drawn decades ago under very different conditions.²⁴

The productive Northeast Atlantic offers a case study in how badly this can go wrong. Quota agreements for widely distributed species like mackerel and Norwegian spring-spawning herring were originally negotiated when stocks were distributed farther south. As fish moved northward, new nations claimed access, old agreements collapsed, and several stocks now have no overall management consensus.²⁵ Meanwhile, Northern hake expanded north beyond EU waters into the North Sea, but quotas were still being set unilaterally by the EU as of the study period, ignoring the new reality. Climate-driven distribution shifts demand flexible, adaptive agreements that can update allocations as stocks move, and most current governance structures are not built for that kind of agility.

Aquaculture, Cell-Based Seafood, and the Demand Side

Some advocates argue that reducing demand for wild-caught fish is the other half of the equation. Aquaculture now supplies a large share of global seafood, but it is not entirely independent of wild fisheries. Fed aquaculture depends heavily on fishmeal and fish oil derived from wild forage fish. Modeling suggests that if forage fish catches decline by 5 to 19% due to management reforms and climate impacts, fed aquaculture production could drop by 8 to 35%, particularly in countries farming carnivorous species.²⁶ Developing alternative feed ingredients is a pressing priority.

Cell-based seafood, grown from fish cells in a lab rather than caught or farmed, has attracted attention as a potential way to ease fishing pressure. Proponents point to its potential sustainability and climate resilience benefits.²⁷ But a sober analysis of the pathway from lab to market to ocean recovery concluded that the chain of events needed for cell-based seafood to actually reduce fishing pressure is long and tenuous. Technological hurdles, consumer acceptance, market displacement dynamics, and the disconnect between which species are fished and which are likely to be cultured all work against the optimistic narrative.²⁸ Cell-based seafood may eventually contribute to a broader portfolio of solutions, but it is not a substitute for managing wild fisheries properly right now.